Spina Bifida, Spinal Dysraphism, Myelomeningocele and Meningocele

Spinal dysraphism means a spectrum of congenital anomalies of the spine and spinal cord.

Spina bifida is a common form of spinal dysraphism. The term spina bifida includes a wide variety of anomalies.
  
Congenital defect in the spine leads to spina bifida. This can be of two types: spina bifida occulta and spina bifida aperta.

In spina bifida aperta; visible lesion, like a swelling over the midline of the back may be noticed at the time of birth of a child. Such spinal dysraphism is known as Spinal Bifida Aperta.

But, a child may be having some abnormalty of the spine or spinal cord but without any externally visible lesion and overlying skin is intact, then it is known as Spina Bifida Occulta.  This defect of the vertebrae of the spine of a child may not be visible at the time of birth and there may be no visible exposure of meninges or neural tissue. And, there may be congenital defect only in the lamina of the vertebrae of the spine without any involvement of underlying spinal cord. This is known as spine bifida occulta.

But, in spina bifida aperta there is a visible or open defect in the spine. There may be congenital defect in vertebral arches with cystic distension of meninges which is filled with CSF and is known as Meningocele. If, in this congenital defect of the vertebral arches there is a cystic dilatation of meninges and cerebrospinal fluid along with neural tissue or spinal cord ( Myelon) , then it is known as Myelomeningocele. If Myelomengocele contains fat tissue, then it is known as Lipomyelomengocele.

Myelmeningocele is one of the congenital open neral tube defect present at the birth on the back of the newborn.

It is a common type of congental defect of the spine and its incidence is about 1 in 1,000 live births. Better nutrition and folic acid suplementatiion during the antenatal care of the mother decrease its occurrence.

Ultrasound study during the early antenatal care detects any occurrence of myelomeningocele in a fetus during pregnancy.

A newborn child should be assessed for any sensory or motor deficit due to meningocele or myelomeningocele. There may be associated congenital lesions, like cardiac lesions. Myelomeningocele may be associated with congenital hydrocephalus. So, MRI of the spinal cord and brain is investigation for choice for assessing a case of meningcele. MRI may show whether a swelling on the back of a child is only flled with CSF or does it contain any neural tissue. It detects any intraspinal extension, associated intrasinal dermoid, lipoma, dermal sinus, spina bifida, spinal dysrahism like duplication of the cord, any bony spur between the duplicated cord, Chiari malfomation, syrinx, hydrocephalus, thickened filum terminale, etc. So, MRI helps in diagnosis, surgical planning and predicting prognostic outcome.
.

   

Arachnoid cysts, Ependymal cysts, Benign intracranial developmental cysts

Intracranial Benign Developmental Cysts

Arahnoid cysts and Ependymal cysts

It is very common observation in brain imaging to find small cysts inside the brain. These cystic areas resemble and look like areas of the brain with normal cerebrospinal fluid. Such incidental finding increase anxiety in the person in whom brain imaging was usually  done for some other purpose. Such cysts are usually arachnoid cysts or ependymal cysts.

Arachnoid Cysts

Arachnoid cyst is a benign intracranial developmental cyst which is between two split layers of arachnoid and it usually contains clear colurless CSF.

So, arachnoid cyst is a cyst containing CSF and it forms due to splitting of the archnoid membrane. These are benign congenital malformation.

It is usually an incidental finding.

They are commonly seen in Sylvian fissure, cerebellopontine angle, supracollicular area, vermian area, sellar and suprasellar area, etc. This may appear at any age from infancy and adolescence to adults.

Arachnoid cyst may remain asymptomatic throughout life, only to be diagnosed incidentally by a neuroimaging study. Imaging often shows remodelling of bone, and imaging characteristics exactly mimic CSF on CT and MRI in most cases.

Symptoms and signs of arachnoid cyst depend on its size and location inside the brain and spinal cord.

Recommendation for incidentally discovered arachnoid cyst in adults: a single follow up imaging study in 6-8 months is usually adequate to rule-out any increase in size. Subsequent studies only if concerning symptoms develop.

Sylvian fissure archnoid cyst may present with headache, seizures, dysarthria (speech problem),  focal bulge in temporal region, exophthalmos, papilloedema, and hemiparesis.  X-ray skull or CT scan may show evidence of expansion of the middle cranial fossa, elevation of the lesser wing of the sphenoid, forward protrusion of the greater wing the sphenoid bone and outward expansion and thinning of the temporal bone. But expansion of skull in relation to arachnoid cyst is not an indication for surgery , but mass effect, displacement of midline structures and presence of obsructive hydrocephalus are indications for surgical intervention for middle fossa arachnoid cysts.

On CT, arachnoid cyst appear as low density, smooth bordered lesions having attenuation values similar to that of CSF. The cyst wall has well-defined margins and does not enhance after intravenous injection of contrast agent.

MRI is better at demonstrating multiplanar relationship and characteristics of the lesion on T1, T2, FLAIR, Diffusion weighted images and contrast, MTR ( Magnetization transfer ratio), MRS ( MR spectroscopy), MRA ( MR angiography)study. It helps in differentiating arachnoid cyst from epidermoid, dermoid, lipoma, ependymal cysts, tumors like low grade glioma & metastasis, old hemorrhage, cavernoma, hydatid cyst, hemangioma, and infective granulomas.

On T1 weighted image arachnoid cyst appears hypointense and on T2 weighted image it appears hyperintense like CSF. On T1 weighted MRI ,  lipomas will appear hyperintense as fat appears hyperintense on both T1 and T2 weighted images.

The high protein content of a nonhemorrhagic tumour cyst will cause the cyst to appearslightly hyperintense to CSF on proton density images. The associated peritumoural oedema of cystic astrocytoma will look hyperintense on FLAIR image of MRI.

Ependymal cysts and epidermoid tumors appear isointense or slightly hyperintense to CSF on proton-density images. Epidermoid tumors are more likely to be lobulated, have less distinct margins, and encase rather than displace neighbouring structures. Diffusion-weighted imaging reflects the amount of Brownian motion of proteins which is greater in cystic than in solid lesions.

Sylvian fissure is the most common site for intracranial arachnoid cysts. Sylvian fissure arachnoid cyst may be of three types. It may be a small lenticular lesion at the anterior pole of the middle cranial fossa without any mass effect (Type 1) or quadrangular in shape reflecting a completely open insula (Type II) .  Type III sylvian fissure arachnoid cyst presents as large rounded area with significant compression of the brain. Displacement of the midline structures in type III cysts is an indication for surgical decompression.

Treatment of archnoid cyst

Adults with asymptomatic arachnoid cyst should be treated conservatively, even for large cysts without symptoms and signs or with only a complaint of headache. Only arachchnoid cysts which cause a mass effect or neurological deficit should be treated surgically.

In children, decompression of sylvian fissure archnoid cyst is more likely to lead to decreased parenchymal compression, cyst collapse, and subsequent resolution if intracranial hypertension and neurological deficits.

Ventriculoperitoneal shunting

Cystoperitoneal shunting

Cyst fenestration

Cyst excision

Skull may be very thin and may be even eggshell-like, so care must be taken in placing burrhole during surgery. The dura is bluish because of presence a large pool of fluid underneath. The exposed cyst wall may be clear and transparent; in some  areas  a web of milky thickening may be noted as a result of collagen reinforcement. The forntal lobe appears widely separated from the temporal lobe because of the failure of opercula to develop. So, the insula and branches of middle cerebral artery may be completely exposed after excision of the sylvian fissure arachnoid cyst. When the outer wall of the cyst is excised, clear CSF escapes. Long bridging veins may be observed either on the surface of the cyst or within the cyst. Bridging veins that traverse the cavity of the cyst do not have much support. Rupture of such unsupported veins account for high incidence of subdural hematoma associated with these cysts.

Fenestration of deep wall of cyst creates a communication between the sylvian fissure cyst and the chiasmatic cistern.

A significant number of middle cranial fossa arachnoid cysts are associated with bleeding hematomas which are usually venous in nature and result from tearing of bridging veins within or external to the cyst.  It may precipitate symptoms in a previously asymptomatic patient.

Arachnoid cyst in sella turcica

Sella turcica arachnoid cyst may be intrasellar or suprasellar. Suprasellar cysts are by far the more common. It may present with hydrocephalus, visual impairment, endocrine dysfunction ( hypopituitarism, stunted growth, etc), gait disturbance. A curious head nodding motion described as the “ bobble-head doll syndrome” has been described in suprasellar arachnoid cyst. The nodding or bobbing consists of irregular involuntary head motions in the anteroposterior direction occurring two to three times per second.The motion is reminiscent of that seen in dolls with a weighted head resting on a coiled spring; hence the name of this syndrome. Some degree of mental retardation is associated with this syndrome.

Treatment of suprasellar sella turcica arachnoid cysts are ;endoscopic ventriculostomy with concomitant fenestration of lamina terminalis, subfrontal cyst excision with communication to the basal cisterns, and transcallosal or transventricular cyst excision with concomitant cystoperitoneal shunting.

Treatment of intrasellar sella turcica arachnoid cysts is trans-sphenoidal approach with packing of sella with fat or fascia or muscle tissue.

Arachnoid cysts in Interhemispheric Fissure

Two types of arachnoid cysts occur near the midline in the supratentorial space.

1.       Interhemisheric cysts with associated partial or complete corpus callosal agenesis.It straddles the falx and extends equally on either side, compressing the medial surface of both hemispheres. A coronal MRI shows a “ bat-wing” appearance of the lateral horns and dorsal displacement of the third ventricle.

2.       Parasagittal cysts are usually not associated with agenesis of the corpus callosum. The cyst is strictly unilateral and is sharply limited by falx in the midline, thus it tends to be wedge shaped. There is a marked bulging of the frontal and parietal bones in the parasagittal area. The superior sagittal sinus and falx cerebri are considerably off the midline.

Cerebral convexity arachnoid cyst

In infants, it may present with progressive asymmetrical enlargement of head. MRI findings may mimic subdural hygroma, but without an enhancing membrane

In adults, the lesion may present with seizures, headache , papilloedemaand progressive contralateral hemiparesis.  Skull films  may show erosion of the inner table of the skull. CT scan shows biconvex or semicircular area of lucency over the convexity without an enhancing membrane. Surgical therapy consists of excision of the outer membrane of the cyst.

Quadrigeminal cistern arachnoid cysts

These cysts behave like pineal masses and present with hydrocephalus and Parinaud’s syndrome. Therapy consists of excision of the cyst wallthrough an occipital transtenorial approach, with or without insertion of cystoperitoneal shunt.  

Cerebellopontne angle arachnoid cysts

Clinical presentation of arachnoid cyst in CP angle may mimic that of an acoustic neuroma.

Posterior fossa arachnoid cysts

Posterior fossa arachnoid cysts may present in the midline near the fourth ventricle or the cistrna magna, or paramedian area opposite the cerebellar hemisphere. X-ray skull may show a focal expansion of the occipital bone. Diffrential diagnosis of midline posterior fossa arachnoid cyst include mega cistern magna, Dandy-Walker malformation, epidermoid cyst, cystic glioma and hemangioblastoma.

Clival region arachnoid cysts

The clival region is uncommon site for intracranial arachnoid cyst. Although termed clival , the cyst may extend into the interpeduncular cistern or the cerebellopontine angle. The cyst displaces the midbrain and pons dorsally along with basilar artery.The cranial nerves are stretched , elongated , and draped around the cyst.

Other rare locations of arachnoid cysts are  intraventricular, diploic space, etc.

                                         Diagrammatic representation of 3 types of Sylvian fissure arachnoid cyts

Diagrammatic representation of probable mechanism of formation of ependymal cyst 

Two types of interhemisheric arachnoid cysts

   

Ependymal cysts

Ependymal cysts may mimic arachnoid cyst clinically and on imaging studies. They occur much less frequently than arachnoid cysts. They occur in central white matter of the frontal and temoporopatrietal lobes, causing progressive neurological deficits, seizures and features of raised intracranial pressure. The protein content of the cyst fluid is generally greater than that of the CSF; on MRI the cyst will typically appear isointense or slightly hyperintense to CSF on proton density images. The wall is lined by columnar or cuboidal cells with or without cilia. Blepharoplasts may or may not be identifiable , These cysts never communicate with the ventricular system. They are believed to arise by the sequestration of a small segment of the primitive ependymal lining into either the cortical mantle or the perimedullary mesh . treatment consists of drainage of the cyst and excision of its wall.

Sources

Neurosurgery, second edition, volume III Editors: Robert H.Wilkins and Setti S.Rengachary, McGraw –Hill, Chapter 374; Intracranial arachnoid and ependymal cysts by Setti S. Rengachary and Jerome D.Kennedy, pages 3709-3728

Wikipedia

Handbook of neurosurgery , Mark S Greenberg, 7^th edition, Thieme

Tuberculosis of Brain and Spine

I have published a book on Tuberculosis of Brain and Spine. This book is intended to apprise the readers about the strategy to diagnose and promptly treat tubercular infections of the brain, spinal cord and vertebral bodies of the spine. I have made an attempt to propose a method to effectively treat this disease in order to avoid morbidity and mortality associated with TB of central nervous system. Many patients of intracranial and spinal TB can be diagnosed and treated without any surgical intervention. I have incorporated sonme cases who were referred to me for neurosurgery, but they were cured completely without any surgery. So, this book is especially useful for the Physicians, Pediatricians, Orthopedicians , Neurologists and Neurosurgeons.

I need feedback of the readers and others who are involved in treating patients of Extrapulmonary Tuberculosis, So that I can further improvise my clinical approach for the better clinical management. 

Colloid Cyst

Colloid cysts are slow growing benign intraventricular tumor of anterior third ventricle. These constitute less than 1% of all intracranial tumors. It constitutes 14% of intraventricular tumors. It is commonest third ventricular tumor.
It is presumed that it originates from roof of third ventricle from rudimentary paraphysis ( evagination in roof of 3rd ventricle during development). It comprises of fibrous epithelial lined cyst filled with either mucoid or gelatinous or dense hyloid substance.
It is commonly seen in between age groups 20 and 40 years. Colloid cyst is usually located in the anterior third ventricle, at the level of foramen of Monro. It may block the cerebrospinal fluid ( CSF) flow causing symmetrical dilatation of both lateral ventricles and obstructive hydrocephalus. It may present insidiously or suddenly. Headache is a common presentation. Intermittent and postural nature of attacks are other common type of presentation. Drop attack due to sudden weakness of lower limbs with headache is also commonly seen in patients with colloid cyst.
Other common symptoms of colloid cyst are diplopia, gait disturbance, vomoting, disturbed mentattion, blurred vision, incontinence, and vertigo or dizziness.
Occurrence of intermittent symptoms is chracteristic of colloid cyst.
CT scan or MRI with contrast is able to detect a rounded lesion in the anterior third ventricle. Most clinicall significant cysts are more than 1.5 centimeter is size. It may show minimal enhancement or no enhancement on CT or MRI. So, the enlargement of both lateral ventricles and sparing of third and fourt ventricle along with a small globular intraventricular lesion at the level of Foramen of Monor should establish the diagnosis of colloid cyst.
Image 1: CT scan of the brain showing axial view of brain with a hyperdense lesion in the anterior third ventricle with enlargemtnt of both lateral ventricles.

                                                       Image 1 source: radiopaedia.org

Neurosurgery is the definitive treatment. Lumbar Puncture ( LP) is contraindiacted due to risk of herniation. It should be treated surgically as there is risk of acute hydrocephalus and sudden neurological deterioration. Open transcranial surgery or endoscopic neurosurgery are the treatment options. Transcranial surgery may be transcallosal  or transcortical. Endoscopic neurosurgical excisison is the mainstay of treatment.
Trancortical approach involves reaching the third ventricle through right sided middle frontal gyrus. It is feasible when ventricles are enlarged.
Transcallosal approach involves approach to the 3rd ventricle either via the foramen of Monro or by interfornicial approach. This approach can be used even if ventricles are not enlarged. There is risk of venous infarction or fornicial injury in this approach.Injury to the fornisx is associated with memory deficits or behaviour abnormalities.

Reference
1. Handbook of Neurosurgery by Mark S Greenberg 7th Deition, Thieme publication
2. https://en.wikipedia.org/wiki/Colloid_cyst
3.radiopaedia.org

Prescription Audit

Clinical audit is a quality improvement cycle that involves measurement of the effectiveness of care
against agreed and proven standards. The audit cycle includes the assessment of clinical management according to the standards of quality care and interventions then to re-measure the outcome to
make further improvements.
Aim of the audit is to identify & rectify the deficits and then improve. Monitoring , Assessment, Feedback, Discussion, Reassessment are important steps to make any improvement in medical management in healthcare organization.
The mistakes are bound to occur in situations where doctors are treating, reviewing the history, examining the patient as well as documenting the patient care. So, aim should be to improvise the process and not just the fault finding. Moreover, such audit should be done by the medical and para-medical professionals who are the stakeholders in medical management and understand the problems of the patient and doctors. So, medical audit or prescription audit is no way similar to financial audit. In prescription audit the standards should be according the evidence based medical practice. These standards should be achievable in that particular health care system.
The expected standards of an ideal prescription includes:
Prescription must contain the name of the patient , age and gender of the Patient.
Prescription card or note must be dated.
Prescription must be written in a legible manner where the dose, frequency and duration of treatment is clearly mentioned.
Each prescription must be signed by the doctor and doctors identity is clear.

The most common task done by doctors is the writing of prescription. This prescription bears the details of all the drugs including the instructions and name and signature of the physician. If not written appropriately it may loss to the patient including medication errors and adverse drug events
(ADE).
The doctors bears the legal responsibility for prescribing ethically and appropriately.

Prescription audit helps :
1. To prevent the practice of prescribing expensive, unnecessary , irrational and non-essential medicines by the physicians
2. To curtail the practice of writing costly branded drugs when the equally effective cheaper and generic drugs are available
3. To identify shortcomings in prescription writing
4. To reduce omissions in prescription writing by continuous evaluation and feedback to the doctors
5. To measure the extent to which information recorded on Out-Patient Card or In-Patient case file record sheet conforms to the guidelines for prescribing drugs.  Prescription audit measures the compliance with standards set by the health care organization.
6. To articulate measures to improve prescription practices of the doctors.
7.To understand the pattern currently being followed by the doctors and include the drugs in hospital formulary.

The prescription audit improves the prescribing practice in any hospital. Audit is a valuable tool for monitoring compliance to prescribing and administration standards and for encouraging continued improvement in clinical practice.
Physicians, nursing professionals and pharmacists have an important role in continuous evaluation, feedback and improving the quality of health care.
Prescription audit is an important mechanism to improve the quality of healthcare and makes medical care affordable to everyone.

M.Ch. Neurosurgery entrance examination in India

Pattern of examination may change from time to time, but basic priciples remain the same. At present NEET examination has replaced the old M.Ch and D.M. examination held by different colleges and Universities for choosing their own candidates. Even in past, there were varying patterns of entrance examinatins but expectation from the candidate were almost simlar. If your undamentals are clear  may easily adopt to the procedure of entrance examination, and moreover, you will find yourself better placed amng the first year postdoctoral trainees at the college or hospital.
M.Ch. Neurosurgery is the superspeciality course for post doctoral training in General Neurosurgery in India. Many renowned academic medical institutions in India provide training in Neurosurgery.
M.Ch Neurosurgery makes life easy for the surgery post graduates who want to pursue their academic career further after passing M.S.General Surgery examination.
Obtaining M.Ch. Neurosurgery training and degree cuts lot of competition among large number of post graduates in general surgery. Moreover, it is a new begining and an opportunity to focus your surgical career.
During Master in Surgery you gain experience of assisting and operating on different systems of the body. It is good to have a basic knowledge of surgery. But, career in general surgery is albeit challenging as one has to compete with many who acquire surgical skills of operating on hydrocele, hernia, appendix and other abdominal surgeries early in their professional career and start practising. One needs to have some experience after post graduation if he or she wishes to pursue an academic career or get respect among the peers. Further training adds to your competence and provides an opportunity to plan your career as surgeon.
M.Ch Neurosurgery is best way achieve your goal in a standard, well planned, and time bound manner. Once you get through you many problems are over. You become superspecialist and among few elite medical professionals. M.Ch. Neurosurgery training provides you a job for three years, opportunity to master the art of operating over the brain and spine, enhance your academic experience so that you are eligible to become Assistant Professor in Neurosurgery, without any further residency.
The preparation for M.Ch. Neurosurgery is easy but requires planning, perseverance and patience. Read all aspects of neurosurgery with interest: Neuroanatomy, Neurophysiology, Clinical neurological examination, Neuroradiology and neurosurgical conditions like Neuro-trauma, Neurooncology, Pediatric Neurosurgery, Vascular Neurosurgery, etc. One should join a center as a senior resident doctor in Neurosurgery  Department of any hospital where you will be able to learn basics of neurosurgery. This will help you get out of your previous love of general surgery.
You cannot become a Neurosurgeon by still boasting of being a good general surgeon during your post graduate training. Forget your past achievements, preparation for neurosurgery is entirely a new begining. 

Dare to be novice. 
Be hungry to learn more. 
Be grateful to your new colleagues especially the Neursurgery OT, ICU & ward Nursing staffs, OT & ICU technitians, Neuroanesthetists and seniors in the Neurosurgery department. Be open to listen to the patients and their relatives. Every event in Neurosurgery ward or OPD or OT will teach you something. Everyday adds to your experience and now you a superspecialist just by joining a hospital as a resident doctor. Everyday you are creating your impression and this the last and final opportunity for you.

Start with Neuro-anatomy. Learn to know about brain, spinal cord, cranial nerves, skull, spine. Proceed to learn about Neurophysiology like blood supply of brain, CSF formation, etc. 
Neurology learning begins with neurological examination. 
Neuro-radiology is interesting and includes acquanting yourself about the indications and interpretations of X-Ray images, CT scans, MRI, Angiography, PET CT, PET MRI, etc. It is nothing new to you has you might have seen such investigations during your medical graduation or during postgraduate training. Mastering Neuroradiology requires your interest and focus to see minute details and needs your sustained interest & fascination of looking towards such images. You may be surprised to see the pictures of neural structures which you might have thought that such structures are theoretical. A good MRI brain image will show yu the Fornix, Mamillary body, Pituitary talk, superior and inferior collculi. Substantia nigra in the midbrain is very well seen in MRI. So, create your interest in seeing neural structures. 
Any text book of Neurosurgery would provide you a bird eye view of all neurosurgical diseases and their management.
Illustrated Neurology & Neurosurgery by Lindsay Ian Bone is a good book to begin neurosurgery M.Ch preparation. Read each line with interest. Most of the questions of M.Ch. neurosurgery entrance examination can be answered by reading this book. Never underestimate the value of this book.
Clinical Neuroanatomy by Stephen G.Waxman ( 27th edition) by McGraw Hill education, Lange, international edition is another book which I would like to recommend to every aspirant who is preparing for M.Ch neurosurgery. Even this book should be read comprehensively.
Remember that all these books are assets for you as these books will also guide you through out your neurosurgical career.
Start appearing for M.Ch. Neurosurgery entrance examination of reputed institutions like All India Institute of Medical Sciences (AIIMS), Delhi, Govind Ballabh Pant Hospital ( G.B.Pant Hospital, University of Delhi) now G.B.Pant Post Graduate Institute Medical Institute, (GIPMER), Delhi,  Shree Chitra Institute, Trivendrum, P.G.I Chandigarh, NIMHANS Bangalore, Sanjay Gandhi Post Graduate Institute (SGPGI) Lucknow, Uttar Pradesh, Christian Medical College ( CMC ), Vellore and many other institutes who conduct M.Ch Neurosurgery entrance examinations. M.Ch.degree from any institute is of worth pursuing if it is recognized by Medical Council of India. One should not be scared of failing the M.Ch entrance examinations. It will provide you an opportunity to know what is expected from you.

One textbook of Neurosurgery will be required to have an overall concept of Neurosurgery. Ramamurthi & Tandon's Manual of Neurosurgery authored by PN Tandon, R Ramamurthi & PK JainN of Jaypee Publication provides a good concept of every aspect of neurosurgery. Similarly, Handbook of Neurosurgery by Mark S. Greenberg ( 7th Edition) of Thieme publication is an essential companion for all the neurosurgical aspirants & trainees.
Although, it seems very tedious to learn all aspects of neurosurgery theoretically and master the art of neurosurgery also. But, this is possible because this journey of becoming neurosurgeon is very interesting and self motivating. Everyday you add something to your neurosurgical experience. All notes & books will be your companion.

Just to give you an idea about the common questions which are usually asked in entrance exams, I am mentioning some facts for your revision:

Quincke , in 1891, first reported the measurement of intracranial pressure ( ICP) through the lumbar puncture ( LP). So, if question is asked who performed L.P. for the first time? Answer is Quincke.

Quckenstedt established the normal range of normal ICP and demonstrated the effect of changes in ICP with respiration.

Lundberg, in 1960, published his work on the continuous recording of ICP  using indwelling intraventricular catheter and described 3 waveforms: A,B,C.

Cranium is like a rigid sphere & 3 main components inside are brain, blood & CSF occupying 1400 mL, 75 mL & 75 mL of space, respectively. Therefore , any change in the volume of the brain causes reciprocal change in the volume of either blood or CSF.This is the basis of the modified Monro-Kellie doctrine introduced into neurosurgery by Cushing.

Each day in your neurosurgical practice will make you stronger, wiser & confident.

Some commonly asked questions in M.Ch. entrance examinations are mentioned below:

1. Commonest cause of spontaneous intracerebral hematoma in adults?                            

Hypertension

2. Commonest site of spontaneous intracerebral hematoma in adults due to hypertension?

Basal ganglia

3. Commonest cause of subarachnoid haemorrhage (SAH)?                                               

             

             Trauma ( Head Injury)

4. Commonest cause of spontaneous subarachnoid haemorrhage ( SAH) in adults?           

                  

                               Rupture of intracranial aneurysm

5. Maximum incidence of rebeed or re-haemorrhage following aneurysm ruture is

   A. within 24 hour

  B. within 1 week

    C. within 2 weeks

D. First month

The patient who survives the initial haemorrhage of an intracranial aneurysm is at significant risk of 2nd haemorrhage from the aneurysm.

If left untreated, at least 4 percent of patients will experience haemorrhage within the first 24 hour and 19 percent will have re haemorrhage within 2 weeks following the initial haemorrhage. The second haemorrhage has 50 percent. In the first 28 days ( if untreated patient) approximately 30% of patients would re-bleed , of these 70% die.  In the following few months the risk gradually falls off but it never drops below 3.5 per year.

6. Commonest brain tumor?                                                                                                

    Brain metastases are the most common brain tumor.

7. On CT scan of brain , Hounsfield units for fat is about                                                   

-90

Hounsfield unit on CT scan indicates the nature of the structure inside the skull, and relative density of the tissue as compared to brain. On CT scan , Hounsfield unit of water is treated as 0 and it looks black on CT scan.

CSF density is about  +10 to +16. It also looks black as compared to brain tissue.

Fat is about -90. It is more black as compared to CSF.

Hounsfield unit of Bone is approximately more than +300 to +1000. 

Metals look very white on CT scan and a metallic foreign body looks hyperdense +3000. Example is gun shot bullet injury in the brain tissue.

So, about 5 structures look black ( Hypodense ) as compared to brain tissue like Fat, CSF, Air, Pus.

8. Commonest primary brain tumor                                                                                   

Glioma

9. Length of the spinal cord?                                                                                              

           45 centimetre

10. Commonest site of intracranial aneurysm                                                                        

Anterior communicating artery

11. Commonest type of pituitary tumor?                                                                 

 Prolactinoma 

12. What is the size of pituitary Microadenoma                                                    

Less than 1 centimeter 

13.  What is the size of pituitary Macroadenoma                                                     

Size of the pituitary tumor more than 1 cm

14. Positive end expiratory pressure ( PEEP) ventilation is beneficial in of the following situations

A. Head Injury

B. Adult Respiratory Distress Syndrome

B. Both of the above

C. None of the above

Answer is B. In fact PEEP is contraindicated in head injury because it decreases venous return and increases intracranial pressure. Positive end expiratory pressure means pressure in the alveoli at the end of the expiration. It helps to open up the collapsed alveoli in edematous lung of ARDS, and in turn, increases the gaseous exchange at the level of alveoli.

15. Who is regarded as "Father of Modern Neurosurgery"

Harvey Cushing

16. Who invented Bone Wax for stopping bleed from the diploic spaces of skull bones

Victor Horsley

17. Which of the following is the second branch of intracranial part of Internal carotid Artery ( ICA)

      A. Anterior cerebal artery

B. Ophthalmic artery

                                      C. Posterior Communicating artery ( P Com)

             D. Anterior Choroidal artery

Answer is Posterior communicating artery

18. What is the location of Basilar artery to Pons                                                          

                         A. It lies anterior to Pons

     B. Posterior

C. Lateral

D. None

Answer is A, i.e., it lies just anterior to the Pons.

19. Triad of Normal Pressure Hydrocephalus?                                                              

                                                  Gait Apraxia ( Gait Ataxia or gait disturbance) : Difficulty in walking without any weakness of the limbs

Dementia 

and

Urinary incontinence

                                                                                                                                      

                                                                                                                                            

As Neurosurgeon you get lot of respect not because of you are special but because of your consistent endeavour to improve yourself for improving quality of life of many patients who will benefit from your expertize.

                                         

                                                                                   

                                                                              

Spinal Vascular Malformations

Spinal vascular malformations consist of an abnormal connection between the normal arterial and venous pathways. These malformations do not benefit from intervening capillaries. As a result, venous pressure increases and the individual is predisposed to ischemia or haemorrhage.


The vascular lesions of the spinal cord are usually uncommon and may present with the progressive weakness. The spinal cord compression may be due to mass effect of the lesion expansion or  haemorrhage or venous congestion.
Usually the initial investigation for any spinal cord lesion presenting with weakness of limbs is MRI of the spine. MRI may diagnose many lesions. But gold standard investigation for the diagnosis of vascular malformation of spine is spinal angiography.

3 common types of spinal vascular malformations are:

1. Cavernous malformations or Cavernous angiomas or Cavernomas
2. Arteriovenous malformations
3. Arteriovenous fistulas




Cavernous malformations are also known as cavernous angiomas or cavernomas. They constitute about 5% to 12% os spinal vascular malformations. They are aniographically occult , i.e., they may not be seen on angiography. They become symptomatic due to mass effect or due to haemorrhage. They are prone to repeated haemorrhage. So on MRI of the spine a mass occupying lesion may be seen inside the spinal cord hich is surrounded by a gliotic, hemosiderin rim. Patient may present with features of myelopathy due to recuuring hemorrhagic episodes.
Characteristics of intracerebral, brain stem and spinal cavernomas are almost similar.
So, here I have emphasized to describe spinal AVF & spinal AVM in detail.

About a century ago, In 1914, Charles Elsberg performed the first successful operation on a spinal cord malformation. In 1960s, Kendall and Loque used techniques of spinal angiography to define spinal AVMs . In 1977, Kendall and Loque treated these lesions with the less-invasive technique of directly ligating the fistula origin along the dural sleeve, with good results [Kendall].


 Many ways have been proposed to describe and classify these vascular lesions of the spinal cord. But, my aim is to provide a simple yet comprehensive view of these lesions so that any neurosurgical trainee can comprehend the entire subject.

In 1992, Anson and Spetzler classified spinal cord vascular malformations into the following 4 categories:

Type 1: This dural AVF is the most common type of malformation, accounting for 70% of all spinal vascular malformations [Patsalides et al ]. These fistulas are created when a radiculomeningeal artery feeds directly into a radicular vein, usually near the spinal nerve root. Dural AVFs are most commonly found in the thoracolumbar region [ Krings]. Patients with type 1 malformations become symptomatic because the AVF creates venous congestion and hypertension, resulting in hypoperfusion, hypoxia, and edema of the spinal cord. Due to the slow-flow nature of type 1 AVFs, hemorrhage rarely occurs. Most dural AVFs are believed to occur spontaneously, but the exact etiology is still unknown [Krings].

Type I lesions are most frequently found in men between the fifth and eighth decades of life and patients with AVFs are typically older than 40 years. Symptoms increase over an extended period of months to years and include progressive weakness of the legs and concurrent bowel or bladder difficulties. Typically, pain is located in the distal posterior thoracic region over the spine, without a significant radicular component. However, painful radiculopathy may be present. Activity or a change in position may exacerbate symptoms in the thoracic or lumbar region and can result in thoracic spinal cord venous congestion and lower-extremity weakness.

These lesions can be mistakenly diagnosed as spinal stenosis and neurogenic claudication. Foix-Alajouanine syndrome is an extreme form of spinal dural AVF that affects a minority of patients. These patients present with a rapidly progressive myelopathy due to venous thrombosis from spinal venous stasis.

Type 2: ( also referred to as a glomus AVM or racemosum ) type 2 malformations are high flow lesions located within the spinal cord. This Glomus AVM consists of a tightly compacted group of arterial and venous vessels (nidus) inside a short segment of the spinal cord. Multiple feeding vessels from the anterior spinal artery and/or the posterior spinal circulation typically supply these AVMs. The abnormal vessels are intramedullary in location, although superficial nidus compartments can reach the subarachnoid space [Krings]. Type 2 AVMs are the most commonly encountered intramedullary vascular malformations, representing about 20% of all spinal vascular malformations. These lesions usually present in younger patients with acute neurologic deterioration secondary to their location, which is usually the dorsal cervicomedullary region. The mortality rate related to type 2 malformation is reported at 17.6%. After initial hemorrhage, the rebleed rate is 10% within the first month and 40% within the first year.

Type 3: These malformations are arteriovenous abnormalities of the spinal cord parenchyma fed by multiple vessels. These juvenile malformations are extensive lesions with abnormal vessels that can be both intramedullary and extramedullary in location. These lesions are typically found in young adults and children.

Type 4: Also known as pial AVFs, these malformations are intradural extramedullary AVFs on the surface of the cord that result from a direct communication between a spinal artery and a spinal vein without an interposed vascular network. They are usually seen in patients who are between their third and sixth decade of life.

Spinal malformations can also broadly be separated into 2 subgroups. Spinal vascular malformations can also be classified into 2 general groups. One group consists of the spinal dural fistulas (type 1), and the other group has intradural pathology (types 2-4).


Investigations
CT scanning may demonstrate dilated vessels in the thecal sac, but findings are usually normal. If a patient presents with symptoms of subarachnoid hemorrhage, CT scanning demonstrates blood in the spinal fluid.


Myelography findings, with or without CT, show dilated vessels in the intradural space. This imaging modality is very sensitive and shows these abnormalities in detail. This is an invasive procedure that requires injection of a contrast agent into the thecal sac. Postprocedure headaches are not uncommon.


MRI is a noninvasive imaging modality. The soft tissue and neural elements are visualized in detail with this technique. Dilated intradural vessels can be seen as flow voids or can be seen filling with contrast. Edema or hemorrhage in the spinal cord parenchyma can be assessed. The exact fistula site cannot be localized.


MRI of dural AVFs on the thoracolumbar junction usually shows serpiginous vessels in the intradural compartment, along with vasogenic edema in the spinal cord. Intradural vascular spinal malformations appear as lesions in the spinal parenchyma.


MRA or CTA are noninvasive modalities being used to identify any abnormal vessels. However, the resolution of these modalities is not to yet high enough.


Arteriography is the gold standard modality for visualizing arteriovenous malformations (AVMs). This is a dynamic study that allows visualization of the pathology in real time, allowing assessment of high-flow versus low-flow AVMs. In addition, the location of the fistula can be visualized. Arteriography is an invasive procedure that may cause morbidity such as spinal cord ischemia, cerebral vascular accident, and vascular dissection.


Spinal MRI is first-line screening method to detect spinal vascular malformations. If a spinal vascular malformation is still suspected, digital subtraction angiography (DSA) must be performed to display the very small vessels of the spinal cord. As DSA is an invasive procedure, an MR angiography (MRA) or CT angiography (CTA) can be used to determine the spinal cord level of the feeding artery.

Treatment of SVMs
The ideal treatment of spinal vascular malformation is to obliterate the nidus without damaging the spinal vascular blood supply and spinal cord. It may be achieved with open surgery, endovascular methods, or a combination of both. Stereotactic radiosurgery is a newer modality of treatment.

The present surgical treatment options include open surgical ligation or resection of the malformation, endovascular occlusion, spinal radiation, or a combination of these techniques.

Surgical excision is the mainstay of treatment of cavernomas.

Dural arteriovenous fistulas (AVFs), type 1, can be treated with either open or endovascular ligation. Both techniques yield excellent results, with occlusion rates reported as higher than 80%. The benefit of the endovascular technique is that it is less invasive. If the patient has multiple sites of fistula formation, open ligation is more appropriate because all feeding vessels may be ligated under direct vision. Open surgery is necessary if the arterial feeding vessel is impossible to access because of tortuous vascular anatomy or if the vessel supplies blood to healthy regions of the spinal cord [Özkan, Lin, Signorelli, Clark, Kirsch, Maimon]

Intradural AVMs (types 2-4) are typically best treated with endovascular surgery and, if required, open surgery and resection.

Treatment options are dictated by the location of the lesion, the patient's medical condition, and the risk-versus-benefit ratio. The most important factor in determining treatment options is the presence of intramedullary or extramedullary shunting. Malformations that are subpial in location are less likely to be cured. These are usually supplied by subcommissural branches of the anterior spinal artery (ASA). Lesions on the surface of the spinal cord that are supplied by circumferential branches of the ASA may be safely treated with either embolization or surgery.


The new generation of liquid embolic material and microcatheters has made interventional treatment of spinal AVMs safer, with better results [Warakaulle , Corkill].The goal of any intervention is to eliminate the shunt. Microcatheterization is of paramount necessity in achieving effective results. Delivery of embolic material to the nidus of the lesion reduces the arteriovenous malformation (AVM) and reduces the risk of inadvertent embolization of normal vessels.


When preoperative embolization is planned, polyvinyl alcohol microparticles (PVAs) are a reasonable choice of embolic material. They are also useful for embolization of type 2 AVMs. The advantages of PVA are that embolization may be performed at a more proximal location and that the size of particle can be determined depending on the size of the lesion and its collaterals. The goal of treatment with either agent is to provide distal occlusion of the nidus. Proximal occlusion results in collateral reconstitution, with little hope of cure.


Procedure is done under general anesthesia and neurophysiologic monitoring. Somatosensory-evoked potentials (SSEPs) help in assessing spinal cord function. Motor-evoked potentials (MEPs) are also useful when a spinal AVM is supplied by the ASA.





References

1. Harrop JS. Vascular malformations of the spinal cord.
                  http://emedicine.medscape.com/article/248456-overview
2. Anson JA, Spetzler RF. Interventional neuroradiology for spinal pathology. Clin Neurosurg. 1992. 39:388-417.
3. Patsalides A, Santillan A, Knopman J, et al. Endovascular management of spinal dural arteriovenous fistulas. J NeuroIntervent Surg. 2010. 3(1):80-84.
4. Krings T. Vascular Malformations of the Spine and Spinal Cord : Anatomy, Classification, Treatment. Klin Neuroradiol. 2010 Feb 28.
5. Özkan N, Kreitschmann-Andermahr I, Goerike SL, Wrede KH, Kleist B, Stein KP, et al. Single center experience with treatment of spinal dural arteriovenous fistulas. Neurosurg Rev. 2015 Oct. 38 (4):683-92.
6. Kendall BE, Loque V. Spinal epidural angiomatous malformations draining into intrathecal veins. Neuroradiology. 1977. 13:181-189.
7. Aadland TD, Thielen KR, Kaufmann TJ, et al. 3D C-arm conebeam CT angiography as an adjunct in the precise anatomic characterization of spinal dural arteriovenous fistulas. AJNR Am J Neuroradiol. 2010 Mar. 31(3):476-80.
8. Lin N, Smith ER, Scott RM, Orbach DB. Safety of neuroangiography and embolization in children: complication analysis of 697 consecutive procedures in 394 patients. J Neurosurg Pediatr. 2015 Oct. 16 (4):432-8.
9. Signorelli F, Della Pepa GM, Sabatino G, Marchese E, Maira G, Puca A, et al. Diagnosis and management of dural arteriovenous fistulas: a 10 years single-center experience. Clin Neurol Neurosurg. 2015 Jan. 128:123-9.
10. Clark S, Powell G, Kandasamy J, Lee M, Nahser H, Pigott T. Spinal dural arteriovenous fistulas--presentation, management and outcome in a single neurosurgical institution. Br J Neurosurg. 2013 Aug. 27 (4):465-70.
11. Kirsch M, Berg-Dammer E, Musahl C, Bäzner H, Kühne D, Henkes H. Endovascular management of spinal dural arteriovenous fistulas in 78 patients. Neuroradiology. 2013 Feb. 55 (3):337-43.
12. Warakaulle DR, Aviv RI, Niemann D, Molyneux AJ, Byrne JV, Teddy P. Embolisation of spinal dural arteriovenous fistulae with Onyx. Neuroradiology. 2003 Feb. 45(2):110-2.
13. Corkill RA, Mitsos AP, Molyneux AJ. Embolization of spinal intramedullary arteriovenous malformations using the liquid embolic agent, Onyx: a single-center experience in a series of 17 patients. J Neurosurg Spine. 2007 Nov. 7(5):478-85.
14. Veznedaroglu E, Nelson PK, Jabbour PM, Rosenwasser RH. Endovascular treatment of spinal cord arteriovenous malformations. Neurosurgery. 2006 Nov. 59(5 Suppl 3):S202-9; discussion S3-13.
15. Schuette AJ, Cawley CM, Barrow DL. Indocyanine green videoangiography in the management of dural arteriovenous fistulae. Neurosurgery. 2010 Sep. 67(3):658-62; discussion 662.
16. Bridwell KH, DeWald RL. The textbook of Spinal Surgery , 3rd ed. ( Wolters Kluwer/ Lippincott, Williams & Wilkins, 2011.