Wednesday 28 August 2013

Pediatric Hydrocephalus

Hydrocephalus is a condition in which excess of CSF accumulates within the ventricular system leading to increased intracranial pressure. Hydrocephalus occurs due to imbalance between the production of CSF and its absorption.
Hydrocephalus in children is a very common problem encountered by pediatricians , surgeons and neurosurgeons.The folic acid vitamin supplements in antenatal period and antenatal care including ultrasonography have diminished the incidence of neural tube defects and pediatric hydrocephalus.
The clinical presentation of pediatric hydrocephalus are those of raised intracranial pressure, which vary with age.
An infant with open sutures usually present with a gradually increasing head circumference. The most common finding will be the large head size.Irritability, vomiting , eye movement abnormalities like downward deviation of the eyes ( " sunsetting" sign ) or the sixth nerve paresis are other common finding. The percussion over the skull may produce a "cracked pot sign." The veins of the scalp may be very prominent. here will be sutural diastasis. Anterior fontenelle is bulging and brain pulsations may be obvious.
As the child gets older and sutures fuse, the presentation differs. The head size may still be large for that age. Child may complain of headache , nausea and vomiting . On examination there may be papilledema and visual deficit. papilledema may occur in long standing cases.
Presentation beyond the first few years of life usually suggests hydrocephalus secondary to an acquired disorder such as tumor, infection ( meningitis) or head injury.
The common causes of Congenital hydrocephalus( Hydrocephalus presents soon after birth) are Aqueduct stenosis, Dandy Walker syndrome, Holoprosencephaly, generalized malformation of brain development.
Myelomeningocele and meningocele may be associate with Arnold Chiari malformation and Hydrocephalus.
Other common causes of hydrocephalus in pediatric age group are:
           Arachnoid cyst,
           Post hemorrhagic hydrocephalus due to intraventricular hemorrhage in a premature infant
           Hydrocephaus associated with brain tumors like Craniopharyngioma,  Pineal tumor, Medulloblastoma and posterior fossa Ependymoma.
           Post traumatic hydrocephalus
           Post meningitic hydrocephalus ( Pyogenic Meningitis, Viral Meningitis or Tubercular ) or post infective like granulomas compressing over the ventricle ( Tuberculoma, Neurocysticercus) or abcess.
          Choroid plexus papilloma causes hydrocephalus mainly due to excessive production of CSF.
 Management of Hydrocephalus may begin with the antenatal care and advising ultrasonography.
 MRI of the  brain and spine should be done  if there is any suspicion of Arnold Chiari malformation to diagnose associated split cord malformation, Syringomyelia, congenital dermal sinus.
Monitoring of the patient and conservative trial of treatment with cerebral decongestants are sufficient to treat a majority of pediatric patients with hydrocephalus and surgery for the CSF diversion procedure is not required.
Ventriculoperitoneal Shunt surgery ( VP shunt) is very common surgery for the treatment of hydrocephalus. Endoscopic third ventriculostomy is another option to treat hydrocephalus where an opening is made in the floor of third ventricle and CSF pathway is opened from third ventricle to the pre pontine cistern.

Who can be a Pediatric Neurosurgeon?

Pediatric Neurosurgery is a subspecialty of neurosurgery. Almost all the resident doctors, trainees in neurosurgery  and qualified  neurosurgeons are treating the neurosurgical conditions in pediatric age group of patients. Congenital hydrocephalus,Meningocele are very common peditric neurosurgical problems. Almost all trainees and neurosurgeons are able to ventriculoperitoneal shunt surgery and excision and repair of the meningocele.
To master this subspecialty of neurosurgery one should have an overview of the common conditions which occur in neonated and children.
The management of Congenital hydrocephalus may begin in the prenatal stage. Congenital hydrocephalus or meningocele or meningomyelocele may be detected during the antenatal check up of the fetus with ultrasonography. The new born may present with the large head or a sac over the spine and ventriculoperitoneal shunt or excision and repair of meningocele may be required at birth.
Spinal dysraphism, Congenital dermal sinus, and Encephalocele are the common pediatric neurosurgical problems at birth and should further be investigated with MRI.
At later stage a child may present with hydrocphalus, brain tumors, spine tumors, infections of the brain. The presentations of such diseases are very often different from that of adults. Like incresing head size, irritability, vomiting may be the symptom oh hydrocephalus, difficulty in walking or pain during walking or difficulty in urination can be a presentation of occult spinal dysraphism. A child may lose vision even before somebody notices the symptoms of craniopharyngioma or a malignat posterior fossa tumor like edulloblastoma.
Craniosynostosis is the premature fusion of cranial sutures leading to deformed head and features of raised ICT. Oxycephaly is the fusion of all cranial sutures with rounded haed and Turricephaly is the tower like head. Plagiocephaly leads to asymmetric head size.
Craniopharyngima and pituitary tumors may present with stunted growth , visual deficits or hormonal imbalance.
Posterior fossa tumors like medulloblastoma or ependymoma may present with hydrocephalus and difficulty in walking.
Dermoid of the spine is the commonest tumor of the spine in children. The Meningomyelocele patients should also be screened for other congenital abnormalities  including cranial MRI and spinal MRI for detecting hydrocephalus, Arnold Chiari Malformation, congenital dermal sinus, split cord malformations.
Endoscopic surgery has become another adjunct for comprehensive management of pediatric neurosurgical conditions , especially Endoscopic third ventriculostomy ( Hydrocephalus due to Aqueductal stenosis), & removal of intra-ventricular tumors.
So, further training in Pediatric Neurosurgery could  be of great help to the Neurosurgeons to become Pediatric Neurosurgeon.


Tuesday 20 August 2013

Memory, Cognition, Dementia


Memory is the process in which information is encoded ( registered) , stored and retrieved.

Brain areas involved in the neuroanatomy of memory are the hippocampus , striatum, mammillary bodies.

Disorders of memory  and treatment

Loss of memory is known as amnesia. Amnesia can result from extensive damage to : (a) the regions of medial temporal lobe, or ( b) midline diencephalic structures, specifically the dorsomedial nucleus of the thalamus & the mammillary bodies of the hypothalamus.

Many diseases like Alzheimer’s disease, Parkinson’s disease, vascular dementia, head injury, chronic subdural hematoma, Wernicke encephalopathy ( alcoholism ), Brain tumors can  affect the memory in a person who were otherwise normal before the onset of the disease . There are certain other diseases which affect the memory like Pick’s disease, CJD, H. Chorea, Wilson’s disease.
There are many drugs like piracetam, citicholine,  vitamine E, Cyanocobalmine , Methylcobalamine, folic acid, alpha lipoic acid, omega fatty acids, cerebroprotein lysate, galantamer, Memantine, etc which help in improving cognition and neuroprotection.
Cholinesterase inhibitors are used in the treatment of Alzheimer's disease ( Donepezil).

Even an old patient presents with a triad of symptoms: Dementia ( diminished memory/ cognitive impairment), Gait disturbance [difficulty in walking (Gait apraxia means inability to walk inspite of normal power in both the lower limbs)], urinary incontinence. Then CT scan or MRI of the brain should be advised which may reveal the diagnosis of Normal Pressure Hydrocephalus (NPH). The treatment of NPH is neurosurgery in the form of theco-peritoneal shunt or Low Pressure Ventriculo-peritoneal shunt. Low pressure ventriculoperitoneal shunt surgery improves memory in patients with normal pressure hydrocephalus (NPH).
Another cause of dementia which can be treated surgically is Chronic subdural hematoma (Chronic SDH). Bur hole evacuation of the hematoma is the treatment for chronic SDH.

Neurosurgical evacuation of chronic subdural hematoma improves the memory in a chronic SDH patient. 
Neurosurgical interventions like cartid endarterectomy ( CEA) or neurointervention like carotid stenting can help in treating vascular dementia due to carotid artery stenosis.
Moya moya disease may also present with dementia and it can be treated with neurosurgery.
Recently, neurosurgical intervention like Deep brain stimulation ( DBS ) has been reported to treat the dementia.Deep brain stimulation uses a technique in whch microelectrodes are introduced deep inside the brain to stimulate Nucleus basalis of Meynert, Fornix and entorhinal cortex in Alzheimer's disease. 
 In some cases, the Dural arteriovenous fistula ( AVF) can cause dementia. Dural AVFs are vascular malformations and in the past surgical obliteration was the treatment of choice but now a days endovascular embolization has become the first line treatment.
Stem cell transplantation is an avenue of research in treatment of Huntington chorea.

How to improve memory?

As in common  practice  rote learning , intense memorization, repetition and concentration are the ways to enhance memory. There are many other factors which influence memory.

A very useful link with details of how to improve memory:

http://www.helpguide.org/life/improving_memory

The human brain has an astonishing ability to adapt and change—even into old age. This ability is known as neuroplasticity. With the right stimulation, your brain can form new neural pathways, alter existing connections, and adapt and react in ever-changing ways.

Exercise increases oxygen to your brain and reduces the risk for disorders that lead to memory loss, such as diabetes and cardiovascular disease. Exercise may also enhance the effects of helpful brain chemicals and protect brain cells.

When you’re sleep deprived, your brain can’t operate at full capacity. Sleep is necessary for memory consolidation, with the key memory-enhancing activity occurring during the deepest stages of sleep.

Active social life , healthy social interactions , playful activities.

You’ve heard that laughter is the best medicine, and that holds true for the brain as well as the body. Unlike emotional responses, which are limited to specific areas of the brain, laughter engages multiple regions across the whole brain.

Stress is one of the brain’s worst enemies. Over time, if left unchecked stress destroys brain cells and damages the hippocampus, the region of the brain involved in the formation of new memories and the retrieval of old ones.

Meditation helps improve many different types of conditions, including depression, anxiety, chronic pain, diabetes, and high blood pressure. Meditation also can improve focus, concentration, creativity, and learning and reasoning skills.

In addition to stress, depression, anxiety, and chronic worrying can also take a heavy toll on the brain. In fact, some of the symptoms of depression and anxiety include difficulty concentrating, making decisions, and remembering things. If you are mentally sluggish because of depression or anxiety, dealing with the problem will make a big difference in your cognitive abilities, including memory.

Just as the body needs fuel, so does the brain. You probably already know that a diet based on fruits, vegetables, whole grains, “healthy” fats (such as olive oil, nuts, fish) and lean protein will provide lots of health benefits, but such a diet can also improve memory. But for brain health, it’s not just what you eat—it’s also what you don’t eat. The following nutritional tips will help boost your brainpower and reduce your risk of dementia:

  • Get your omega-3s. More and more evidence indicates that omega-3 fatty acids are particularly beneficial for brain health. Fish is a particularly rich source of omega-3, especially cold water “fatty fish” such as salmon, tuna, halibut, trout, mackerel, sardines, and herring. In addition to boosting brainpower, eating fish may also lower your risk of developing Alzheimer’s disease. If you’re not a fan of seafood, consider non-fish sources of omega-3s such as walnuts, ground flaxseed, flaxseed oil, winter squash, kidney and pinto beans, spinach, broccoli, pumpkin seeds, and soybeans.
  • Limit calories and saturated fat. Research shows that diets high in saturated fat (from sources such as red meat, whole milk, butter, cheese, sour cream, and ice cream) increase your risk of dementia and impair concentration and memory.
  • Eat more fruit and vegetables. Produce is packed with antioxidants, substances that protect your brain cells from damage. Colorful fruits and vegetables are particularly good antioxidant "superfood" sources. Try leafy green vegetables such as spinach, broccoli, romaine lettuce, Swiss chard, and arugula, and fruit such as bananas, apricots, mangoes, cantaloupe, and watermelon.
  • Drink green tea. Green tea contains polyphenols, powerful antioxidants that protect against free radicals that can damage brain cells. Among many other benefits, regular consumption of green tea may enhance memory and mental alertness and slow brain aging.
  • Drink wine (or grape juice) in moderation. Keeping your alcohol consumption in check is key, since alcohol kills brain cells. But in moderation (around 1 glass a day for women; 2 for men), alcohol may actually improve memory and cognition. Red wine appears to be the best option, as it is rich in resveratrol, a flavonoid that boosts blood flow in the brain and reduces the risk of Alzheimer’s disease. Other resveratrol-packed options include grape juice, cranberry juice, fresh grapes and berries, and peanuts.

For mental energy, choose complex carbohydrates

Just as a racecar needs gas, your brain needs fuel to perform at its best. When you need to be at the top of your mental game, carbohydrates can keep you going. But the type of carbs you choose makes all the difference. Carbohydrates fuel your brain, but simple carbs (sugar, white bread, refined grains) give a quick boost followed by an equally rapid crash. There is also evidence to suggest that diets high in simple carbs can greatly increase the risk for cognitive impairment in older adults. For healthy energy that lasts, choose complex carbohydrates such as whole-wheat bread, brown rice, oatmeal, high-fiber cereal, lentils, and whole beans. Avoid processed foods and limit starches (potato, pasta, rice) to no more than one quarter of your plate.

Give your brain a workout

By the time you’ve reached adulthood, your brain has developed millions of neural pathways that help you process information quickly, solve familiar problems, and execute familiar tasks with a minimum of mental effort. But if you always stick to these well-worn paths, you aren’t giving your brain the stimulation it needs to keep growing and developing. You have to shake things up from time to time! Try taking a new route home from work or the grocery store, visiting new places at the weekend, or reading different kinds of books

Memory, like muscular strength, requires you to “use it or lose it.” The more you work out your brain, the better you’ll be able to process and remember information. The best brain exercising activities break your routine and challenge you to use and develop new brain pathways. Activities that require using your hands are a great way to exercise your brain. Playing a musical instrument, juggling, enjoying a game of ping pong (table tennis), making pottery, knitting, or needlework are activities that exercise the brain by challenging hand-eye coordination, spatial-temporal reasoning, and creativity.

The brain exercising activity you choose can be virtually anything, so long as it meets the following three criteria:

  1. It’s new. No matter how intellectually demanding the activity, if it’s something you’re already good at, it’s not a good brain exercise. The activity needs to be something that’s unfamiliar and out of your comfort zone.
  2. It’s challenging. Anything that takes some mental effort and expands your knowledge will work. Examples include learning a new language, instrument, or sport, or tackling a challenging crossword or Sudoku puzzle.
  3. It’s fun. Physical and emotional enjoyment is important in the brain’s learning process. The more interested and engaged you are in the activity, the more likely you’ll be to continue doing it and the greater the benefits you’ll experience. The activity should be challenging, yes, it should also be something that is fun and enjoyable to you. Make an activity more pleasurable by appealing to your senses—playing music while you do it, or rewarding yourself afterwards with a favorite treat, for example.

Use mnemonic devices to make memorization easier

Mnemonics are clues of any kind that help us remember something, usually by helping us associate the information we want to remember with a visual image, a sentence, or a word.

Mnemonic device
Example
Visual image – Associate a visual image with a word or name to help you remember them better. Positive, pleasant images that are vivid, colorful, and three-dimensional will be easier to remember.
To remember the name Rosa Parks and what she’s known for, picture a woman sitting on a park bench surrounded by roses, waiting as her bus pulls up.
Acrostic (or sentence) - Make up a sentence in which the first letter of each word is part of or represents the initial of what you want to remember.
The sentence “Every good boy does fine” to memorize the lines of the treble clef, representing the notes E, G, B, D, and F.
Acronym – An acronym is a word that is made up by taking the first letters of all the key words or ideas you need to remember and creating a new word out of them.
The word “HOMES” to remember the names of the Great Lakes: Huron, Ontario, Michigan, Erie, and Superior.
Rhymes and alliteration - Rhymes, alliteration (a repeating sound or syllable), and even jokes are a memorable way to remember more mundane facts and figures.
The rhyme “Thirty days hath September, April, June, and November” to remember the months of the year with only 30 days in them.
Chunking – Chunking breaks a long list of numbers or other types of information into smaller, more manageable chunks.
Remembering a 10-digit phone number by breaking it down into three sets of numbers: 555-867-5309 (as opposed to5558675309).
Method of loci – Imagine placing the items you want to remember along a route you know well or in specific locations in a familiar room or building.
For a shopping list, imagine bananas in the entryway to your home, a puddle of milk in the middle of the sofa, eggs going up the stairs, and bread on your bed.


6 Mnemonic devices
Visual image - Associate a visual image with a word or name to help you remember them better. Positive, pleasant images that are vivid, colorful, and three-dimensional will be easier to remember.
Example: To remember the name Rosa Parks and what she’s known for, picture a woman sitting on a park bench surrounded by roses, waiting as her bus pulls up.
Acrostic (or sentence) - Make up a sentencein which the first letter of each word is part of or represents the initial of what you want to remember.
Example: The sentence “Every good boy does fine” to memorize the lines of the treble clef, representing the notes E, G, B, D, and F.
Acronym - An acronym is a word that is made up by taking the first letters of all the key words or ideas you need to remember and creating a new word out of them.
Example: The word “HOMES” to remember the names of the Great Lakes: Huron, Ontario, Michigan, Erie, and Superior.
Rhymes and alliteration - Rhymes, alliteration (a repeating sound or syllable), and even jokes are a memorable way to remember more mundane facts and figures.
Example: The rhyme “Thirty days hath September, April, June, and November” to remember the months of the year with only 30 days in them.
Chunking - Chunking breaks a long list of numbers or other types of information into smaller, more manageable chunks.
Example: Remembering a 10-digit phone number by breaking it down into three sets of numbers: 555-867-5309 (as opposed to5558675309).
Method of loci - Imagine placing the items you want to remember along a route you know well or in specific locations in a familiar room or building.
Example: For a shopping list, imagine bananas in the entryway to your home, a puddle of milk in the middle of the sofa, eggs going up the stairs, and bread on your bed.

Tips for enhancing your ability to learn and remember

  • Pay attention. You can’t remember something if you never learned it, and you can’t learn something—that is, encode it into your brain—if you don’t pay enough attention to it. It takes about eight seconds of intense focus to process a piece of information into your memory. If you’re easily distracted, pick a quiet place where you won’t be interrupted.
  • Involve as many senses as possible. Try to relate information to colors, textures, smells, and tastes. The physical act of rewriting information can help imprint it onto your brain. Even if you’re a visual learner, read out loud what you want to remember. If you can recite it rhythmically, even better.
  • Relate information to what you already know. Connect new data to information you already remember, whether it’s new material that builds on previous knowledge, or something as simple as an address of someone who lives on a street where you already know someone.
  • For more complex material, focus on understanding basic ideas rather than memorizing isolated details. Practice explaining the ideas to someone else in your own words.
  • Rehearse information you’ve already learned. Review what you’ve learned the same day you learn it, and at intervals thereafter. This “spaced rehearsal” is more effective than cramming, especially for retaining what you’ve learned.


GET RID OF BAD MEMORIES

Get rid of bad memories in order to create space for memories of pleasant experiences in future. Is it really  possible for somebody to selectively delete the scars of the past bad experiences?
Forgiveness, Yoga, a positive approach, an optimistic attitude are definitely helpful in fading the scars of the past memories. 
A frequent exposure to bad situations may further deteriorate the situation, so if possible, one should avoid the repetition of past  unpleasant situations. A fresh and novice place or circumstance is like a blank page where one can write an entirely new beautiful story.
Deliberately avoiding of a particular fact is not a lie. If someone wants not to tell the truth then he or she is not a coward. Many truths may be eternal and like rule of thumb like any person who takes birth will die one day. In fact, we all will die sooner or later, but biggest pleasure is thinking about the life. By deliberately avoiding this fact that death is certain, it is easy to do things positively and help in creating good life experiences like pleasures of wealth, health, knowledge , charity, etc.
Distancing from the bad event also helps to delete the past bad memory. It helps somebody to heal. The distancing may in terms of place, person or time. Time is the biggest healer. As time passes the agony of the trauma gradually subsides. Similarly , if you remain away from a person associated with a  bad memory, gradually the bad memory fades and it will not trouble you. And, definitely the pleasant experiences will overshadow it.
Your attitude makes the difference. Same event affects the different person differently depending on their attitude.  For a  positive person, failure is an opportunity to take rest, review , learn and then again pursue with extra and renewed vigour and achieve extraordinary success by learning from mistakes. For that person the bad memory is just like a warning signage. And, that person is fully aware of the situation and becomes the only solver of that ugly situation. So, he or she becomes the role model for the people who are facing that problem in their life or business.
Self belief , trust yourself and trust someone else . Love yourself and love somebody else also. Everybody is not same. If you have been harmed donot harm others. Negativity is perpetual it means that to become a negative person you need not to make effort. It is like decay. But to become a positive and lovable  person you have to make lot of effort. Be happy, love being happy , believe in positivity like non-violence, charity, education, faith, and compassion. Gradually you will get reward of your actions and you will be in the company of good people with positive attitude and you will need not to make lot of efforts for remaining nice.
Many persons with  violent  and aggressive childhood  have changed themselves in amazing sportpersons, especially boxers. This phenomenon is is called sublimation. 

As a human being we are albeit different from other animals in terms of intellect , memory and ability to adopt.
I personally feel that all of us suffer from selective dementia. I am using this term for the first time as my own hypothesis. As we ignore certain learned activies or we do not want to learn then it becomes gradually difficult  and almost impossible to recall. For example, if someone ignores learning music or stops practicing mathematics then it becomes more difficult to do such things in later stage of life. It starts as a voluntary activity ,i.e., deliberately ignoring or avoiding and later it becomes unvoluntary action. In the similar way if somebody will ignore a bad experience it will gradually  just remain as a small piece of information placed in the recycle bin of the large capacity software of the brain.

Some people tackle the problem head-on. Take  the bull by the horns. Face the problem straightway and  win over it . No longer ashamed of what happened to them. Not allowing the incidence affect their performance. Tell the world the real truth and put off the burden off their head. I observe that it is a very common phenomenon in the society. Most of the  leaders and role models of the society had sooner or later realized that they were not the only one who had such problem in the past. Getting strength to tell the truth automatically end the fear. A coward and fearful person immediately becomes a role model and lot of people start relating with these iconic personalities . Many people start admiring these  heros. A stigma becomes an opportunity to lead. World is full of such examples. Many high achievers never mince words in expressing their hardship and bad experience in the past.

Sources:
Wikipedia

 

Monday 19 August 2013

DANDY WALKER SYNDROME ( DWS )


What is Dandy Walker Syndrome?

Dandy Walker syndrome ( DWS ) represents a congenital malformation characterized by agenesis or hypoplasia of the cerebellar vermis, cystic dilation of the fourth ventricle, and enlargement of the posterior fossa with or without hydrocephalus.

Who first described this condition?

First autopsy descrpition  in 1887 by Sutton.

First to realize an association between hydrocephalus and cystic fourth ventricular dilation were Dandy & Blackfan in 1914

Dandy in 1921 & Taggart & Walker in 1942 related it to congenital atresia of the fourth ventricular exit foramina.

Benda in 1954 first used the term DWS.

Studies by D'Agostino in 1963 and Hart et al in 1972 further defined the characteristic triad of Dandy-Walker malformation, as follows:

  • Complete or partial agenesis of the vermis
  • Cystic dilatation of the fourth ventricle
  • An enlarged posterior fossa with upward displacement of lateral sinuses, tentorium, and torcular herophili.

What is the etiopathogenesis?

Cerebellum development  begins in the 9th week of gestation when the genesis of the cerebellar hemispheres occurs from the rhombic lips. Subsequently , the hemispheres fuse to form the rhombic lips . Subsequently, the cerebellar  hemispheres fuse to form vermis. The abnormal development at this stage may lead to non regression of posterior medullary velum, absence of vermis, failure of development of foramen of Magendie.

What are the clinical features?

DWS occurs in 1 in 30,000 newborns with the highest incidence in infants. The presentation may me delayed . Usually presents with macrocrania, delayed milestones. It is one of the differential diagnosis of pediatric hydrocephalus.

What are the radiological features?

Elevated torcular Herophili  on Plain radiography ( Bucy’s sign)

Featal ultrasound, or post natal ultrasound or MRI or CT scan

Enlarged fourth ventricle and posterior fossa, elevated location of the transverse venous sinuses and their confluence.

Absence of cerebellar vermis and hypoplasia of the cerebellar hemispheres.
 

What is the treatment?
Diversion of CSF through shunting. Options include (1) shunting the supratentorial compartment(ventriculoperitoneal shunt) , (2) shunting the cerebellar cyst ( Cysto peritoneal shunt) ,or (3) shunting both compartments.

 
Sources:
Chapter DWS, Authors; Ondrej Choutka & Francesco T.Mangano.  Youman’s Neurological Surgery, H.Richard Winn,  6th Edition( Elsevier Saunders)
Wikipedia
Medscape reference

Sunday 4 August 2013

Deep Brain Stimmulation ( DBS )

Deep Brain stimulation is a technique in which deep part of brain is stimulated with the surgically placed electrodes. This technique is now a well established procedure in cases of Parkinsonism. Electrical stimulation of the subthalamic nucleus (STN) is an accepted treatment for advanced Parkinson disease (PD). To place electrode in the the deeper part of brain , a surgical procedure needs to be very precise.
So a preoperative imaging is required to localize the lesion.
Step 1.Stereotactic frame is fixed over the head of the patient.
So, the DBS procedure begins with placing a stereotactic frame fixed over the head.
For example
(Source)
Leksell‑Stereotactic‑Frame.jpg elektaindia.co.inShare
 


A stereotactic frame applied over the head. The application of this frame is very easy and it does not require general anesthesia. Local anesthetic agent may be used and patient remains conscious after the application of the frame.
Step 2. Patient is shifted to the MRI room to calculate the distance of the subthalamic nucleus from the arc of the stereotactic frame. So the length of the electrode can be measured. Now the neurosurgeon knows the distance , direction and depth of the target on X-axis, Y - axis and Z-axis, and actually is the aim of stereotaxy.

Fig 2.

Magnified area of interest in the sagittal (A), coronal (B), and axial (C) planes. R, red nucleus; SN, substantia nigra; ZI, zona incerta; CI, capsula interna; T, thalamus; LV, lateral ventricle; STN, subthalamic nucleus.
(Source AJNR )

Step 3. Two Burr holes are made under local anesthesia , usually 3 cm lateral to midline and just anterior to the coronal suture on either side ( In Frontal bone).
Step 4. After initial burr holes, dura is coagulated a very thin micro electrode is introduced in the brain towards the subthalamic nucleus.
Step 5. Deep brain stimulation of the target site to see the pattern of dischrges  from the subthalamic nucleus. When an expected pattern or discharges or wave pattern is seen or heard , neurosurgeon or neurologist becomes sure that the electrode is in the subthalamic nucleus. Then the scalp is closed in layers and electrodes remain in place. Till this procedure patient usually remains awake and alert and may respond the the electrode stimulation .
Fig 3.

Sample intraoperative microelectrode recording from a single neuron at the center of the STN calculated with preoperative 3T MR imaging. A, Real-time electrophysiologic recording. B, Single-cell spike registration screen
(Source AJNR )

Step 6. Then a small sized neurostimulator is connected to the electrodes. For Placing the neurostimulator a subcutaneous tunnel is made and a subcutaneous pouch is made just below the collar bone. This procedure requires General anesthesia. The neurostimulator of Medtronic company is shown below ( White in color).
Step 7. Programming of the stimulation.
dbs-family-md-lg

 (Source : Medtronic Product information online)

I have written only about the use of DBS in Parkinson disease to give a very simple overview of the procedure. Now, there are many indications for DBS. This is very easy procedure and any neurosurgical center can adopt this procedure. This technique has great potential. This procedure requires a stereotactic frame and  MRI. There are only a few neurosurgical complications which are almost same as burr hole evacuation of chronic SDH.

Saturday 3 August 2013

Meningioma: A brief and simplified description


Meningiomas account for about 25% of primary intracranial tumours.  Meningiomas occur most commonly in middle-aged and elderly patients with a peak during the sixth and seventh decades. The term meningioma was coined by Harvey Cushing in 1922 when he reported 85 cases of meningioma. In 1932 Cushing & Eisenhardt reported a series of 313 patients with meningioma encountered between 1903 & 1932.
In 1932 Cushing wrote “ There is to day nothing in the whole realm of surgery more gratifying than the successful removal of a meningioma with subsequent functional recovery.” Most of meningiomas are cured if completely removed.

The anatomical distribution of intracranial meningiomas is as approximately as follows:

Convexity   ( Frontal , Parietal , Occipital , Temporal )             Commonest

Parasagittal ( Anterior 1/3rd, Middle or posterior one third)                                                    

Falcine Meningioma (Anterior 1/3rd, Middle or posterior one third)
(arises from the falx,  completely concealed by overlying cortex, & initially does not involve the superior sagittal sinus but later may involve the sinus).
Falcine meningiomas can be divided into anterior, middle and posterior types. Anterior third extends from the crista galli to the coronal suture, the middle third from coronal suture to the lambdoid suture and posterior third from the lambdoid suture to the torcula.

Shenoid ridge or sphenoid wing meningioma ( Pterional, Alar or Clinoidal) 

Olfactory groove meningioma                         
Tuberculum sellae ( 5% to 10% of intracranial meningiomas)
                                                                                                                            
Intraventricular  ( 1% of all  meningomas, 90% are located at the trigone of lateral ventricle)   

Cavernous sinus meningioma

Meningioma of the optic nerve and orbit                                                                                                                            

Infratentorial  : Cerebellopontine angle , petroclival, jugular foramen, foramen magnum and basal meningiomas.
                              

                                                                                                                    
Pathology

Meningioma arises from arachnoid cap cells. The arachnoid villi protrude into the venpous sinuses. The venous endothelium is in contact with some arachnoid villi cells ( arachnoid cap cells ).
Meningioma is usually a slow growing, extraaxial and  well circumscribed tumor. 

Usually benign ( 32% of incidentally discovered meningiomas do not grow over 3 years follow up ).

Typically tumor has broad based attachment on dura  and  enchances densely.

Intratumoral  calcification is very common.
Classic histological finding is the presence of psammoma bodies.
Meningiomas are multiple in 8% of cases.

Occasionally meningioma forms a diffuse sheet of tumor over the dura and is known as meningioma en plaque.

 Histologically ( WHO classification 2007) meningioma  can be classified

GRADE 1

Meningothelial ( Syncytial) meningioma

Fibrous ( Fibroblastic) meningioma

Transitional ( Mixed) meningioma

Psammomatous meningioma

Angiomatous meningioma

Microcystic meningioma

Secretory meningioma

Lymphoplasmacyte- rich meningioma

Metaplastic meningioma



Meningiomas  with greater likelihood of recurrence and/or aggressive behavior  are WHO grade II & grade III meningiomas

GRADE II

Atypical  meningioma

Clear cell  meningioma

Chordoid  meningioma

GRADE III

Rhabdoid meningioma

Papillary  meningioma

Anaplastic ( Malignant ) meningioma


In year 2016, World Health Organization has published an updated version of classification of tumors of central nervous system. The new classification is both a conceptual and practical advance over its 2007 predecessor. For the first time , the WHO classification uses molecular parameters in addition to histology. So, the new classification is a combined genotype and phenotype classification.  But the classification and grading of meningiomas did not undergo revisions except for the introduction of brain invasion as a criterion for the diagnosis of atypical meningioma, WHO grade II.

So, the 2016 WHO classification of Meningiomas is as follows:


Meningioma

Meningothelial meningioma

Fibrous meningioma

Transitional meningioma

Psammomatous meningioma

Angiomatous meningioma

Microcystic meningioma

Secretory meningioma

Lymphoplasmacyte-rich meningioma

Metaplastic meningioma

Chordoid meningioma

Clear cell meningioma

Atypical meningioma

Papillary meningioma

Rhabdoid meningioma

Anaplastic ( malignant) meningioma
Radiological Features of Meningioma :

Plain radiography usually shows hyperostosis, increased vascular markings and calcification
CT scan : Meningioma is an extraaxial lesion [( there is no parenchyma all round the tumor, as on one side it is based over the dura ( bone)]. A well marginated ,  isodense to slightly hyperdense lesion,  homogenously and intensely enhancing , with associated brain edema  . Tumor is extraaxial lesion  with broad base against a bony structure or dural margin. The involved dura also enhances on contrast administration ( Dural tail sign).The bone adjacent to the dural base may show bony erosion or hyperostosis.
MRI brain with contrast and digital substraction angiography (DSA) are the other investigations for the operative planning for intracranial meningiomas.
MRI brain should always be done before the surgery as it provides better anatomical details and also gives a clue about the vascularity and type of meningioma.  It is indispensible in cases of CP angle tumor, Clinodial meningioma, etc.

Treatment goal : Complete Surgical Excision.
Sometimes it is not possible to completely excise the lesion due to its location. Under these conditions a subtotal resection should be done to aim for the complete functional recovery. As meningioma is relatively a benign lesion and remaining tumor takes long time to recur, the safe limit of resection may be done.

Simpson classification of extent of resection for intracranial meningima
Grade 1                Gross total resection of tumor, dural attachment and involved abnormal bone
Grade II                Gross total resection of tumor & coagulation of dural attachment
Grade III               Gross total ( Macroscopic ) resection of tumor
Grade IV               Subtotal ( Partial ) resection
Grade V                Simple decompression


References:
H.Richard Winn’s Youmans Neurological surgery, Schmidek & Sweet operative Neurosurgical techniques.
Greenberg M.S., Handbook of neurosurgery, 7th ed. Thieme
WHO classification of tumors of the central nervous system,2007 ( 4th ed)
WHO classification of tumor of central nervous system, 2016 update
Review article :  David N.Louis et al. The 2016 World health organization classification of tumors of the central nervous system: a summary. Acta Neuropathol ( 2016) , 131: 803-820.




                                    

Friday 2 August 2013

Neuro-oncology: Brain Tumors

About a century back Harvey Cushing published the work on brain tumors. The current World Health Organization Classification of the Central Nervous System , fourth edition (WHO 2007), lists more than 120 types of brain tumors. This is broadly a histopathological classification.
How to understand about brain tumors?  We are very much familier with the nomenclature used in the older classifications . A comprehensive WHO classification of CNS tumors helps in understanding the characterstics of the brain tumors . So, while describing these tumors, for a better understading,  older terms in conjuction with newer terms should be used.
GLIOMA is the commonest primary brain tumor. Glioma arises from glial cells. Since glial cells are far more in number than neuronal cells, it will be easy to understand the fact that gliomas are more common. Glial cells comprise of astrocytes, oligodendrocytes, ependymal cells so the gliomas can further be subclassified as astrocytoma ( commonest type of glioma ), oligodendroglioma and ependymoma. According to WHO classification, these tumors can further be subclassified on the basis of features of malignancy ( microvascular proliferation, cellular atypia, mitotic activity , necrosis ) from grade I, II, III and IV.
AS neuronal cells are less in number than glial cells it is easy to remember that tumors like NEURONAL  & MIXED NEURONAL GLIAL TUMORS are less common , and relatively benign tumors . Gangliocytoma ( WHO grade I ) and ganglioglioma ( WHO grade I or III ) are well differentiated tumors composed of neoplastc mature appearing neurons alone ( gangliocytoma) or neoplastic ganglion cells combined with glioma cells ( ganglioglioma). Dysplastc gangliocytoma of the cerebellum ( Lhermitte-Duclos disease, WHO grade I ) is associated with Cowden syndrome in 50 % cases. Central Neurocytoma & extraventricular neurocytoma ( WHO grade II ) are low grade neoplasms of young adults. Paraganglioma of the filum terminale ( WHO grade I ), Papillary glioneuronal tumor ( WHO grade I ) are surgically curable tumors. Dysembryoplastic neuroepithelial tumors ( DNT; WHO grade I ) is a low grade quasihamartomatous tumor that occurs in childrenand young patients with history of long standing resistant seizures.
Astrocytomas
Can be classified as circumscribed and diffuse type.
Circumscribed Astrocytoma can further be subdivided
Pilocytic astrocytoma ( WHO Grade I ) : grow very slowly, common in children and young adults, preferentially affects the cerebellum, brainstem, optic nerves and third ventricular region.
Subependymal giant cell astrocytoma ( WHO grade I ): intraventricular , associated with tuberous sclerosis.
Desmoplastic infantile astrocytoma: rare tumor of infancy.
Pilomyxoid astrocytoma ( WHO grade II)
Pleomorphic Xanthoastrocytoma ( WHO grade II)
Diffuse astrocytoma ( WHO grade II)
Anaplastic Astrocytoma ( WHO grade III )
Glioblastoma multiforme ( GBM ) WHO grade IV , is the most common the most malignant primary brain tumor arising in adults. Microvascular proliferation, foci of necrosis are the histologic hallmarks of GBM. Pleomorphism, increased mitotic activity , positive immunostaining for GFAP ( Glial Fibrillary Acidic Protein ) are other features of GBM.
OLIGODENDRGLIOMA & OLIGOASTROCYTIC GLIAL TUMORS
Oligodendroglioma ( WHO grade II )
Anaplastic oligodendroglioma ( WHO grade III )
Mixed Diffuse gliomas with astrocytic and oligodendroglial components: Oligoastrocytoma ( WHO grade II ) and anaplastic oligoastrocytoma ( WHO grade III )
EPENDYMAL TUMORS
Myxopapillary ependymoma ( WHO grade I ): a distinct low grade variant of ependymoma that arises almost exclusively from the caudal portion of the spinal cord ( conus medullaris/ filum terminale ).
Subependymoma ( WHO grade I ) usually intraventricular
Ependymoma ( WHO grade II ) : originates from the ependymal lining of the cerebral ventricles, usually a slowly growing neoplasm of children and young adults.
Anaplastic ependymoma ( WHO grade III )





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