Coma and Glasgow Coma scale

Most of the non medical people use word coma to describe a patient who is unconscious. But for a medical professional word "coma" is very specific because the impairment of arousal can vary from drowsiness ( sleepiness) to non-responding to any stimulus like sound or pain. Coma is the severest impairment of arousal, and is defined as the inability to obey commands, speak, or open  the eyes to pain.

One should learn the GCS scale to better understand the different levels of impairment of conscious level and to avoid descrepencies in describing the daily condition of the patient by different medical professionals and nurses.
Teasdale and Jennet,  in year 1875,  proposed a scale known as GCS ( Glasgow Coma Scale). Three types of stimulus and response to the patient to these three stimuli is described.
First is EYE OPENING
If patient opens his eyes spontaneously , i.e., like a normal person without any problem , then 4 point is mentioned.
Next situation is that patient is drowsy or feeling sleepy and is having closed eyes. The sleepy patient if opens eyes on sound then 3 point is given.
If patient eyes are closed and he opens eyes only when painful stimulus is given the, only 2 points is given.
And patient does not open eyes even on a painful stimulus then only 1 point is given so the lowest score of eye opening is 1.

E  4   spontaneous eye opening
E  3   opening eyes to speech
E  2   opening eyes to pain
E  1   None


Then  patient's verbal response is examined ( V stands for verbal response)


 V   5         Person is oriented 
                 (aware about what is happening around, Person is oriented to place, person and time )
 
 V    4        Confused or disoriented  

 V    3       speaking inappropriate words 
                                      ( Not producing sentences )

 V    2       producing incomprehensible words 
                                       ( Not producing word i.e. only some sound is produced by the patient) 

 V    1      None ( No verbal output means patient is not speaking and even not producing any sound)


Patient's Motor response is assessed

M      6      Obeys
          (Best motor resonpse is  M6 when patients moves limbs themselves and obey the command to move hand and feet whenever asked to do so)

M     5    patient localizes pain 
           ( when patient is pinched he tries to remove your fingers) 

M    4    Withdraws to pain
            ( here when patient is pinched feels pain and tries to withdraw from the pain)

M    3    Flexion to pain ( decorticate)
             ( in medical terminology it is known as decorticate posture , i.e., posture seen in an animal when the central nervous system is cut just below the level of cerebral cortex. Like in an experient by Sherrington, father of modern neurophysiology, when the brain of a cat was cut just  above the midbrain or brain stem, animal,s upper limbs were flexed and lower limbs were extended. This abnormal posture is known as DECORTICATE POSTURE)

M    2   Extensor ( decerebrate )
               ( extensor response to a painful stimulus is a very bad neurological sign. When a patient is pinched his both upper and lower limbs are extended)

M    1  No response to the painful stimulus


The best responses of the patient are added . So, the maximum GCS score is 15 and minimum is 3.

 
Glasgow coma scale score of equal or less than 8 is a generally accepted operational definition of coma.
It can result from dysfunction of brain stem, diencephalon or lesions of both cerebral hemispheres.This may be due to neoplastic lesions, electrolyte imbalance, metablic or endocrine problems, vascular lesions, infections, trauma or nutritional reasons.

GCS is an important method of describing patient's neurological condition but blood pressure, pulse rate,  respiratory rate, response of the pupils of  eye to light, paralysis of the limbs are other important parts of the  complete neurological assessment.

Pilocytic Astrocytoma and Pilomyxoid Astrocytoma

Pilocytic astrocytoma  is a relatively circumscribed, slowly growing, and is  often cystic lesion.
It commonly occurs in in children and young adults.
It is histologically characterized by a biphasic pattern with varying proportions of compacted bipolar cells associated with Rosenthal fibers and loose -textured multipolar cells associated with microcysts and eosinophilic granular bodies.
Rosenthal fibers are intracytoplasmic  corkscrew-shaped, brightly eosinophilic, hyaline masses.
Pilocytic astrocytoma corresponds to WHO grade1. Pilocytic astrocytomas comprise approximately 5% of all gliomas. It is the most common glioma in children, in whom the majority ( 67%) arise in the cerebellum.
Preferred sites include the optic nerve, optic chiasma/ hypothalamus, thalamus and basal ganglia, cerebral hemispheres , cerebellum and brain stem.
Involvement of the subarachnoid space is a common finding in pilocytic astrocytoma. It is not indicative of aggressive or malignant behavior, nor does it pretend subarachnoid dissemination.
Pilocytic astrocytoma may also seed the neuraxis.
Pilocytic astrocytomas are remarkable in maintaining their WHO grade I status over years and even decades. Very rarely, especially when previously irradiated, a malignat transformation may occur.
As with other CNS lesions, the neurological sign and symptoms depend on the location and size of the tumor. similarly non localizing signs like macrocephaly, headache, endocrinopathy are also seen. Seizures are uncommon since the lesions infrequently involve the cerebral cortex. Visual loss, hypothalamic and pituitary dysfunction like obesity and diabetes insipidus may occur.
CT scan brain  with contrast or MRI brain with contrast with MR spectroscopy helps in preoperative provisional diagnosis of the lesion. The cysts may be either solitary and massive , the tumor being a mural nodule, or multiple, smaller and intratumoral.

Pilomyxoid Astrocytoma

A piloid neoplasm, closely related to pilocytic astrocytoma, that has a prominant mucoid matrix and angiocentric arrangement of monomorphous, bipolar tumor cells, without Rosenthal fibers  or eosinophilic granular bodies/ hyaline deposits. Pilomyxoid astrocytoma corresponds to
WHO Grade II neoplasm. It typically presents in very young age group , median 10 months.



 

Primary Central Nervous System Lymphoma ( PCNL)

Extranodal malignant lymphomas may arise in the CNS in the absence of lymphoma outside the nervous system at the time of diagnosis. it is different from secondary involovement of the nervous system in systemic lymphomas.
Primary CNS lymphomas ( PCNL) were first described by Bailey in 1929 as "perithelial sarcoma."
Primary CNS lymphoma constitutes about 3% of all brain tumors.
Most are large B-cell lymphomas , only 2% of T-cell origin.
PCNL affects all ages, with a peak incidence in immunocompetent subjects during the sixth and seventh decade of life.
In immunocompromised patients, the age at manifestation is lowest in individuals who have an inherited immunodeficiency ( 10 years ) , followed by transplant recipients ( 37 years ) and AIDS patients ( 39 years ).
Common location is the brain parenchyma surrounding the ventricular system, but any craniospinal structure can be involved. AIDS epidemic led to increase in the incidence of Lymphoma.  The  clinical manifestations are similar to other intracranial space occupying lesions of the brain and like other brain tumors CT scan and MRI with contrast and MR spectroscopy helps to diagnose these tumors.
Majority of patients present with focal neurological deficit. Some patients present with features of raised intracranial pressure like headache and vomiting. Few patients present with neuropsychiatric symptoms and seizures. Eye symptoms due to uveitis or vitreous lymphoma may occur in about 5 percent cases. Dementia may also be a symptom of cns lymphoma.
About 50% of transplantation associated primary cns lymphomas appear within a year after transplantation.
PCNSL occur as a single or multiple masses in in deep location in cerebral hemisphere or in the peri ventricular region. It may be diffuse or well demarcated. Diffuse infiltrative form may present as lymphomatous cerebri. Meningeal lymphoma may present as meningioma or meningitis.
On CT scan it is infiltrative lesion with indistinct margins and isodense or hyperdense with homogeneous enhancement with minimal surrounding edema or compressive effect.  Solitary lesion in majority of cases. Lesions are usually supratentorial and localized in the deep periventricular areas.
Clinical presentation is similar to any other space occupying lesion. Steroid , cerebral decongestants and antiepileptic medication are given and a tissue diagnosis is possible with open biopsy and stereotactic biopsy.

2016- World Health Organization (WHO) classification of CNS tumors has classified the Lymphomas of the central nervous system as follows:

Diffuse large B-cell lymphoma of the CNS

Immunodeficiency-associated CNS lymphoma

          AIDS-related diffuse large B-cell lymphoma

          EBV-positive diffuse large B-cell lymphoma, NOS

          Lymphomatoid granulomatosis

Intravascular large B-cell lymphoma

Low-grade B-cell lymphoma of the CNS

T-cell & NK/T cell-lymphoma of the CNS

Anaplastic large cell lymphoma , ALK-positive

Anaplastic large cell lymphoma , ALK-negative

MALT lymphoma of the dura

Source: WHO classification of CNS tumors, 4th Ed. 2007 and 2016 update