2. Introduction
It is used to determine the cause of diffuse or multifocal diseases producing
minimal mass effect when the specific diagnosis cannot be established by any
other means
Studies assessing the usefulness and risks of brain biopsy began in 1950(Queen
square study) and was initially focused on 3 main areas namely Paediatric
Neurodegenrative diseases,viral encephalitis and dementia.
With advent of modern techniques for confirming conditions,indications for
brain biopsies have reduced markedly.
3. Criterias for Brain Biopsy
1) No alternate procedure can provide the diagnosis
2) The information from biopsy will serve a useful purpose
5. Infections
Herpes simplex encephalitis
although the diagnosis can be made on clinical and radiological evidence there
are certain factors that favour a biopsy namely
Only patients with infections due to herpes simplex and varicella zoster would
benefit from acyclovir therapy
It fairly commonly detects superadded bacterial or fungal infections which
require an entirely different therapy
6. Acquired immune deficiency syndrome
CT and MRI is commonly unable to distinguish the various CNS manifestations of
AIDS(toxoplasmosis vs lymphoma vs progressive multifocal leukoencephalopathy)
Definitive diagnosis of certain Bacterial and Fungal infections
mucormycosis, aspergillosis, nocardiosis and rare cases of actinomycosis require
biopsy for confirmation and appropriate treatment.
Chronic inflammatory conditions like lyme neuroborreliosis
7. Vasculitides
May present with multifocal symptoms and normal laboratory studies
May not even be visible on MRI or CT studies and requires biopsy on clinical
suspicion .
It is recommended to take biopsy from temporal tip including area of
longitudinally arranged surface vessels
8. Paediatric Neurodegenerative Disease
Majority of the cases can be diagnosed with Radiological ,biochemical and
genetic studies.
Two condition that require biopsy for differentiation are- Canavan’s disease
and Alexander’s disease.
9. Canavans Disease
Characterised by psychomotor retardation, macrocephaly and spasticity .
MRI shows high intensity signals in T2 weighted images.
This is an autosomal recessive condition and definitive diagnosis is necessary
for counselling.
Brain biopsy specimen shows intramyelenic vacuolation in the subcortical
white matter and swollen astrocytes with abnormal mitochondria in deeper
layers of the cortex
10. Alexanders disease
Sporadic
Unknown etiology
Presents in infancy with psychomotor retardation ,progressive enlargement of
head and spasticity.
Biopsy demonstrates Rosenthal fibres in subpial ,perivascular and
subependymal locations
No available treatment
12. Incidental Biopsy
It is incidental sampling of tissue at time of other operation e.g removal of
brain tissue/meninges at time of evacuation of haematoma, resection of
neoplasm etc.
13. Team approach
Brain biopsy should be preceded by discussions among the individual
requesting the biopsy, performing the biopsy and the one examining the
biopsy specimen.
This will help determine the appropriate site of biopsy and chosing the best
microbiological,morphological and neurochemical studies.
When possible the biopsy should be performed during the normal working
hours when a full complement of qualified technical personnel are available
to initiate various lab studies
14. Surgical technique
The procedure must be planned and executed with the ususal attention to
anaesthetic technique, positioning , skin preparation and draping, surgical
technique and dressing
Pre-operative antibiotic and anticonvulsant medication should be given
Drugs that alter sensorium should be minimized post -operatively
15. Anaesthesia and Medication
General endotracheal anaesthesia is used most commonly, but if patient is co-
operative biopsies can be taken under light sedation and local anaesthesia
If Raised ICP is a factor, Mannitol and hyperventilation should be utilised
16. Operative Technique
For a temporal Lobe biopsy, Patient is positioned supine and GA is induced.
With doughnut pad under the head, the head is turned to the side at a level
above the heart and a towel roll is placed under the shoulder.
A small area of scalp is shaved and operative site prepared .
A 5 cm curvilinear incision is drawn 1 cm anterior to the external auditory
meatus which extends up to the zygoma and turns posteriorly above the ear
to approximately 1 cm above the pinna
The region is draped with paper drapes and a betadine impregnated adhesive
plastic sheet placed.
17. The propsed incision site is infiltrated with 0.5-1% lidocaine with 1:100000 epinephrine.
The incision is carried to the peri-osteum and the bone is cleared. Retraction is maintained with
the Weitlaner retractor. A burrhole is made. (In awake patients, power drills are unncesarily loud
and potentially frightening hence avoided). The Hole is enlarged to 2-2.5 cm with roungeurs .
The Dura is opened in a cruciate or curvilinear fashion. Using a no 11 blade, the brain is incised
in a square large enough to obtain sufficient material for all the studies needed, generally 1-1.5
cm on each side and 1.5 cm deep, and including grey and white matter and its sulcus.
The tissue is undermined with a dissector and lifted free with a cuffed foreceps. After
haemostasis is obtained, a routine closure is carried out.
18. Tissue for viral and other cultures should be immediately placed in sterile
containers to avoid contamination.
Stereotactic craniotomy may be indicated to improve localization and
minimize the site of opening
