SAFE ENTRY ZONES TO BRAINSTEM

Safe entry zones to brainstem - Rationale

Ø  The brain stem is densely composed of important neural structures such as nuclei and neural tracts.

Ø  Causes of morbidity following brainstem surgery-

o   Direct damage during removal of the lesion,

o   Selection of an entry route into the brain stem, and

o   The direction of brain stem retraction

Ø  In most cases, the optimal surgical route can be established by use of the 2-point method, in which an imaginary line drawn from the center of the lesion to the point nearest the surface of the brain defines the least disruptive approach † Where critical neural structures are sparse and no perforating arteries are present.

Safe entry zones to brainstem

Suprafacial triangle

„ MLF medially

„ VII nerve caudally

„ SCP & ICP laterally

†  The brain stem can be retracted either laterally or rostrally with relative safety.

Infrafacial triangle

„ MLF medially,

„ Striae medullares caudally,

„ Facial nerve laterally

The brain stem can be retracted only laterally.

Safe entry zones to brainstem Anterolateral aspect

Midbrain- Lateral mesencephalic sulcus

Pons- Peritrigeminal area

Medulla- Retro-olivary sulcus

A redo L4/L5 Discectomy

Yesterday I started a redo L4/L5 discectomy. I started the case strictly adherent to the principles of redo surgery.
Unfortunately I had dural tear with root herniation while exposing the left lateral bony margin of the previous laminectomy. Boss came for my rescue and helped in closing the defect. Finally we successfully completed the surgery however in this process I have learnt some important practical points in redo laminectomy and discectomies which can be added up to the universal principles of redo surgery for successful completion.

1. Don't go too lateral in the earlier part of dissection as it can damage the radicular branches entering the spinal canal
2. Always dissect sharply than with a monopolar till you identify dura at least at one point.( My dural injury was with monopolar dissection)
3. Initial aim is to expose dura in a virgin area and follow it up to the desired extent.
4. In recurrent cases, almost always, there will be adhesion between the dural sleeve and the extruded disc material and it is impossible to do discectomy without releasing these adhesions

Management of Status Epilepticus

The terminology of Super refractory Staus epilepticus was new to me.
Here is the Guideline for Staging and management of status epilepticus with time intervals

Most important principle in recurrent surgery

Always have exposure more than the previous exposure.
Definitely have the bony margins exposed. If needed extend the craniotomy or laminotomy.
Definitely have normal dura exposed above and below the level of previous dural exposure. Without following these principles it is not possible to have safe surgery.
These principles hold good for both brain and spine surgery.

A big thanks for all my well wishers

Yes, It's official now.
After a very stressful period of 3 year Neurosurgical training I have cleared the final M.Ch examination.
All the credit goes to my boss who took pains to teach me good neurosurgical practice.
I also thank the Assistant Professors in the department for encouraging me all these days.
I should acknowledge my family for the support given in these 3 years.

MCA Segments

The middle cerebral artery can be classified into 4 parts:

M1Segment : Called as Sphenoidal Segment, due to its origin and loose lateral tracking of the sphenoid bone. It is also called as the Horizontal Segment. Starts at the point of carotid bifurcation and ends at Limen Insulae.

M2 segment : Extending anteriorly on the insula, this segment in known as the Insular Segment. It is also known as the Sylvian segment. The MCA branches may bifurcate or sometimes trifurcate into trunks in this segment .

M3 segment : This segment is also called Opercular Segment and extends laterally exteriorly from the insula towards the cortex.

M4 Segment : Called Cortical Segment. These begin at the external to the Sylvian fissure and extend distally away on the cortex of the brain.