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