Thoracic and Lumbar pedicle screw insertion

Thorasic Spine: As a general rule the starting point for insertion of Pedicle screws is the point " where the superior border of the transverse process converges with the lamina along the lateral border of the articular facet. this point is typically in line with or just medial to the pars.

Lumbar Spine: The starting point is at the junction of the lateral facet and the transverse process (arrow)- taken from Spine Surgery (ed: Benzel; p 1056)
The other way is "Bisection of a vertical line through the facet joints and a horizontal line through the transverse process can also serve as a useful landmark for lumbar pedicle entry site".

Signs and Symptoms of Facet joint syndrome

The signs of Facet joint syndrome are

1. Local paraspinal tenderness;
2. Pain on hyperextension, rotation, and lateral bending;
3. Absence of neurologic deficit;
4. Absence of root tension sign; and hip, buttock, or back pain with straight leg raising .

Symptoms include

1. Hip and buttock pain,
2. Cramping leg pain involving the thigh but not radiating below the knee,
3. Low back stiffness, The back stiffness is typically most marked in the morning and
4. Absence of paresthesias.

Bruns Nystagmus

Bruns nystagmus is an unusual type of bilateral nystagmus most commonly occurring in patients with cerebellopontine angle tumours.
It is caused by the combination of slow, large amplitude nystagmus (gaze paretic nystagmus) when looking towards the side of the lesion, and rapid, small amplitude nystagmus (vestibular nystagmus) when looking away from the side of the lesion.
It occurs in 11% of patients with vestibular schwannoma, and occurs mainly in patients with larger tumours (67% of patients with tumours over 3.5cm diameter).
It may be caused by the compression of both flocculi, the vestibular part of the cerebellum, and improvement in both the nystagmus and balance problems occur commonly after removal of the tumour.
Bruns nystagmus is named for Ludwig Bruns

Stabilization of Dorsal Spine

I had a difficult case to manage independently in the very early post M.Ch period in the recent past.
A case of a 40 year male with a history of fall from a height of 20 feet and having total paraplegia and absent bowel and bladder sensation.
I thought of stabilizing the spine as I can mobilize the patient early and prevent the complications so forth. My experience with with Stabilization of dorsal spine with D2 to D5 screws and rods is very minimal as I had not done a similar case individually earlier.
With good home work I started the case and I could manage to do it reasonably good and safe. I had difficulty in identifying the starting point of the Pedicle screws and the land marks were not clearly visble. But with a little wider exposure I could make out the starting points and rest all went good under fluoro guidence. I had some more difficulty in decompressing the canal when I was trying to remove the anterior compression. But could manage adequate decompression at the end.

Post operatively patient didn't show good improvement and remained Grade 0 all through with no bowel and bladder sensations. POst OP period was uneventful and patient was discharged in a stable state.

Current management of Lumbar stenosis with Low grade Spondylolisthesis

Earlier view regarding the management of spinal canal stenosis with low grade Spondylolisthesis was by doing a laminectomy and wait and watch for the progression of listhesis and intervene accordingly.

But the current ideas regarding this is changing and is presented as a necessity for simultaneous stabilization and laminectomy. "Lumbar spinal fusion plus laminectomy appears to be a better option than laminectomy alone in terms of quality of life for patients with degenerative grade I spondylolisthesis with lumbar spinal stenosis"*.


* Zoher Ghogawala, MD, director of the Wallace Clinical Trials Center at Greenwich Hospital in Greenwich, Connecticut, presented these results from a prospective, 5-center, randomized, controlled trial here at the 80th Annual Scientific Meeting of the American Association of Neurological Surgeons.

Ref:  http://www.medscape.com/viewarticle/762967?src=mpnews&spon=26

Key Burr hole

The Key burr hole which is commonly performed in Pterional craniotomy is called the "Golf Club Head".

Ref: Photo Atlas of Skull Base Dissection: Techniques and Operative Approaches by Masahiko Wanibuchi.

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.

Townes view

It is taken with the patient in the supine position and lying on his back with the chin often depressed into the neck. 

The X-ray camera is angled at 30 degrees towards the feet so that the rays enter the head at the level of the hair-line.

The result is clear image of the posterior portion of the skull including the foramen magnum.

A reversed Towne's view is obtained by taking the radiograph from the posterior with the patient lying face down.

The stuctures that are demonstrated in Town's view are

Details of occipital bone(1)

Lambdoid suture (2)

Outline of Foramen magnum (3)

Dorsum Sellae (4) (White shadow in the foramen magnum)

Occipital crest (5)

Some of the details of the temporal bone like petrous ridge are also identified (1)