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Journal of the Anatomical Society of India

An Aproach For Removal Of Brain, Brain Stem With Spinal Cord Needed For Study Of Anatomy And Autopsy

Author(s): Tridib Kr. Sett, Pranab Mukherjee, Swapan Bhattacharya, L.K. Vaid

Vol. 56, No. 1 (2007-01 - 2007-06)

Tridib Kr. Sett, Pranab Mukherjee, Swapan Bhattacharya, L. K. Vaid

R. G. Kar Medical College,Kolkata

Abastract:

Removal of vault of skull, squamous part of occipital bone and posterior arch of atlas is accomplished. Following this, bilateral laminectomy of vertebrae helps viewing of brain, posterior part of brain stem, spinal cord, all the spinal nerve roots and cauda equina. The first and second cranial nerves and nerve roots from the brain stem and spinal cord are cut carefully, some of the small venous sinuses are also sacrificed in the process. This modified approach helps total removal of brain, brain stem and spinal cord with its coverings with large venous sinuses remaining intact. Total twenty (20) cadavers are disseceted within a span of two years in two different medical colleges of West Bengal of India with good results.

Key words: Removal of Brain, Removal of Spinal cord.

Introduction:

The procedure adopted, so long, for removal of brain entails circumferencial cut across the skull, (beginning with removal of scalp enmasse and then a saw cut around the bare skull bones). The procedure not infrequently results in some of the nerve roots being severed with inevitable damage to the brain stem and more importantly a clear exposure of the posterior fossa is not possible – an obvious limitation of the conventional procedure. In view of the above, a new approach albeit an alternative approach for removal of brain with or without spinal cord has been contemplated and this is being practised in this department with good results.

Materials and Methods:

Cadavers numbering twenty (20), only those with sound physical signs of good embalming were selected for this study. The cadavers were dissected in a span of two (2) years. The work started in North Bengal Medical College, Darjeeling, West Bengal and carried forward in R. G. Kar Medical College, Kolkata, West Bengal.

Instruments used for this dissection were scalpel, toothed and untoothed forceps, scissors (straight and curved), chisel (curved and straight), hammer, hand-saw, bone nibbler, bone cutter, L-retractor, and electric saw, and periostenm elevator.

The approach followed in this study is really a combination of the classical approaches for removal of brain and spinal cord (Brash J. C 1958) with an addition involving the removal of he remains of the squamous part of the occipital bone, left over after the removal of skullcap by a circumferential cut and posterior laminectomy of all vertebrae (Canale S. T. – 1998).

The cadavers selected were laid in supine position on the dissection table before starting the dissection. The head was cleanly shaved. With a skin pencil a circular mark was drawn (anteriorly 2 cm above the mergins of the orbit, laterally above the auricle and posteriorly 1 cm above the occiput). The scalp enmasse is freed from the skull cap by a sharp long bladed knife along the marked line. The avulsed scalp is made to hang by a pedicle at the root of the nose. Next a circular saw cut is given across the skull, keeping the cutting edge of the saw always on the top of the skin edge surrounding the lower part of the head, this obviously makes the cut in line with the pencil mark over the head. Thus a little more than vault of skull is removed leaving the endosteal layer of dura and venous sinuses with the brain.

In the next step of removal of the brain with meninges by lifting the basal aspect of the frontal lobe, root-lets of olfactory nerves are cut. Thereafter optic nerve is approached after separating the dural attachments from the posterior margin of lesser wing of sphenoid bone. The optic nerves are cut closed to their exit from the optic canals and this necessitates lifting the frontal lobe somewhat and tearing of the stalk of pituitary gland. Next the third and fourth cranial nerves are dealt with and these are cut at their points of entry into the cavernous sinus. After that the most important part of removal of brain is cutting of tentorium cerebelli along the superior border of the petrous part of temporal bone. This exposes the cerebellum, which conceals the ventrally lying Pons and Medulla oblongata.

On continuous traction of inferior surface of brain 5th, 6th, 7th and 8th cranial nerves are identified and cut. After identification of lower four cranial nerves they are carefully dissected out and it is the difficult part of dissection. In the next step, the cadaver is turned prone, the remaing scalp is cleaned, two oblique incisions like a flower vas are given from the cut margin of squamous part of the occipital bone extending upto posterior arch of atlas. Posterior nuchal muscles are turned down and removed, then squmous part of occipital bone is nibbled and removed in piece meal. Posterior aspect of the brain with meninges is clearly exposed. Parallel vertical (centering the spines) skin incisions are continued down upto the coccyx (Fig -1).

Skin, subcutaneous tissue, deepfascia, and erector spinae group of extensor muscles are removed. Bilateral laminectomy is carefully done with a bone nibbler. Supra spinous and inter spinous ligaments are cut during the process. This exposes the spinal cord within the meninges with the roots of upper spinal nerves proceerding to their respective intervertebral foramina and caudally the cauda equina (Fig – 2). The roots of all the spinal nerves including those of the cauda equina are cut which freed the brain and spinal cord (within the meaninges) enabling their removal . The specimen, so obtained, is used for academic purpose or kept in museum.

Fig. 1 Removal of vault of skull, occipital bone

Removal of vault of skull, occipital bone

Fig. 2 Visualization of brain and spinal cord with caudaequina laminectomy of all vertebrae with its meninges and nerve roots coming out.

Visualization of brain and spinal cord

Fig. 3 Intact brain, spinal cord, caudaequina with its meninges and nerve roots coming out.

ntact brain, spinal cord, caudaequina

Discussion:

In the classical removal (Brash J. C. -1958) brain is severed from the spinal cord by a cut through the lower part of medulla. In the newer approach the intact removal of entire brain, the spinal cord, the meninges, the nerve roots, along with the cauda equina is accomplished with some extra efforts. (Canale S. T. 1998). Triangles of neck can be left for routine dissections. This methodof dissection holds out a great promise for viewing the spinal cord within its meninges as it lies within the vertebral canal (Woodburne R. T. , Burkle W. E. – 1994) and the whole brain plus spinal cord thus removed, may be kept as a good museum specimen (Fig -3) and also can be used for teaching. Moreover posterior laminectomy undertaken in this method is the basic operative procedure for spinal decompressive neurosurgery (Hoppenfield S, Pietde Boer – 1999), (Rob C. , Smith R. -1979). This will help the orthopaedic and neurosurgery students. For forensic study (Knight Bernared -1996) collection of blood haematoma is easily seen whether it is subdural or extradural and spinal cord injury and fault of operation (medico-legal) can be assesed.

Space occupying leisons in brain, brain stem, spinal cord and canal are better observed (for autopsy study). Embalmed body is better studied than non-embalmed nonetheless in non-embalmed body this method can also be persued. In forensic autopsy instead of two incisions one cenral incision can be given and after removal of brain and spinal cord (if required) skin is sutured easily.

Referrences:

  1. Brash JC: Cunningham’s Manual of Practical Anatomy. 12th Edn; Vol-III. Oxford University Press, London; 1961, Pp 88 – 124.
  2. Canale ST: Campbell’s Operative Orthopaedics. In: “The Spine”,Chapter – 55; 9th Edn; Vol III. Mosby; 1998, pp – 2681-85, 2696-2702.
  3. Hoppenfield S, deBore P: Surgical exposures in Orthopaedics, The Anatomic approach. In: “The Spine,” Chapter – VI; 2nd Edn; Lippincott Raven, Philadelphia; 1999, pp 216-25, 246-69, 274-278, 287-292.
  4. Knight B: Forensic Pathology in The Forensic Autopsy. 2nd Edn; Arnold (Hodder Headline Group), London. 1996, Pp 20-24.
  5. Rob C, Smith R: Operative Surgery Fundamental International Technique of Neurosurgery. In: (i) Posterior approaches to Cervical Disc; (ii) Thoracic Laminectomy for Tumour surgery; (iii) Laminectomy of the Lumbar Spine; 3rd Edn; Butterworth. 1979, Pp – 438, 472, 484.
  6. Woodburn RT, Burkel WE: Essentials of Human anatomy. In: “Back;” 9th Edn; Oxford University Press, London. 1994, Pp 335-56.
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