Abhidha Shah

Analysis of the anatomy of the Papez circuit and adjoining limbic system by fiber dissection techniques

Fiber dissection techniques were used to study the limbic system, in particular the Papez circuit. The course, length and anatomical relations of the structures that make up the Papez circuit were delineated. Ten previously frozen and formalin-fixed cadaveric human brains were used, and dissected according to the fiber dissection techniques of Klingler et al. (Schweiz Arch Neurol Psychiatry 1935;36:247-56). The primary dissection tools were thin and curved wooden and metallic spatulas with tips of varying sizes. We found that the Papez circuit (mean length: 350 mm) begins in the hippocampus and continues into the fornix to reach the mamillary body. From there, the mamillothalamic tract continues to the anterior nucleus of the thalamus, which in turn connects to the cingulum by means of anterior thalamic radiations (mean length: 30 mm). The cingulum courses around the corpus callosum to end in the entorhinal cortex, which then projects to the hippocampus, thus completing the circuit. The average length and breadth of the mamillothalamic tract was 18 mm and 1.73 mm respectively. The average length of the cingulum was 19.6 cm and that of the fornix was 71 mm. The entire circuit was anatomically dissected first in situ in the hemisphere and was then reconstructed outside after removing its various components using fine fiber dissection under a surgical microscope. We found that fiber dissection elegantly delineates the anatomical subtleties of the Papez circuit and provides a three-dimensional perspective of the limbic system. Intricate knowledge of the anatomy of this part of the brain aids the neurosurgeon while performing epilepsy surgery and while approaching intrinsic brain parenchymal, ventricular and paraventricular lesions.

Atlantoaxial joint distraction as a treatment for basilar invagination: A report of an experience with 11 cases

OBJECTIVEnA novel method of treatment of basilar invagination that involves distraction of the atlantoaxial joint using specially designed spiked spacers is described. Bone graft that is additionally placed within the appropriately prepared atlantoaxial joint and posterior to the arch of atlas and lamina of C2 provides bony fusion.nnnMATERIALS AND METHODSnBetween December 2002 and April 2007, 11 patients underwent the discussed method of fixation at the Department of Neurosurgery, King Edward Memorial Hospital in Mumbai, India. All 11 patients had congenital basilar invagination and the symptoms were progressive in nature.nnnRESULTSnThe mean follow-up period was 21 months (range 8-40 months). Neurological improvement and successful distraction with atlantoaxial stabilization and ultimate bone fusion was achieved in all the patients and was documented with dynamic radiography. There were no neurological, vascular, or infective complications.nnnCONCLUSIONSnWe conclude that the described method of atlantoaxial joint distraction and fixation provides an alternative treatment strategy for cases with basilar invagination. Joint distraction as a stand-alone method could provide reduction of basilar invagination and firm stabilization in such cases.

Lateral supracerebellar transtentorial approach to a middle fossa epidermoid tumor

A 40-year-old patient was admitted with a 9-month history of headaches and multiple episodes of generalized seizures. Investigations revealed a medial temporal epidermoid tumor that extended into the suprasellar region. The tumor was surgically resected using a lateral supracerebellar-transtentorial approach. The rationale for the surgical approach and its validity in this clinical situation is discussed.

Atlantoaxial manual realignment in a patient with traumatic atlantoaxial joint disruption

We report a patient with complex traumatic translatory atlantoaxial dislocation, who we treated by joint exposure and reduction of the dislocation by facet manipulation and subsequent plate and screw atlantoaxial fixation. A 28-year-old male had fallen 7.6m (25 feet), and following the fall had severe neck pain but no neurological deficit. Investigations revealed a fracture at the base of the odontoid process and posterior displacement of the entire atlas over the axis, resulting in a translatory atlantoaxial dislocation. Head traction failed as he developed severe vertigo following its application. The patient was operated upon in a prone position. We opened the atlantoaxial joint and realigned the facets using distraction and manipulation techniques and secured the joint using a plate and screw interarticular method. The patient tolerated the treatment well and was symptom-free after 28 months. Postoperative images showed good craniovertebral alignment. Although technically challenging, direct manipulation of the facets of the atlas and axis can result in excellent craniovertebral realignment.

Lateral atlantoaxial facetal dislocation in craniovertebral region tuberculosis: report of a case and analysis of an alternative treatment

PurposeA case of tuberculosis is reported in which there was extensive unilateral destruction of the bones of the craniovertebral junction. A lateral facetal subluxation of the relatively well-preserved contralateral atlantoaxial joint was identified. The patient was treated with unilateral fixation of the subluxated joint using a lateral mass plate and screw method of fixation. The pathogenesis of facetal subluxation and the rationale of the treatment adopted are discussed.Case reportA 63-year-old male patient had systemic tuberculosis and had been on drug treatment for 5 months. For about 1 month, he had experienced severe neck pain and progressive quadriparesis. Investigations revealed extensive unilateral destruction of the lateral masses of atlas and axis and occipital condyle. MRI showed altered cord signal at the level of the craniovertebral junction. CT scan showed contralateral lateral subluxation of the facet of atlas over the facet of axis. Unilateral fixation and distraction of the lateral mass of atlas and axis, external orthosis and antituberculous drug treatment resulted in rapid and sustained neurological recovery.ConclusionContralateral atlantoaxial facetal subluxation can be a result of osteoligamentous incompetence in cases of tuberculosis where there is unilateral facetal destruction. A coronal CT scan view can be diagnostic in such cases. Atlantoaxial lateral mass fixation can be a rational form of surgical treatment in such cases.

Bifid Anterior and Posterior Arches of Atlas: Surgical Implication and Analysis of 70 Cases.

BACKGROUNDnOn reviewing the database of patients with craniovertebral junction anomalies, the authors identified 70 patients with a bifid posterior arch of atlas.nnnOBJECTIVEnTo speculate on the pathogenesis of spondyloschisis of both the anterior and posterior arches of atlas, particularly as it relates to atlantoaxial instability.nnnMETHODSnSeventy patients with bifid anterior and posterior arches were identified by a retrospective review of the database from 2007 to 2013.nnnRESULTSnThe ages of the patients ranged from 14 months to 50 years. The patients were divided into 3 groups. Group 1 (3 patients) had multiple additional spinal bony and neural abnormalities. Group 2 (34 patients) had mobile and partially (5) or completely (29) reducible atlantoaxial dislocation. Group 3 (33 patients) had atlantoaxial instability and related basilar invagination. The os odontoideum was identified in 21 patients, and C2-3 fusion was seen in 24 patients. Two of 3 patients in group 1 were treated conservatively and without any surgery. All patients in groups 2 and 3 were surgically treated. Surgery was done using lateral mass plate/rod and screw fixation techniques. The general observation during surgery included identification of discrete movements of both halves of the atlas, lateral positioning of the facets of atlas in relation to the facets of the axis and occipital condyle and closer approximation of the occipital bone, atlas, and axis resulting in crumpling of bone and neural elements.nnnCONCLUSIONnUnderstanding of the pathogenesis and mechanical alterations in cases with a bifid arch of atlas can assist in evaluating the clinical implications and in conduct of surgery.

“Interdural” oculomotor neurinoma: report of two surgically treated cases

BackgroundDural relationships and their possible implications on surgical treatment of oculomotor nerve neurinomas are discussed on the basis of surgical experience with two cases.Materials and methodsWe describe two cases with large oculomotor neurinomas that probably arose from the precavernous sinus segment of the nerve. Both tumors were located entirely within the confines of dura or were “interdural.” Operating within the limits set and protection afforded by the dura, the tumors could be excised relatively easily and safely. While the third nerve function recovered completely in one patient, the other continued to have complete third nerve palsy. The duration of follow-up in two cases was 52 and 24xa0months.Results and conclusionsEven the intracranial component of large oculomotor neurinoma can be covered entirely by dura. Understanding of the dural relationship can assist in planning and conduct of surgery.

Unusual bone formation in the anterior rim of foramen magnum: cause, effect and treatment

A rare case of proatlas segmental abnormality resulting in a bony mass in the anterior rim of the foramen magnum is studied. Case report of a 19-year-old female showed a progressive weakness of all four limbs for about 3 years. When admitted she could not perform any useful activities by herself. Investigations revealed an unusual bone growth in the region of the anterior rim of foramen magnum that resulted in severe cord compression. The abnormal bone formation involved the lower end of clivus, the tip of the odontoid process and the posterior arch of the atlas. Dynamic imaging did not reveal any clear evidence of instability. Following transoral decompression and posterior fixation, the patient showed dramatic and lasting clinical recovery. Conclusions were drawn as follows. Anomalies of the most caudal part of the occipital sclerotomes due to the failure of proatlas segmentation can be the cause of an abnormal bone mass in the anterior rim of foramen magnum. Transoral decompression, followed by posterior atlantoaxial fixation, results in neurological recovery and provides lasting cure from the problem.

Bilateral vasculopexy of anomalous vertebral arteries causing cervicomedullary compression: case report and technical note

AbstractIntroductionThe authors report an extremely rare cause of cervicomedullary cord compression by anomalous ectatic vertebral arteries.Material A 50-year-old male patient presented with a 9 month history of progressive quadriparesis. Investigations revealed that the vertebral arteries on both sides had a mirror-like course and caused a deep indentation into the high cervical cord. Bilateral vasculopexy was done using Teflon slings. The treatment resulted in rapid recovery from symptoms. Conclusionsn Anomalous course of the vertebral artery can result in symptoms of high cervical cord compression. Vasculopexy can result in lasting cure from symptoms.

Spontaneous tension pneumocephalus in a patient with subdural empyema

We report a 45-year old male who developed subdural empyema (SE) with tension pneumocephalus. The patient was admitted unconscious with tonic extensor response to pain. A gas-forming organism, Escherichia coli, was detected. Surgical evacuation of the pus and treatment with the appropriate antibiotic did not result in amelioration of his symptoms and the patient died. We identified a rare clinical situation when the SE cavity had a relatively large air loculus that was clearly related to gas-forming bacteria. It appeared that the patient had developed tension pneumocephalus related to the air produced by the pathogen. To our knowledge, this is the first report of a gas-forming organism in an abscess cavity that resulted in tension pneumocephalus and related symptoms.