Pros and Cons of C2 Nerve Sectioning/Preservation in Posterior Fusion for Congenital Atlantoaxial Dislocation.

OBJECTIVE: Deliberate C2 nerve root sectioning and its preservation have been described during posterior fusion for atlantoaxial dislocation (AAD). However, the associated outcomes have been less studied, especially in congenital AAD. Our objective was to study the clinical outcomes after C2 nerve root sectioning and the feasibility of C2 preservation in these patients. METHODS: The data from 190 patients were retrospectively studied. The decision to cut or preserve the C2 nerve root was determined by the preoperative radiologic findings and intraoperative suitability of its preservation. During follow-up, the patients were questioned about C2 nerve-related dysfunction. The pros and cons of sectioning or preservation of the C2 nerve root and the related feasibility factors are also described. RESULTS: Complex C1-C2 anatomy that required extensive dissection and drilling was seen in 139 patients. After C2 nerve root sectioning in 178 patients, none reported bothersome hypoesthesia, paresthesia, or dysesthesia that required medication. However, 9 patients (5.1%) developed nonhealing occipital ulcers and most required flap coverage or a skin graft. C2 nerve root preservation is feasible with an adequate inferior C1 lateral mass and normal-size ganglion. In patients with C1-occipital condyle hypoplasia, extremely oblique joints, spondyloptosis, incurved occiput, pseudofacets, and anomalous vertebral artery, preservation of the C2 nerve root is difficult. CONCLUSIONS: The advantages of sectioning the C2 nerve root are many. However, a subset of patients is prone to morbid occipital neuropathic ulcers. After C2 nerve sectioning, one should be cautious of such complications. C2 nerve root preservation should be strongly considered for patients with favorable anatomy.

Bilateral posterior fossa and temporo-occipital extra-dural hematomas: A simple novel technique.

Posterior fossa extra-dural hematoma is rare and early diagnosis and management is associated with good outcome. Twenty four year male presented with somnolence and soft tissue swelling of occipital region following road traffic accident. CT scan revealed bilateral posterior fossa with bilateral temporo-occipital Extradural Hematoma (EDH) with mass effect. He was operated through a trifoliate incision and craniotomies leaving a strip of bone over the transverse and occipital sinus. The blood loss with such technique was minimal and the control of sinus tear was easier as the dura on either sides of the sinus can to tied to each other to hitch the sinus up to the bone thereby, providing a good tamponade. Early diagnosis of posterior fossa EDH and prompt surgical evacuation especially in patients with mass effect provide excellent recovery. However, the surgery may be associated with significant blood loss due to venous sinus injury increasing the morbidity and mortality. We have described a novel technique that minimizes the blood loss for patients with PFEDH straddling across the venous sinuses.

Osteoblastic meningioma with turtle shell: Different entity from calcified meningioma.

Bone formation within meningioma is secondary to metaplasia of the meningothelial cells into osteoblastic cells. This needs to be differentiated form the commonly seen calcification. We describe a rare case of osteobalstic meningioma in which bony trabeculae were seen within meningothelial cells.

Endoscope-assisted, minimally invasive evacuation of sub-acute/chronic epidural hematoma: Novelty or paradox of Theseus?

BACKGROUND: Sub-acute/chronic epidural hematoma (EDH) may present with nagging symptoms of headache, nausea, vomiting, lethargy, etc. We attempted to offer a minimally invasive, single burr hole, endoscope-assisted evacuation of EDHs instead of a conventional craniotomy. METHODS: Seven patients with sub-acute/chronic EDH (six supratentorial and one infratentorial) presented to us 3 to 7 days after low-velocity road traffic accidents with complaints of headache and lethargy. The EDH volumes measured between 20 to 50 ml, and the patients were operated on using a single burr hole made through a small incision. We used 0-, 30- and 70-degree, angulated, rigid, high-definition endoscopes to identify and evacuate the organized clots in the extradural space. Flexible catheters were used for suction and irrigation. After achieving hemostasis, the dura was hitched back to the burr hole site. The wound was closed over a negative suction drain. RESULTS: All patients had prompt recovery from symptoms. Postoperative CT scans showed complete or near complete evacuation of the hematomas. The hospital stay and analgesic requirements were minimal. There was no infective complication or conversion to conventional open surgery. The average time for surgery was 77.8 min, and average blood loss was 328.5 ml. CONCLUSION: Endoscope-assisted evacuation of sub-acute/chronic EDH is a novel concept, which offers quick relief from symptoms in a minimally invasive fashion and a cosmetically acceptable way. None of the standard principles of surgery are hampered. It avoids extensive dissection of the temporalis or sub-occipital muscles. However, achieving hemostasis can be difficult. Further study and better equipment will validate the procedure.

'Atlas shrugged': congenital lateral angular irreducible atlantoaxial dislocation: a case series of complex variant and its management.

PURPOSE: The commonly described congenital atlanto-axial dislocation and Basilar-Invagination is antero-posterior or rotational or vertical plane. However, congenital dislocation in lateral plane has received scant attention. The purpose of this manuscript is to describe this unusual entity and discuss its management. MATERIALS AND METHODS: The clinic-radiological feature of seven patients with congenital lateral angular AAD (CLAAAD) were studied and managed. The unilateral C1 facet had subluxed lateral to C2-3 complex. The C1 and C2 facets were drilled comprehensively and repositioned with distraction, placement of metallic spacers and facet manipulation after insertion of screws. The post operative outcome was studied. RESULTS: The presentation is usually with neck tilt (progressive in 3) and/or progressive spastic quadriparesis. The mean C1-2 tilt was 25.2°. C1 was bifid in six patients. C1 lateral mass was assimilated with occipital condyle on dislocated side in and the other side was normal (6 patients). The dislocated C1-2 joint was abnormally oblique as compared to contralateral side. The relationship of occiput and C1 was normal. Correction of dislocation and lateral tilt was achieved in all patients with subsequent correction of neck tilt and deficits. One patient required reoperation. CONCLUSIONS: The acute angulation of joint on one side and near normal on other side leads to differential vertical movement, further accentuated by splaying of bifid C1. The entity is seen in young patients and often present with neck tilt and spastic quadriparesis. Management requires reshaping the joints and facet manipulation. If the reshaping is inappropriate, the joint is likely to redislocate before fusion occurs.

'Pseudofacets' or 'supernumerary facets' in congenital atlanto-axial dislocation: boon or bane?

PURPOSE: Certain abnormal contact points, appearing like additional joints (pseudofacets) were observed between atlas and axis in a subset of patients with congenital atlantoaxial dislocation (CAAD). The origin, function and bearing on management of such pseudofacets remain largely undetermined. The object is to study 'pseudofacets'or 'accessory joints' in patients with CAAD and to analyze the possible genesis, role and bearing of these on surgery and fusion rates. MATERIALS AND METHODS: 35 patients with CAAD were analyzed. Reconstructed images of CT craniovertebral junction passing through these pseudo and true facets were studied. A novel method was devised to measure the faceto-isthmic angle of axis, both in patients with CAAD and normal subjects. Operative details and fusion rates were studied in patients with pseudofacets and compared with those without it. RESULTS: Eight out of 35 patients (6 Irreducible CAAD and 2 with RCAAD) had pseudofacets. These are seen posterior to the true facets and resemble partially formed joints. The C2 facet was acutely bent over its isthmus in these patients. The direction of these pseudofacets appeared to counter the abnormal mobility at C1-2 true facets. Intraoperatively, they posed a visual hindrance to reach up to true facets for placement of spacers and lateral mass screws, requiring extensive drilling. At the same time, they did help in distraction and increased the surface for fusion between C1 and C2 in cases where sublaminar wiring alone was used. Fusion rates were 100 % in patients with pseudofacets. CONCLUSIONS: Pseudofacets may be a result of genetic aberration and nature's mechanism to restrict abnormal C1-2 mobility in CAAD by imparting some stability. Their presence hinders the visualization making it difficult to reach upto the true facets, thus a bane. They may require extensive drilling when direct posterior approach is used, thereby disrupting the natural restrictive mechanism. However, the flattened surfaces provide an increased area for postoperative bony fusion between C1 and 2, making their presence a 'boon'.

Olfactory region schwannoma: Excision with preservation of olfaction.

Olfactory region schwannomas are rare, but when they occur, they commonly arise from the meningeal branches of the trigeminal nerve and may present without involvement of the olfaction. A 24 year old lady presented with hemifacial paraesthesias. Radiology revealed a large olfactory region enhancing lesion. She was operated through a transbasal with olfactory preserving approach. This manuscript highlights the importance of olfactory preservation in such lesions.

Ruptured venous aneurysm of cervicomedullary junction.

BACKGROUND: Ruptured venous aneurysm is often seen with arterio-venous malformation (AVM) or developmental venous anomaly (DVA). However, isolated venous aneurysm is unusual. CASE DESCRIPTION: We present a case of ruptured venous aneurysm that presented with subarachnoid hemorrhage (SAH) and intraventricular hemorrhage (IVH). Digital substraction angiography (DSA) revealed a saccular contrast filling pouch in the left lateral aspect of cervicomedullary junction (CMJ). Endovascular intervention was not a viable option. During surgery, a saccular pliable structure approx. 1.5 × 1 cm was found in the subarachnoid space that was clipped and excised. There were no arterial feeders, no evidence of surrounding AVM, and no dilated perimedullary vein. CONCLUSION: This is perhaps the first reported case of ruptured venous aneurysm (without associated AVM) of CMJ, which was successfully managed surgically. The possible etiologies remain an unnoticed head trauma or a congenital vessel wall abnormality. Surgically clipping and excision remains the treatment of choice for such lesion.

Operative nuances to safeguard anomalous vertebral artery without compromising the surgery for congenital atlantoaxial dislocation: untying a tough knot between vessel and bone.

OBJECT: Stabilization of the craniovertebral junction (CVJ) by using lateral masses requires extensive dissection. The vertebral artery (VA) is commonly anomalous in patients with congenital CVJ anomaly. Such a vessel is likely to be injured during dissection or screw placement. In this study the authors discuss the importance of preoperative evaluation and certain intraoperative steps that reduce the chances of injury to such vessels. METHODS: A 3D CT angiogram was obtained in 15 consecutive patients undergoing surgery for congenital atlantoaxial dislocation. The course of the VA and its relationship to the C1-2 facets was studied in these patients. The anomalous VA was exposed intraoperatively, facet surfaces were drilled in all, and the screws were placed according to the disposition of the vessel. RESULTS: A skeletal anomaly was found in all 10 patients who had an anomalous VA. Four types of variations were noted: 1) the first intersegmental artery in 5 patients (bilateral in 1); 2) fenestration of VA in 1 patient; 3) anomalous posterior inferior cerebellar artery crossing the C1-2 joint in 1 patient; and 4) medial loop of VA in 5 patients. The anomalous vessel was dissected and the facet surfaces were drilled in all. The C-1 lateral mass screw was placed under vision, taking care not to compromise the anomalous vessel, although occipital screws or sublaminar wires were used in the initial cases. A medial loop of the VA necessitated placement of transpedicular or C-2 lateral mass screws instead of pars interarticularis screws. The anomalous vessel was injured in none. CONCLUSIONS: Preoperative 3D CT angiography is a highly useful method of imaging the artery in patients with CVJ anomaly. It helps in identifying the anomalous VA or its branch and its relationship to the C1-2 facets. The normal side should be surgically treated and distracted first because this helps in opening the abnormal side, aiding in dissection. In the posterior approach the C-2 nerve root is always encountered before the anomalous vessel. The defined vascular anatomy helps in choosing the type of screw. The vessel should be mobilized so as to aid the drilling of facets and the placement of screws and spacers under vision, avoiding its injury (direct or indirect) or compression. With these steps, C1-2 (short segment) rigid fusion can be achieved despite the presence of anomalous VA.

Posterior bilateral supernumerary atlantoaxial facets: true or false joint?

STUDY DESIGN: Case report. OBJECTIVE: To describe a symptomatic patient with bilateral posterior accessory C1-C2 joints and their differences from the true synovial joints. SUMMARY OF BACKGROUND DATA: Accessory joints between C1-C2 are rarely described. Origin and functional importance of such joints is unknown. Moreover only gross anatomic features of such joints were discussed in the past. The emphasis here is to review the morphology of such joints and to differentiate it from normal synovial joints. METHODS: A 17-year-old male presented with progressive spastic ataxia precipitated by episodic transient quadriparesis secondary to trivial trauma. Radiology revealed bilateral posterior C1-C2 accessory joints compressing the cervicomedullary junction. Both C1-C2 posterior arches were removed, excising the accessory joints. Fusion was achieved using C1-C2 lateral mass screws and is doing well at follow-up. RESULTS: The surfaces of these joints were smooth. Histopatholgy showed opposing osseous surfaces with articular cartilage but no synovium or articular capsule. CONCLUSION: Accessory C1-C2 joints are possibly a result of genetic aberration giving rise to abnormality in segmentation of C1 sclerotome. These joints are dysmorphic and partially formed as evidenced by the absence of synovial membrane and capsule. The function of such joints remains questionable.

Ependymoma misdiagnosed as tuberculoma, misguided by overemphasis on MR spectroscopy in endemic area.

Ependymomas and tuberculomas are common paediatric posterior fossa lesions in developing countries and may be confused with each other due to some overlapping features. The distinction is important as the treatment for each is entirely different. We have described three young children in whom clinical-radiological features and the lipid peak seen on MR spectroscopy suggested the diagnosis of posterior fossa tuberculomas. All of them were started on empirical anti-tuberculosis therapy (ATT). Increase in size/no response to anti-tuberculosis therapy was disregarded as a paradoxical response. Finally, with clinical-radiological signs worsening, surgical excision was undertaken. Histopathology revealed ependymoma in all three children. This report highlights the overdiagnosis of tuberculosis in endemic areas due to biased clinical approach compounded by false positive investigations. Tissue diagnosis, though difficult by minimally invasive methods, should be sought before initiating ATT. The attempts to establish a tissue diagnosis should be continued even after starting empirical therapy, rather than waiting for the response.