Madhivanan Karthigeyan

Radiologic Dilemma in an Extra-Axial Petroclival Lesion: Low Grade versus High Grade

BACKGROUND Radiologic differentiation between a low-grade and high-grade lesion is crucial when deciding extent of resection and prognostication. Occasionally, imaging features can be confusing between the 2 lesions. We report a case that presented such a radiologic dilemma. The lesion appeared benign and extra-axial on routine magnetic resonance imaging sequences. However, subtle clinical and imaging clues pointed to a high-grade lesion. CASE DESCRIPTION A 27-year-old woman presented with multiple cranial nerve palsies, gait ataxia, and features of increased intracranial pressure. Computed tomography and magnetic resonance imaging showed a petroclival extra-axial contrast-enhancing lesion with areas of chunky calcification. Although choline peak on spectroscopy raised suspicion of a high-grade lesion, the primary differential diagnosis included meningioma and schwannoma considering its characteristic imaging appearance. Postoperative histopathology showed the lesion to be giant cell glioblastoma. CONCLUSIONS Apart from reporting a rare variant of glioblastoma in an unusual location, this case highlights atypical imaging in a glioblastoma. Brainstem edema may be a subtle indicator of the infiltrative nature of a tumor. Magnetic resonance spectroscopy may be a useful adjunct in such circumstances.

'Changing colors' of third ventricular tumor in a young woman

A 28-year-old woman presented with generalized tonic– clonic seizures of 8 months duration. Gadolinium-enhanced MRI of brain revealed multiple, parenchymal ring enhancing lesions suggestive of neurocysticercosis. The suprasellar and third ventricular region was normal (Fig. 1A). She was started on anti-epileptics and albendazole. Six months later, she developed painless progressive visual loss with behavioral changes. A repeat MRI brain showed a new T1 hypointense, T2 iso-hyperintense, heterogenously enhancing lesion in the third ventricle which was not present in the earlier scan (Fig. 1B-F). In view of progressive visual loss, she was operated upon and gross total excision of tumor was achieved. Intra-operatively the lesionwas grayish-white, mildly vascular with variegated consistency. Postoperatively, her vision improved. Histopathological study showed mixed germ cell tumor (MGCT) which stained positive for placental alkaline phosphatase (PLAP), negative for α-fetoprotein (AFP) and β-human chorionic gonadotropin (β-HCG). Cerebrospinal fluid (CSF) cytology performed was negative for malignant cells. Serum AFP and β-HCG levels measured were normal. MRI screening of craniospinal axis showed no evidence of disseminated disease. The patient underwent adjuvant chemoradiotherapy (CRT) (36 Gy in 20 fractions with six cycles of three weekly Cisplatin-based chemotherapy). Post-treatment, she was followed up with periodic assessment of serum AFP and β-HCG levels along with brain imaging. About 5 months after CRT, serial serum AFP levels showed a rising trend. A new MRI of the brain revealed no recurrent lesion. However, in view of elevated AFP levels, she was planned for spinal MRI to rule out metastatic disease. In the meantime, she presented with low backache and rapidly progressive paraparesis. Gadoliniumenhanced MRI of spine demonstrated a mildly enhancing intradural extramedullary lesion at D12-L1 level with cord compression. Unfortunately she succumbed soon after initiation of radiotherapy.

Pediatric Central Neurocytoma: A Short Series With Literature Review.

Central neurocytomas are well-differentiated tumors of neuronal origin. These are relatively uncommon in the pediatric population. Anaplastic features reflected by brisk mitotic activity, microvascular proliferation, necrosis, and MIB-1 labeling index >2% or 3% have been proposed to indicate aggressive behavior. Because of its rarity, there is paucity of data regarding the histologic spectrum and outcome of central neurocytomas in children. With this short series, we describe our observations of the clinicopathologic characteristics and outcome of this tumor in children over a 5-year period.

Unusual presentation of hyperphagia after surgery for fourth ventricular ependymoma: Accessory satiety center or hypothalamic seedlings?

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Anomalous V3 Segment Aneurysm Associated with Congenital Atlantoaxial Dislocation: Case Report and Discussing the Challenges in Management

BACKGROUND An anomalous vertebral artery is not a deterrent for posterior C1-C2 joint manipulation and reduction of atlantoaxial dislocation (AAD). However, presence of an incidental aneurysm in the aberrant segment of artery with concurrent AAD adds to the surgical challenge. CASE DESCRIPTION A 30-year-old woman presented with neck pain and spastic quadriparesis. Her imaging revealed atlantoaxial dislocation and bony segmentation defects. Three-dimensional computed tomography angiography showed bilateral anomalous vertebral arteries (V3 segment) and an incidental aneurysm on the arterial segment that crossed the right C1-C2 joint posteriorly. Because the artery bearing the aneurysm was nondominant, it was ligated and successful C1-C2 posterior reduction and fusion could be performed. CONCLUSION The association of an incidental aneurysm with an anomalous vertebral artery in congenital AAD is unusual. The etiology could be an underlying collagen defect or repeated shearing trauma to the vessel wall due to C1-C2 instability. It would be less risky to proceed with endovascular embolization followed by occipitocervical fusion without opening the joints in case the aneurysm is present on the dominant aberrant V3 segment. Ventral decompression can be supplemented for irreducible AAD. On the contrary, if the aneurysm is present on the nondominant aberrant V3 segment, the C1-2 joint can be opened and manipulated following an initial endovascular treatment of the aneurysm. If the circumstances demand, the nondominant artery can be ligated and sacrificed, although there is a small risk of formation of stump aneurysm.

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.

‘Congenital anomalies of craniovertebral junction presenting after 50 years of age’: An oxymoron or An unusual variation?

OBJECTIVES Manifestation of congenital anomalies of cranio-vertebral junction (CVJ) in the later half of life is unusual and intriguing. Coexisting cervical spondylotic changes with multilevel compression, poorer bone quality as well as less smooth post-surgical recuperation make management of elderly Congenital Atlantoaxial Dislocation/ Basilar Invagination (CAAD/BI) challenging. The clinico-radiological presentation, pathogenesis and outcome are analysed here. PATIENTS AND METHODS Clinico-radiological data of 20 patients of CAAD/BI (with markers of congenital anomalies) presenting after 50 years of age, the challenges faced and outcomes after C1-C2 fusion have been analysed. RESULTS Three distinct groups were identified. Seven patients with Os-odontoideum had reducible AAD (Type I). Seven patients had assimilated C1, C2-3 fusion and deformed C1-2 joints with irreducible AAD/BI (Type II). In type III, 4 patients had similar segmentation defects but with compression at both cervico-medullary junction and subaxial spine, although clinical localisation pointed to the CVJ. Spastic quadriparesis was the commonest presentation. All underwent C1-2 fusion alone. There was significant improvement in 18, including those with compression at additional level. Bony fusion was documented in all patients followed up beyond one year. CONCLUSION Congenital CVJ anomalies may present in later half of life, though attempts at reasoning remain speculative. These patients improve after multiplanar realignment and C1-2 fusion. Careful clinico-radiological evaluation is required in those with additional subaxial compression. Bone quality in elderly is not a deterrent for instrumentation. Fusion eventually occurs in most.

Multiplanar realignment for unstable Hangman’s fracture with Posterior C2-3 fusion: A prospective series

OBJECTIVE There is lack of consensus on the preferred approach for unstable Hangmans fracture. The associated soft tissue injuries apart from apparent bony injury add to the complexity of dislocation and needs to be addressed. Here, we evaluated the clinico-radiological characteristics and outcome of patients managed by posterior C2-3 fusion. PATIENTS & METHODS Nine patients with unstable Hangmans fracture (type II and IIA) were prospectively studied. The displacement of fractured fragments and C2-3 dislocation was studied in multiple planes. C2 pars-pedicle screw was placed to bring fractured fragments together (lag effect), which was then fused with C3 lateral masses to achieve multiplanar realignment. Clinical outcome was assessed in terms of pain (VAS score) and neurological status after surgery. Patients clinico-radiological status was followed up at regular intervals. RESULTS Pain was the predominant symptom (VAS: 8.1 ± 1.1). Only one had neurological deficit (ASIA- D). Mean VAS score improved significantly in postoperative period (1.2 ± 1.6). About two-third (66.7%) had atypical Hangmans. In six, fractured segments were malaligned in multiple planes. Axial rotation, lateral translation and superior translation (over-riding) of fragments were seen in 4, 4 and 3 patients respectively. Two had adjacent level injuries. Reduction and realignment of fractured fragments as well as C2-3 in multiple planes could be achieved in all. Follow-up varied from 6 to 22 months (mean, 12.8 ± 5.7). Bony fusion was evident in 9 to 12 months. Three patients showed mild curvature change in subaxial spine. CONCLUSION The fractures fragments may be dislocated in axial (rotation and lateral translation) apart from antero-posterior plane. It is important to study the radiology in various planes. Posterior C2-3 fusion is an effective way to achieve good realignment of bony fragments in all planes. It also addresses the instability resulting from soft tissue injury.

Improvise, adapt and overcome-challenges in management of pediatric congenital atlantoaxial dislocation

OBJECTIVE Congenital atlanto-axial dislocation (CAAD) often manifests in younger age group. Softer bones, deformed joints and the concern of fusing multiple segments in growing age set apart this subset of patients from adults. Objectives of this manuscript are to discuss the challenges faced and subsequent solutions during multiplanar realignment and fusion (short segment) of C1-2 joints through a direct posterior approach in pediatric CAAD. PATIENTS & METHODS 56 pediatric patients with CAAD were operated through a direct posterior approach in the last 4 years. The joints were drilled and manipulated to achieve multiplanar realignment. C1-2 joints were fused (short segment). The pre and post operative clinical and radiological data was compared. RESULTS Atlanto-axial dislocation was irreducible in 35 and reducible in 21 patients. Forty-nine (87.5%) patients were partially or totally dependent. The joints in the irreducible groups were oblique and deformed. Nine patients had lateral angular dislocation, 3 had C1-2 spondyloptosis and 5 had significant vertical dislocation. Drilling and manipulation was feasible in all cases. The bones were soft and partly cartilaginous in the pediatric population. Techniques were modified to achieve optimal bony purchase subsequent to drilling the relatively small bones and prevent screw pull-outs during intraoperative manipulation for the problems we had faced in our initial cases. Despite the challenges in initial cases, realignment could be achieved in all. There was a significant improvement in follow up modified JOA score and 28 patients were independent at 4-month follow up. Two patients had partial redislocation at 4-month follow up. CONCLUSIONS Pediatric patients have deformed and oblique joints, thereby making complete spondyloptosis, severe vertical dislocation and lateral tilt common in this age group. Though pediatric bones are soft and small, it is possible to achieve multiplanar realignment by drilling and manipulation of C1-2 joints. The realignment and short segment C1-2 fusion in these patients has a good radiological and clinical outcome.

Synchronous solitary calvarial yolk sac tumor metastasis as the initial presentation of mediastinal germ cell tumor

IntroductionIn children, malignant tumors presenting as a calvarial mass that too as initial manifestation are unusual. Also, brain metastases per se are rare in pediatric solid tumors with an incidence of just 1.5%.Case descriptionWe present a child with calvarial metastasis which was the presenting symptom of an otherwise asymptomatic large malignant mediastinal germ cell tumor (GCT). The lesion was dural-based involving both calvaria as well as the underlying brain parenchyma. Despite such multicompartmental location, no obvious bony destruction was seen. A 12-year-old boy presented with progressively enlarging scalp swelling and features of raised intracranial pressure. The lesion was totally excised and calvarial defect reconstructed using titanium mesh. Though the preoperative chest computed tomography suggested teratoma, the histopathology of the cranial lesion was a yolk sac tumor (YST).ConclusionInitial manifestation of GCT as calvarial swelling, pure YST (with no other germ cell component), and the eccentric multicompartmental (dural based) location rather than usual midline GCTs is noteworthy. The report thus highlights an atypical presentation in GCT. Although uncommon, it is worthwhile to consider metastatic GCT as a differential among calvarial lesions.