Pediatric thalamic tumors in the MRI era: a Canadian perspective.

BACKGROUND: Thalamic gliomas are rare. The natural history is unpredictable, and the optimal management of these tumors in children is poorly defined. The aim was to identify outcomes, prognostic factors, and response to various modalities of treatment in a relatively large population of pediatric thalamic tumors from many centers within a fairly homogeneous health care system. METHODS: We performed a Canadian multicenter retrospective review of pediatric thalamic tumors presenting during the MRI era (1989-2012). Radiology and pathology were reviewed by central independent reviewers. Paraffin shavings for RNA extraction were taken and tested for fusion events involving KIAA1549:BRAF. Tumors were classified as unilateral or bithalamic based on their origin on imaging. Univariate and multivariate analyses on factors influencing survival were performed. RESULTS: Seventy-two thalamic tumors were identified from 11 institutions. Females represented 53% of the study population, and the mean age at presentation was 8.9 years. Sixty-two tumors were unilateral and 10 bithalamic. Unilateral tumors had a greater propensity to grow inferiorly towards the brainstem. These tumors were predominantly low grade in comparison to bithalamic tumors which were high-grade astrocytomas. The 5-year overall survival was 61 ± 13% for unithalamic tumors compared to 37 ± 32% for bithalamic tumors (p = 0.097). Multivariate analysis indicated tumor grade as the only significant prognostic factor for unithalamic tumors. Six unilateral tumors, all low grade, were BRAF fusion positive. CONCLUSION: Unilateral and bilateral thalamic tumors behave differently. Surgical resection is an appropriate treatment option in unilateral tumors, most of which are low grade, but outcome is not related to extent of resection (EOR). Bilateral thalamic tumors have a poorer prognosis, but the occasional patient does remarkably well. The efficacy of chemotherapy and radiotherapy has not been clearly demonstrated. Novel therapeutic approaches are required to improve the prognosis for malignant unilateral thalamic tumors and bilateral thalamic tumors.

Isolated Discitis in Melioidosis: An Unknown Presentation and a Microbiological Challenge.

Burkholderia pseudomallei causes Whitmore's disease or melioidosis which is endemic in many South Asian countries including India. This gram-negative bacterium is frequently found in the moist soil and agricultural workers get infected most commonly. Most of the infections are asymptomatic and have a wide spectrum of manifestations as in tuberculosis. Melioidosis of the spine manifests as spondylodiscitis with paravertebral and prevertebral abscess and presentation as discitis alone is not reported. We report the first case of melioidosis causing isolated discitis without any obvious bony involvement. It also highlights the need for preoperative suspicion of these rare manifestations even in seemingly innocuous disc disease presenting as back pain and radiculopathy.

Surgical outcome in cystic vestibular schwannomas.

BACKGROUND: Cystic vestibular schwannomas (VS) form a rare subgroup that differs from the solid variant clinically, radiologically, and histopathologically. These tumors also vary in their surgical outcome and carry a different risk of post-operative complications. We analyzed our series of 64 patients with cystic VS and discuss the technical difficulties related to total excision of these tumors and focus on complication avoidance. MATERIALS AND METHODS: A retrospective review of cystic VS surgically managed over a span of 11 years. The case records were evaluated to record the clinical symptoms and signs, imaging findings, surgical procedure, complications, and follow-up data. Post-operative facial nerve palsy was analyzed with respect to tumor size and tumor type. RESULTS: Progressive hearing impairment was the most common initial symptom (76.6%). Atypical initial symptoms were present in 15 patients (23.4%). Preoperatively, 78% patients had good facial nerve function (HB grade 1, 2) and 22% had intermediate (HB grade 3, 4) to poor (HB grade 5 and 6) function. Mean tumor size was 4.1 cm. Complete tumor removal was achieved in 53 patients (83%). The facial nerve was anatomically intact but thinned out after tumor excision in 38 patients (59.4%). Ninety percent patients had either intermediate or poor facial nerve function at follow-up. Poor facial nerve outcome was associated with giant tumors and peripherally located, thin-walled cystic tumors. CONCLUSION: Resection of cystic VS is complicated by peritumoral adhesions of the capsule to the nerve. Extensive manipulation of the nerve in order to dissect the tumor-nerve barrier results in worse facial nerve outcome. The outcome is worse in peripherally located, thin-walled cystic VS as compared to centrally located, thick-walled cystic tumors. Subtotal excision may be justified, especially in tumors with dense adhesion of the cyst wall to the facial nerve in order to preserve nerve integrity.

The "vagal ansa": a source of complication in vagus nerve stimulation.

A 16-year-old boy underwent vagus nerve stimulation for treatment-resistant multifocal epilepsy. During intraoperative system diagnostics, vigorous contraction of the ipsilateral sternomastoid muscle was observed. On re-exploration, a thin nerve fiber passing from the vagus to the sternomastoid was found hooked up in the upper electrode. Detailed inspection revealed an abnormal course of the superior root of the ansa cervicalis, which descended down as a single nerve trunk with the vagus and separated to join the inferior root. The authors discuss the variation in the course of the ansa cervicalis and how this could be a reason for postoperative neck muscle contractions.

Long term outcome in surgically treated posterior fossa epidermoids.

OBJECTIVES: To study posterior fossa epidermoids treated surgically at our institute and to compare their long term outcome with respect to extent of surgical decompression. MATERIALS AND METHODS: Retrospective analysis of 50 cases of posterior fossa epidermoid surgically treated at our institute between 1997 and 2007. RESULTS: The mean duration from onset of symptoms to surgery was 2.5 years. Patients with cerebellopontine angle (CPA) epidermoids presented predominantly with trigeminal neuralgia (35%) and hearing loss (29%) while patients with fourth ventricle epidermoids had features of raised intracranial pressure (ICP) and gait ataxia (69.2% each). The rate of recurrence was 9% in tumors considered totally removed and 93% in those subtotally removed. Of the 17 patients with recurrences, 3 (7.9%) underwent a second operation. The mean duration of follow up at first recurrence was 9.3 years. CONCLUSION: Based on our experience, the rate of recurrence is significantly higher after subtotal removal as compared to total removal of epidermoids on long-term follow up. Symptomatic recurrence requiring re-exploration is evident only after a long duration (∼10.9 year) following primary surgery. Hence, total removal without producing new neurological deficits should be the standard goal when operating on posterior fossa epidermoid cysts.

Case Report: Floating fat globule within an arachnoid cyst.

Intralesional floating fat globules have been reported in cystic lesions such as teratoma of the ovary and dermoid of the head and neck but not within intracranial lesions. Fat globules dispersed within the subarachnoid space are a known imaging finding of ruptured intracranial dermoid. We report a unique case of an intralesional solitary floating fat globule within a multicompartmental arachnoid cyst, with varying locations on serial imaging. We also put forward a hypothesis for the pathogenesis of fat within an arachnoid cyst. To the best of our knowledge, this is the first such report in the literature.

Posterior reversible encephalopathy syndrome in a case of postoperative spinal extradural haematoma: case report and review of literature.

A 14-year-old girl presented with progressive paraparesis and paresthesia of one-year duration. Magnetic resonance imaging revealed a T6 vertebral hemangioma with epidural compression on the spinal cord. Following angiography and embolization, she underwent dorsal laminectomy and excision of the soft tissue component compressing the cord. In the postoperative period she had rapid worsening of lower limb power and imaging demonstrated an epidural haematoma at the operative site. The patient was taken up for urgent re-exploration and evacuation of haematoma. Postoperatively the patient complained of visual failure, headache and had multiple episodes of seizures. An magnetic resonance imaging brain showed characteristic features of posterior reversible encephalopathy syndrome (PRES) and the patient improved gradually after control of hypertension. This is the first documented case of PRES following spinal cord compression in a patient without any known risk factors. We postulate the possible mechanism involved in its pathogenesis.