Shubhabrata Biswas

Accuracy of four-dimensional CT angiography in detection and characterisation of arteriovenous malformations and dural arteriovenous fistulas.

A retrospective review was made to assess the accuracy of four dimensional CT angiogram (4D-CTA) in diagnosis of arteriovenous malformations (AVM) and dural arteriovenous fistulas (DAVF), with catheter-based digital-subtraction angiogram (DSA) being gold standard. 33 pairs of investigations (DSA and 4D-CTA) were performed primarily for suspicion of AVM/DAVF. Based on blinded reports, sensitivity and specificity for detection of AVM/DAVF were 77% (95% CI: 46 - 95%) and 100% (95% CI: 83 - 100%) respectively. Positive predictive value was 100% (95% CI: 69 - 100%) and negative predictive value 87% (95% CI: 66-97%). 4D-CTA is a practical minimally-invasive technique for evaluating cerebrovascular pathologies. There is good agreement between the findings of 4D-CTA and DSA despite the differences in temporal and spatial resolutions. 4D-CTA may obviate the need for DSA in a subgroup of patients who would otherwise have undergone this invasive investigation, which carries a risk of important complications.

Novel use of 4D-CTA in imaging of intranidal aneurysms in an acutely ruptured arteriovenous malformation: is this the way forward?

Ruptured arteriovenous malformation (AVM) is a frequent cause of intracranial hemorrhage. The presence of associated aneurysms, especially intranidal aneurysms, is considered to increase the risk of re-hemorrhage. We present two cases where an intranidal aneurysm was demonstrated on four-dimensional CT angiography (time-resolved CT angiography) (4D-CTA). These features were confirmed by digital subtraction angiography (catheter arterial angiogram). This is the first report of an intranidal aneurysm demonstrated by 4D-CTA. 4D-CTA can offer a comprehensive evaluation of the angioarchitecture and flow dynamics of an AVM for appropriate classification and management.

Cerebral CT Venography Using a 320-MDCT Scanner With a Time-Density Curve Technique and Low Volume of Contrast Agent: Comparison With Fixed Time-Delay Technique

OBJECTIVE The purpose of this study was to compare a cerebral CT venography (CTV) technique performed on a 320-MDCT scanner with the use of a time-density curve (TDC) and a small volume of IV contrast medium (35 mL, with 15 mL used for the test bolus) with CTV performed using an established reference technique in which scanning is performed at a fixed time delay of 30 seconds with the use of a larger volume of contrast medium (100 mL). MATERIALS AND METHODS The time of peak enhancement was determined from the TDC generated from a scan in which a test bolus dose was used. CTV was performed at the time of peak enhancement. The diagnostic quality of 31 CTV venograms acquired using this technique was compared retrospectively with the diagnostic quality of 29 CTV venograms obtained at a fixed time delay of 30 seconds. The densities in the major venous sinuses and the degree of arterial contamination on the scans acquired using the two techniques were compared using objective and semiobjective methods. The semiobjective assessments were made independently by two neuroradiologists. RESULTS Attenuation was higher in the venous structures seen on CTV images acquired using the TDC technique. Of the scans obtained using the TDC technique, the proportion deemed to be of good quality, on the basis of a grading scale, was statistically significantly higher (p < 0.05). Also, the degree of arterial contamination was statistically significantly lower (p < 0.05). The interrater agreement for semiobjective assessments ranged from good to very good. CONCLUSION We describe a CTV technique performed using a low volume of IV contrast medium and a TDC on a 320-MDCT scanner. This technique provides better venous opacification and lower arterial contamination compared with use of the fixed time-delay technique.

Serial imaging and management of ganglioglioma with unusual presentation and meningeal spread

Dear Editor, We report the case of a 28-year-old female with migrainous headaches and refractory epilepsy from a ganglioglioma with leptomeningeal extension treated with serial imaging, stepwise medical management, and surgical resection. Gangliogliomas are rare intra-axial tumors (around 1% of cranial CNS neoplasms) of mixed neuronal and glial origin that most commonly occur in the temporal lobes and present with refractory epilepsy predominantly in children and young adults [3, 7]. She described 20 months of a constant left fronto-temporal headache with daily throbbing exacerbations, aggravated by movement, sound, and light. She had no neurological deficits and an ECOG (Eastern Cooperative Oncology Group) score of 1. Her past medical history included depression. Her family history included brain tumors, depression, breast and cervical cancer, but no epilepsy. She developed intermittent diplopia without any obvious ocular cause, 6 weeks of weight loss, and reduced appetite. Moderate pleocytosis on CSF analysis suggested chronic inflammation. MR imaging showed left hippocampal head expansion with T2 hyperintensity and T1 hypointensity. The left postero-lateral midbrain, superior left cerebellar hemisphere cortex and the vermis with its adjacent white matter on the right showed T2 hyperintensity. Contrast demonstrated a homogenously enhancing ovoid lesion arising from the left hippocampal head, extending into the left lateral ventricle temporal horn. Florid thick dural and leptomeningeal enhancement along the left cerebellar convexity, right side of the vermis, left temporal lobe convexity, postero-lateral midbrain, and anterior pons (with enhancement along the left trigeminal nerve) was present. Certain areas suggested intraaxial extension. Enhancing nodules were identified at the right lateral ventricle anterior pole and along the right side of the anterior falx. Figure 1 shows representative images. Her gallium scan was normal. Biopsy in December 2009 was compatible with a low-grade glioma, and possibly a ganglioglioma. Her MRI in July 2010 was unchanged. Biopsy of the meningeal enhancement to exclude a second pathology was considered too hazardous given her symptoms. Despite reporting worsening memory in March 2011, neuropsychological assessment found her cognitive functioning to be average or better in all domains tested, but identified signs of severe anxiety and moderate depression. Nearly 2 years post presentation, partial and generalized tonic clonic seizures developed. Lamotrigine was commenced in May 2012, increasing to 50 mg BD. After MR imaging demonstrated lesion growth, it was excised in October 2012. The histology showed a biphasic tumor composed of ganglioid cells demonstrating a large amphophilic cytoplasm containing vesicular nuclei with prominent nucleoli and * Andrew Dapaah andrewdapaah@silver-rain.com

The long-term outcomes of epilepsy surgery

Objective Despite modern anti-epileptic drug treatment, approximately 30% of epilepsies remain medically refractory and for these patients, epilepsy surgery may be a treatment option. There have been numerous studies demonstrating good outcome of epilepsy surgery in the short to median term however, there are a limited number of studies looking at the long-term outcomes. The aim of this study was to ascertain the long-term outcome of resective epilepsy surgery in a large neurosurgery hospital in the U.K. Methods This a retrospective analysis of prospectively collected data. We used the 2001 International League Against Epilepsy (ILAE) classification system to classify seizure freedom and Kaplan-Meier survival analysis to estimate the probability of seizure freedom. Results We included 284 patients who underwent epilepsy surgery (178 anterior temporal lobe resections, 37 selective amygdalohippocampectomies, 33 temporal lesionectomies, 36 extratemporal lesionectomies), and had a prospective median follow-up of 5 years (range 1–27). Kaplan-Meier estimates showed that 47% (95% CI 40–58) remained seizure free (apart from simple partial seizures) at 5 years and 38% (95% CI 31–45) at 10 years after surgery. 74% (95% CI 69–80) had a greater than 50% seizure reduction at 5 years and 70% (95% CI 64–77) at 10 years. Patients who had an amygdalohippocampectomy were more likely to have seizure recurrence than patients who had an anterior temporal lobe resection (p = 0.006) and temporal lesionectomy (p = 0.029). There was no significant difference between extra temporal and temporal lesionectomies. Hippocampal sclerosis was associated with a good outcome but declined in relative frequency over the years. Conclusion The vast majority of patients who were not seizure free experienced at least a substantial and long-lasting reduction in seizure frequency. A positive long-term outcome after epilepsy surgery is possible for many patients and especially those with hippocampal sclerosis or those who had anterior temporal lobe resections.

1724 Mri-analysis in patients with ‘non-lesional’ epilepsy

Patients with focal epilepsy presenting without lesions often do not respond to medical treatment and are less likely to receive resective surgery. The objective was to improve lesion detection and conspicuousness using a dedicated epilepsy research MRI protocol at a specialist surgical centre. We studied 40 controls and 43 patients with epilepsy who were deemed to be MRI-negative by virtue of earlier non-specialist MRI assessment. Localization of seizure onset had been evaluated using seizure semiology and EEG. We re-evaluated these patient cases with our protocol using (i) diagnostic assessment of multiple MRI sequences by an experienced neuroradiologist and (ii) an automated quantitative voxel-based lesion detection technique where T1-weighted image-based feature maps were entered into separate t-tests between individual patients and controls (uncorrected p<0.01 and p<0.05 FWE-cluster-corrected). 27 patients remained MRI-negative after investigation by a neuroradiologist. 16 patients (37%) had at least one potentially epileptogenic lesion (including focal cortical dysplasia and hippocampal sclerosis), 11 had lesions concordant with the likely epileptogenic region identified by EEG. Both feature maps together detected all sites of dysplasia (100%). A dedicated epilepsy research protocol can increase identification of patients with lesions by up to 37%. Diagnostics can be complemented by sensitive automated statistical testing.

PO037 The drop of glue that fixed my mind

Intracranial dural arteriovenous fistula is a rare cause of reversible vascular dementia, through a presumed mechanism of intracerebral venous hypertension. The clinical presentations are variable with no easily recognisable syndrome. It is a treatable and reversible cause of cognitive decline, unexplained otherwise. Often the sole presentation could be progressive cognitive decline to suggest a neurodegenerative dementia however the careful clinical history may give the clue of increasing intracranial pressure. Careful radiological review will help to intervene early to cure this condition. We report a case of 55 year old man who presented with progressive symptoms of pulsatile tinnitus for two years, with features of encephalopathy for six month and subsequent focal neurological symptoms and seizure. He was initially diagnosed as dementia and was later treated as stroke before he was referred to our centre. MRI scan of brain revealed dilated veins along the cerebral convexities and the brain stem with progressive diffuse white matter oedema. Cerebral angiography revealed a dural A-V fistula around the right transverse/sigmoid sinus. His history of familial hemochromatosis raises the suspicion of hyperviscosity induced venous thrombus as the putative cause. This was treated with onyx embolisation. His symptoms and the radiological abnormalities resolved completely.

Recurrent life-threatening haemoptysis from a bleeding vertebral artery pseudoaneurysm: A diagnostic dilemma

A bleeding vertebral artery pseudoaneurysm is a rare cause of haemoptysis. Pseudoaneurysm can arise due to radionecrosis from previous radiotherapy in the base of skull and neck region and may present with haemoptysis many years later. It is important to be aware of this entity in the work-up of haemoptysis, particularly in patients with previous base of skull and neck radiotherapy. Our patient was successfully treated with endovascular occlusion.

Letter to the editor of Acta Neurochirurgica: transient splenial lesion in a pre-surgical epilepsy patient – a no-touch lesion

Dear Editor, We would like to report the finding of a transient splenial lesion in an epilepsy patient undergoing pre-surgical work-up for a lesion in the left parahippocampal gyrus. There is documentation in the literature of clinically silent lesions in the splenium of the corpus callosum in patients with epilepsy. The aetiology and pathogenesis is largely unknown [2, 7, 8]. These lesions usually do not cause neurological deficits and disappear after weeks to months. It is a recognized phenomenon within neuroradiology, recently abbreviated to RESLES (reversible splenial lesion syndrome) [2], however not widely in neurosurgical literature, particularly in the presence of another known presumed neoplastic lesion. A 19-year-old left-handed female student was discussed at the Epilepsy Surgery meeting. She had a 9-year history of drug-resistant, complex partial seizures. Seizure frequency was one to two stereotypical automatisms per week after she was changed to lamotrigine 200 mg BD. The patient has no additional significant history. On examination, she was GCS 15 with no focal neurology, and neuro-cognitive examinations were unremarkable. Her initial imaging in early 2010 showed a left posterior parahippocampal gyrus abnormality. Considering the clinical scenario and the radiological appearances, the likely differentials were a low-grade glioma or dysembryoplastic neuroepithelial tumour. Follow-up imaging showed no interval change of the left hippocampal lesion, but there was an ovoid area of increased signal (on T2W images) within the splenium of the corpus callosummeasuring 12mm by 7.5 mm axially (Fig. 1), which was not present on the previous studies. It demonstrated restricted diffusion and did not enhance. Functional MRI demonstrated left hemisphere language dominance with primary language centres distant from the left hippocampal lesion. Video telemetry in November 2012 captured two typical seizures associated with rhythmic slow activity over the left cerebral hemisphere. Her EEG in January 2013 was within normal limits. The patient’s routine blood results were all within normal range, and she did not exhibit any clinical signs of lamotrigine toxicity. As a result, no change was made to her medication, and repeat MRI imaging seven months later in March 2013 showed complete resolution of the corpus callosum lesion (Fig. 1). Clinically silent, transient lesions of the corpus callosum due to seizure activity, AED toxicity, and cerebral infections where AED treatment is not involved have been described in the literature [2, 9]. Differentials of such lesions based on imaging alone include ischaemia, posterior reversible encephalopathy syndrome, multiple sclerosis, Marchiafava–Bignami disease, diffuse axonal injury, and extrapontine myelinosis. Most AEDs have been implicated in the cause of these lesions [1, 3–8]. There does not seem to be a predilection for age, sex, AED treatment, or seizure type in causing these lesions. This suggests the possibility of different processes leading to one common causal pathway. The frequency of reversible splenial lesions in patients who undergo pre-op evaluation for epilepsy surgery lies at less than 1 % [5]. Polster et al., 2001 [7] suggested rapid AED change or even transient arginine-vasopressin imbalance due to AED withdrawal as possible etiologies. Gurtler et al., 2005 [3] compared 16 patients with a splenial lesion to 32 control patients and found no difference in the frequency of seizures N. Srikandarajah : J. O. Farah Department of Neurosurgery, The Walton Centre, Liverpool, UK