Arterial spin labeling hyperperfusion in Rasmussen's encephalitis: Is it due to focal brain inflammation or a postictal phenomenon?

BACKGROUND AND PURPOSE

The study evaluated the utility of arterial spin labeling (ASL) perfusion imaging in Rasmussen's encephalitis (RE).

MATERIAL AND METHODS

The hospital electronic database was searched using the search words "encephalitis," "autoimmune encephalitis" and "Rasmussen's encephalitis" for the period of 1 Jan 2015 to 31 Jan 2017. Clinically diagnosed cases of RE for which epilepsy protocol magnetic resonance imaging (MRI) with perfusion imaging (ASL) performed on a 3T scanner were retrieved. The diagnosis of RE was based on Bien's criteria (Bien et al., 2005). We obtained patient's demographic details, clinical features, electrophysiological studies, and follow-up data from electronic hospital records.

RESULTS

We included nine patients with RE of whom seven patients showed increased perfusion, and two patients decreased perfusion. Among these patients, MRI changes of gyral hyperintensity without volume loss corresponded to regional ASL hyperperfusion in six patients and ASL hypoperfusion in one patient. Two patients who showed ASL hypoperfusion had corresponding atrophy on MRI. Eight patients of RE had epilepsia partialis continua (EPC) or daily seizures, and one patient was seizure-free post-surgery. Five patients showed a concordance of ASL hyperperfusion with clinical ictal onset zone. Among the seven patients with ASL hyperperfusion, the finding was concordant (complete or partial) with the electroencephalogram (EEG) ictal onset zone in six patients and with interictal epileptiform discharges (IED) in seven patients.

CONCLUSION

Increased perfusion in ASL of the involved brain parenchyma in RE is a common MRI finding and may be due to either active inflammation of the brain involved or a seizure-related finding.

Is 'burned-out hippocampus' syndrome a distinct electro-clinical variant of MTLE-HS syndrome?

AIM

To study the clinical, electrophysiological and imaging characteristics of patients with unilateral mesial temporal lobe epilepsy (MTLE) with contralateral ictal onset on scalp EEG, viz. 'burned-out hippocampus' syndrome (MTLE-BHS).

METHODS

MTLE-BHS was defined as TLE with unilateral hippocampal sclerosis (HS) without any dual pathology on MRI and contralateral ictal onset on scalp EEG, unlike in classical hippocampal sclerosis (HS). Consecutive "MTLE-BHS" patients evaluated at our Centre for Comprehensive Epilepsy Care from January 2005 to July 2014 were studied. Twenty-five cases of classic MTLE-HS operated during the same period were also analyzed for comparison.

RESULTS

Seventeen patients were diagnosed to have MTLE-BHS. Mean age of seizure onset was 9.5±7.7years and the mean duration of epilepsy was18.2±7.3years. Epigastric aura was more common in MTLE-HS and fear, secondary generalized seizures and temporal polar changes on MRI were more prevalent in the MTLE-BHS subgroup. In the latter group, five (29%) exhibited seizure semiology and 2 (12%) had interictal discharges discordant to the side of MTS. Eight (47%) patients in the MTLE-BHS sub-group had normal medial temporal volume on Scheltens scale. Eight patients among MTLE-BHS underwent surgery (4 following intracranial monitoring that localized to the side of HS) with Engel class I outcome at 1year follow-up in 6 and Engel class II outcome in 2.

CONCLUSION

Attenuation of ipsilateral fast ictal rhythms on scalp EEG as well as neocortical changes are likely to be deterministic factors for MTLE-BHS as opposed to the severity of hippocampal atrophy. Considering good post-operative outcomes, intracranial monitoring for surgical selection is not mandatory in MTLE-BHS despite discordant semiology and ictal onset, in the presence of inter-ictal, functional imaging and neuropsychology data concordant to the side of HS.

Epilepsy with myoclonic absences: Electroclinical characteristics in a distinctive pediatric epilepsy phenotype

PURPOSE

The purpose of this article was to study the electroclinical characteristics and seizure outcome of children with epilepsy with myoclonic absences (EMA).

METHOD

In this descriptive cohort study, we reviewed clinical records of patients who met the criteria for EMA. Each patient's demographic data, birth/developmental history, seizure semiology/pattern, antiepileptic drugs (AED), clinical examination, video-electroencephalography (VEEG), and neuroimaging data were reviewed. Response to AED and change in seizure frequency/pattern on follow-up were noted. Responders were defined by seizure freedom/>50% reduction in seizure frequency on follow-up.

RESULT

Twelve children were diagnosed with EMA between 2008 and 2013 [50% male; mean age of onset: 3.5years]. Main seizure types were the characteristic myoclonic absences (100%) and generalized tonic-clonic seizures (42%). Ictal correlate on VEEG was 3- to 3.5-Hz spike-and-wave discharges (82%) and fast recruiting bifrontal rhythm (25%). One patient had specific MRI abnormalities. Mean duration of follow-up was 23.9months. Seizure frequency had significantly improved on follow-up (p=0.005), and at last follow-up, nine patients were in the responder group: four seizure-free for at least 1year, two with >90%, and three with >50% reduction in seizure frequency. The number of AED reduced significantly between initial visit and last follow-up among responders. Two patients on follow-up developed different seizure patterns, with generalized tonic and complex partial seizures. One responder expired because of unprovoked generalized convulsive status epilepticus.

CONCLUSION

This cohort, the largest from the Indian subcontinent on the rare syndrome of EMA, suggests mild heterogeneity in a seemingly homogenous electroclinical phenotype. Clinical semiology while unique may demonstrate focality and variable ictal patterns. Most patients respond to either valproate monotherapy or valproate-lamotrigine combination; however, the prognosis remains guarded. The seizures of a minority of patients remain drug-refractory and may evolve into tonic or complex partial seizures.

A critical evaluation of the lateralizing significance of material-specific memory deficits in patients with mesial temporal lobe epilepsy with hippocampal sclerosis

To critically assess the value of material-specific memory deficits in lateralizing temporal lobe dysfunction preoperatively, we compared the neuropsychological data of 50 consecutive patients with unilateral mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS; right: 31, left: 19) with those of 50 age- and education-matched healthy control subjects. On case-control comparison, both the subcohorts with left and right MTLE-HS performed poorly on intelligence tests, in addition to individual memory tests. However, comparison of the verbal and visual memory functions between subcohorts with right and left MTLE-HS revealed that learning trials and delayed word list recall were the only tests that hypothesized left temporal lobe dysfunction. We conclude that material-specific memory deficits are largely test driven, but there is a lateralizing role for task-specific deficits in left MTLE-HS. Although neuropsychological data help to define baseline neuropsychological impairment, caution should be exercised in interpreting the lateralizing value of material-specific memory deficits prior to surgery.

Atonic variant of benign childhood epilepsy with centrotemporal spikes (atonic-BECTS): a distinct electro-clinical syndrome

PURPOSE

To describe the clinical and electroencephalographic features, treatment strategies and outcome in a series of children with the atonic variant of benign childhood epilepsy with centrotemporal spikes (atonic-BECTS).

MATERIAL AND METHODS

Out of the 148 patients with BECTS reviewed from January 2005 to June 2010 in our Institute, there were seven (5%) with atonic-BECTS. All underwent video EEG, high-resolution magnetic resonance imaging (MRI), neuropsychological evaluation and language assessment. Their progress was followed. In addition to sodium valproate, three were treated with steroids, followed by intravenous immunoglobulin (IVIG) when the seizures relapsed while tapering or after stopping the steroids.

RESULTS

All of the children had earlier onset (mean=2.4 years), increased frequency and increased duration of focal seizures compared to typical BECTS. Head drop and truncal sway due to axial or axiorhizomelic atonia occurring several times per day or week was the key manifestation. The atonic seizures worsened with carbamazepine in three, clonazepam in two and clobazam in one. When the atypical seizures commenced, some children developed one or more of the following problems: hyperactivity, attention deficit, clumsy gait, and mild cognitive or language dysfunction. Three children became seizure free, one on steroids and the other two on IVIG.

CONCLUSIONS

BECTS in children with an early age of onset and frequent and prolonged seizures is more likely to evolve into atonic-BECTS. Carbamazepine and some benzodiazepines may worsen these seizures. Three children became seizure free with immunomodulatory therapy, one on steroids and the other two on IVIG, and had complete resolution of the transient motor and cognitive impairment. Atonic-BECTS needs to be differentiated from Lennox-Gastaut syndrome since it is potentially treatable and children recover with no sequel. Although all the children in this series continued to be on treatment with sodium valproate it is currently undetermined whether they would have required to do so if followed up for an extended period of time.

Post-irradiation "acquired cavernous angiomas" with drug resistant seizures

Cavernomas are well-known congenital vascular lesions with presumably high epileptogenicity. We report two patients who developed cavernomas; both were in remission from childhood acute lymphoblastic leukemia following standard chemo-radiotherapy. They developed drug-resistant focal epilepsy secondary to cavernomas and were subjected to surgical/medical management. This report highlights the ictogenesis of radiation-induced "acquired" cavernous angiomatosis in the brain. Appropriate treatment, including resection of these lesions in selected cases, improves the quality of life in such patients.

An unusual cause of adult onset cerebellar ataxia with hypogonadism

We report an unusual case of sporadic adult onset cerebellar ataxia with hypogonadism. A 40-year-old unmarried man presented with progressive ataxia and dysarthria along with complaints of non-development of secondary sexual characteristics and erectile dysfunction. There were complaints of intermittent diarrhea. Clinical examination revealed a pan-cerebellar syndrome with features of hypoandrogenism. No eye movement abnormalities were evident. There were signs of malabsorption. Investigations confirmed the presence of auto-antibodies found in celiac disease, and a duodenal biopsy confirmed the same. Hypoandrogenism was postulated to be due to hypergonadotropic hypogonadism which has been mentioned in a few patients of celiac disease. However, the pattern seen in our patient was of a hypogonadotropic hypogonadism. This is probably secondary to an autoimmune hypophysitis seen in some patients in the absence of other clinical manifestations. Autoantibody testing should be a diagnostic necessity in any adult with a sporadic cerebellar ataxia.