Chong H. Wong

The topography and significance of extratemporal hypometabolism in refractory mesial temporal lobe epilepsy examined by FDG‐PET

Purpose:  This study aims to map the temporal and extratemporal 18‐fluorodeoxyglucose positron emission tomography (FDG‐PET)–defined hypometabolism in mesial temporal lobe epilepsy (MTLE). We hypothesize that quantitative analysis will reveal extensive extratemporal glucose hypometabolism (EH), that the EH is related to seizure propagation beyond the temporal lobe, hypometabolism restricted to one temporal lobe predicts a good outcome following surgery, and EH predicts a poor outcome.

Voxel-based morphometric magnetic resonance imaging (MRI) postprocessing in MRI-negative epilepsies.

In the presurgical workup of magnetic resonance imaging (MRI)‐negative (MRI− or “nonlesional”) pharmacoresistant focal epilepsy (PFE) patients, discovering a previously undetected lesion can drastically change the evaluation and likely improve surgical outcome. Our study utilizes a voxel‐based MRI postprocessing technique, implemented in a morphometric analysis program (MAP), to facilitate detection of subtle abnormalities in a consecutive cohort of MRI− surgical candidates.

Brain activation patterns of versive, hypermotor, and bilateral asymmetric tonic seizures

Purpose:  Patients who have seizure onset from different brain regions can produce seizures that appear clinically indistinguishable from one another. These clinically stereotypic manifestations reflect epileptic activation of specific networks. Several studies have shown that ictal perfusion single photon emission computed tomography (SPECT) can reveal propagated ictal activity. We hypothesize that the pattern of hyperperfusion may reflect neuronal networks that generated specific ictal symptomatology.

Neuroimaging characteristics of MRI‐negative orbitofrontal epilepsy with focus on voxel‐based morphometric MRI postprocessing

The orbitofrontal (OF) region is one of the least explored regions of the cerebral cortex. There are few studies on patients with electrophysiologically and surgically confirmed OF epilepsy and a negative magnetic resonance imaging (MRI) study. We aimed to examine the neuroimaging characteristics of MRI‐negative OF epilepsy with the focus on a voxel‐based morphometric MRI postprocessing technique.

The cognitive profile of occipital lobe epilepsy and the selective association of left temporal lobe hypometabolism with verbal memory impairment

We investigated the cognitive profile of structural occipital lobe epilepsy (OLE) and whether verbal memory impairment is selectively associated with left temporal lobe hypometabolism on [18F]‐fluorodeoxyglucose positron emission tomography (FDG‐PET). Nine patients with OLE, ages 8–29 years, completed presurgical neuropsychological assessment. Composite measures were calculated for intelligence quotient (IQ), speed, attention, verbal memory, nonverbal memory, and executive functioning. In addition, the Wisconsin Card Sorting Test (WCST) was used as a specific measure of frontal lobe functioning. Presurgical FDG‐PET was analyzed with statistical parametric mapping in 8 patients relative to 16 healthy volunteers. Mild impairments were evident for IQ, speed, attention, and executive functioning. Four patients demonstrated moderate or severe verbal memory impairment. Temporal lobe hypometabolism was found in seven of eight patients. Poorer verbal memory was associated with left temporal lobe hypometabolism (p = 0.002), which was stronger (p = 0.03 and p = 0.005, respectively) than the association of left temporal lobe hypometabolism with executive functioning or with performance on the WCST. OLE is associated with widespread cognitive comorbidity, suggesting cortical dysfunction beyond the occipital lobe. Verbal memory impairment is selectively associated with left temporal lobe hypometabolism in OLE, supporting a link between neuropsychological dysfunction and remote hypometabolism in focal epilepsy.

Relationship between preoperative hypometabolism and surgical outcome in neocortical epilepsy surgery

Purpose:  Fluorine‐18‐fluorodeoxyglucose–positron emission tomography (FDG‐PET) hypometabolism has been used to localize the epileptogenic zone. However, glucose hypometabolism remote to the ictal focus is common and its relationship to surgical outcome has not been considered in many studies. We investigated the relationship between surgical outcome and FDG‐PET hypometabolism topography in a large cohort of patients with neocortical epilepsy.

Late onset Rasmussen's encephalitis with triple pathology

Rasmussens encephalitis is a devastating illness characterized by intractable focal seizures due to chronic localised encephalitis. We report on a rare variant of delayed onset Rasmussens encephalitis with triple pathology. A 27-year-old male, who was initially diagnosed with seizures when he was 16 years old, presented with focal seizures that became refractory to multiple anticonvulsants. Multiple investigations, including subdural electrode monitoring, revealed foci of onset in the right frontotemporal region. The patient underwent right front-temporal lobectomy. Post-operatively, the seizures became more severe and he developed new epilepsia partialis continua. Treatment with intravenous immunoglobulin was unsuccessful. He subsequently underwent a right hemispherectomy that rendered him seizure free. The three pathologies identified were old ischemic changes, type II cortical dysplasia and stage II Rasmussens encephalitis.

The relationship between neuropsychological functioning and FDG-PET hypometabolism in intractable mesial temporal lobe epilepsy

We examined the relationship between baseline neuropsychological functioning and 18-fluorodeoxyglucose positron emission tomography (FDG-PET) in intractable mesial temporal lobe epilepsy (MTLE). We hypothesized relationships between dominant temporal lobe hypometabolism and verbal memory and between nondominant temporal lobe hypometabolism and nonverbal memory in line with the lateralized material-specific model of memory deficits in MTLE. We also hypothesized an association between performance on frontal lobe neuropsychological tests and prefrontal hypometabolism. Thirty-two patients who had undergone temporal lobectomy for treatment of MTLE and who completed both presurgical FDG-PET and comprehensive neuropsychological investigations with widely used standardized measures were included. Age-adjusted composite measures were calculated for verbal memory, nonverbal memory, relative material-specific memory, IQ, executive function, attention/working memory, and psychomotor speed. Fluorodeoxyglucose positron emission tomography was analyzed with statistical parametric mapping (SPM) to identify hypometabolism relative to healthy controls. Pearsons correlation was used to determine the relationship between regions of hypometabolism and neuropsychological functioning. Dominant temporal lobe hypometabolism was associated with relatively inferior verbal memory, while nondominant temporal lobe hypometabolism was associated with inferior nonverbal memory. No relationship was found between performance on any frontal lobe measures and prefrontal hypometabolism. Statistical parametric mapping-quantified lateralized temporal lobe hypometabolism correlates with material-specific episodic memory impairment in MTLE. In contrast, prefrontal hypometabolism is not associated with performance on frontal lobe measures. We suggest that this is because frontal lobe neuropsychology tests may not be good measures of isolated frontal lobe functioning.

Long duration between presentation of probable anti-N-methyl-D-aspartate receptor encephalitis and either clinical relapse or positive serum autoantibodies

Anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis is an autoimmune encephalitis first described in 2007. This condition has a well-characterised clinical phenotype with a multistage presentation beginning with prodromal symptoms, psychosis, cognitive deficits, and seizures, which can progress to involve movement disorders, catatonia, autonomic instability, and central hypoventilation requiring ventilatory support. Our first patient demonstrates, to our knowledge, the longest duration between the presentation of anti-NMDAR encephalitis and clinical relapse that has thus far been described. Our second patient highlights a clinical scenario where positive serum autoantibodies are demonstrated six years following complete clinical recovery, in the absence of clinical features of a relapse or a malignancy on screening. These patients highlight the importance of long-term follow up and tumour surveillance, and the role of electroconvulsive therapy in the management of catatonia. These cases also support the need for future studies evaluating the role of maintenance immunosuppression in patients at high risk for relapses.

Myoclonic status epilepticus as a presentation of caspr2 antibody‐associated autoimmune encephalitis

We present a case of autoimmune encephalitis associated with antibodies targeting contact in-associated protein-like 2. This case is notable because of the presentation with myoclonic status epilepticus and the prolonged clinical course of refractory seizures, which are demonstrated in the accompanying videos, and not previously associated with this condition. Treatment with prednisone, intravenous immunoglobulin, plasma exchange, rituximab, cyclophosphamide, and mycophenolate mofetil resulted in significant functional improvement. Historically, myoclonic status epilepticus is associated with a grave prognosis and minimal chance of meaningful recovery. This case demonstrates that autoimmune encephalitis remains an important differential diagnosis in patients with such a presentation, and that early recognition and the appropriate institution of immunotherapy can result in seizure control and functional recovery. [Published with video sequences].