Aphasic or amnesic status epilepticus detected on PET but not EEG

Abstract

Summary Purpose: To describe five patients with ictal aphasia and one patient with ictal amnesia, who had focal positron emission tomography (PET) hypermetabolism but no clear ictal activity on electroencephalography (EEG). Methods: 18F‐Fluorodeoxyglucose (FDG)–PET scans with concomitant EEG were obtained in five patients with suspected ictal aphasia or ictal amnesia without ictal activity on EEG. We reviewed medical history, EEG, imaging data, and treatment outcome. Results: Brain magnetic resonance imaging (MRI) showed no structural abnormalities in any of the patients. EEG showed left temporal irregular delta activity in three patients, with aphasia and nonspecific abnormalities in two other patients, all without clear ictal pattern. All patients demonstrated focal hypermetabolism on PET scan. The hypermetabolism was in the left frontotemporal region in patients with ictal aphasia and in the bilateral hippocampal region in the patient with amnesia. Three patients who received intravenous benzodiazepines during their episodes had transient clinical improvement. With antiepileptic drug (AED) treatment, symptoms gradually resolved in all patients. Concomitant resolution of PET hypermetabolism was documented in three patients who had follow up scans. One patient with ictal aphasia later developed recurrent episodes, each with recurrent PET hypermetabolism. This patient and one other patient required immune‐modulating therapy in addition to AEDs. Discussion: FDG‐PET imaging should be considered as a diagnostic tool in patients with suspected ictal aphasia or amnesia, who fail to show clear evidence of ictal activity on EEG.

Recurrent epileptic Wernicke aphasia

“…Fluctuation in the level of speech impairment and inter-ictal EEG abnormality in our patient may suggest a combination of recurrent seizure and post-ictal deficit as a mechanism for prolonged aphasia. Aphasic status epilepticus, similar to simple partial status epilepticus, may be associated with non-ictal scalp EEG, however ictal activity by intracranial EEG recording or focal hypermetabolism on PET scan has been documented in such patients [3,5,6]. A PET or SPECT scan was not performed in our patient.…”

“…Aphasic seizures in almost all cases arise from the dominant hemisphere [2,3]. Epileptic focus in ictal WA has been reported in the left Journal of the Neurological Sciences 291 (2010) 98-99 temporo-parietal area, left fronto-temporal region, or basal temporal language area, based on findings of ictal EEG and/or PET scan hypermetabolism [2,3,5,6].…”

De novo status epilepticus with isolated aphasia

“…Ericson et al [19] found standard EEG (30 min) in aphasic status epilepticus to be sensitive in only 5/9 (56%) patients, while continuous EEG confirmed seizure activity. Dong et al [20] showed aphasic NCSE in 5 patients with (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET), while EEG failed to show clear ictal activity.…”

Prolonged ictal aphasia: A diagnosis to consider

“…In one patient in whom aphasia lasted for 1 week (initially diagnosed as post IA), intracranial electrode monitoring revealed that the patient had prolonged IA. 6 In one case series of four patients with IA, surface EEG did not reveal obvious ictal patterns and the ictal state was diagnosed by a positron emission tomography (PET) scan only. 7 Our series of patients showed that surface EEG is a good and simple way to diagnose IA.…”