A case of startle epilepsy and SSMA seizures documented with subdural recordings

Startle-Induced Epileptic Spasms: A Clinical and Video-EEG Study

Objective

This study aimed to delineate the detailed characteristics of startle-induced epileptic spasms (ES) and explore the brain regions where startle-induced ES originated.

Methods

Among 581 patients with ES registered in our database, 30 were diagnosed with startle-induced ES according to video-electroencephalogram (EEG) and seizure semiology and were included in this study. Patients' clinical characteristics and ictal high-frequency oscillations (HFOs) were analyzed.

Results

Mean age at the onset of startle-induced ES was 28.1 months. Half of the patients had structural etiology, two of whom were diagnosed with co-existing structural and genetic etiologies. The focal neuroimaging abnormalities were predominant in the frontal cortex (9/15, 60.0%). Fifteen patients (50%) had prominent interictal epileptiform discharges in the frontal and anterior temporal. Ictal HFOs counts of the startle-induced ES in the anterior region were significantly higher than those in the posterior regions (p < 0.05). Five patients (16.7%) became seizure-free ≥6 months, and ten (33.3%) showed startle-induced ES cessation ≥6 months. All patients except one had mild to severe psychomotor developmental delay after the onset of seizures.

Conclusion

Patients with startle-induced ES typically had brain lesions and showed drug-resistant. The neuroimaging and EEG findings, including ictal HFOs, support that startle-induced ES often originates from the frontal cortex.

The Involvement of Sensory-motor Networks in Reflex Seizure

Reflex seizures are epileptic events triggered by specific external stimuli, or less commonly, internal mental stimuli. Understanding the characteristics of reflex seizures is important to elucidate the mechanisms underlying network abnormalities in epileptic conditions. This report details a patient with medically intractable reflex seizures provoked by sensory stimuli to the patient's right foot. Single-photon emission computed tomography (SPECT) during the seizure induced by sensory stimulation showed hyperperfusion in broad sensory-motor networks (dorsal column-medial lemniscus pathway, left thalamus, bilateral postcentral gyri and posterior parietal cortices, left supplementary motor area (SMA), and left paracentral lobule) and left caudateputamen. The irritative zones and ictal onset zone were localized to the left medial frontoparietal (SMA, anterior and middle cingulate gyrus, and paracentral lobule) and lateral posterior parietal cortices, as evidenced by amelioration of reflex seizures following intracranial electroencephalography and surgical resection of these areas. The neuroradiological and electrophysiological findings in our case study illustrate that the mechanism of reflex seizures may be associated with hyperexcitability of the broad sensory-motor networks, including the basal ganglia. Disconnection of these networks is necessary to treat reflex seizures.

Seizure-free after surgery in a patient with non-lesional startle epilepsy: a case report

We present the case of a patient with startle epilepsy provoked by auditory, somatosensory and visual stimuli during video-electrocorticography (ECoG) recording. Ictal ECoG of all types of seizures triggered by the three kinds of stimuli showed that seizure onset originated from the left supplementary sensorimotor area (SSMA). The patient has been seizure-free after the cortex around the left SSMA only had been resected. Therefore, we speculate that left SSMA is the epileptogenic zone of startle epilepsy in this patient and perhaps the primary cortex to modulate the startle reflex in healthy persons.

A clinical and magnetoencephalography study of MRI-negative startle epilepsy

OBJECTIVE

The goal of this study was to investigate clinical findings, ictal semiology, and results of video/electroencephalography (video/EEG), and magnetoencephalography (MEG) in patients with startle epilepsy and normal brain MRI.

METHODS

Four patients (mean age 12.5 years) with startle epilepsy were investigated with MRI, video/EEG, and MEG.

RESULTS

Epilepsy diagnosis was established in childhood, and all had spontaneous and reflex seizures. Reflex seizures were triggered by sudden, unexpected sounds and tactile stimuli. The neurological examinations and MRIs were normal. MEG recordings showed focal epileptiform activity. An ictal MEG was obtained in one patient. Source modeling yielded dipole sources in right central frontal region.

CONCLUSION

The present study demonstrates that the origin of epileptiform activity in startle epilepsy can be localized in brain areas associated with supplementary motor seizures, even in patients with normal brain MRI. MEG adds complementary information to the localization of epileptiform activity and can be useful in planning invasive studies in cases evaluated for epilepsy surgery.

Intractable reflex audiogenic seizures in Aicardi syndrome

Aicardi syndrome (AS) is a rare disorder which includes the triad of total or partial agenesis of the corpus callosum, infantile spasms, and chorioretinal anomalies. Seizures and electroencephalogram findings observed in AS are polymorphic with both focal and generalized seizures. We first report on a patient affected by AS who presented with reflex audiogenic seizures specifically triggered by the starting tune of a popular television news. No other type of stimuli, either simple or complex, were able to precipitate the seizures in the patient. The severe cortical-subcortical lesions commonly observed in AS are associated with hyperexcitability of the cortices and may well account for the broad electroclinical patterns noted in this group of patients. From our report, the context of these patterns should be extended to include reflex audiogenic seizures.

Reflex Seizures in Patients with Malformations of Cortical Development and Refractory Epilepsy

PURPOSE

Malformations of cortical development (MCDs) are usually highly epileptogenic, and their hyperexcitability could facilitate the occurrence of reflex seizures. We sought to characterize reflex seizures in patients with MCDs and refractory epilepsy.

METHODS

Clinical, electrographic, and neuroimaging data were reviewed in eight patients with MCDs who had reflex seizures reproduced during presurgical evaluation.

RESULTS

All eight patients had both reflex and spontaneous seizures. In six, however, drop attacks or axial myoclonic seizures occurred only upon specific sensory stimulation. Reflex seizures were induced by more than one type of stimulus in most patients, but anatomofunctional correlations could usually be invoked. Six patients had significant intellectual impairment. Surgical resection controlled seizures in two patients.

CONCLUSIONS

Reflex seizures in patients with MCDs may be medically refractory and may often manifest as drop attacks or axial myoclonus. Surgical resection of focal lesions can bring reflex seizures under control. Putative mechanisms related to the relatively low frequency of reflex seizures in MCDs are discussed.

Epileptic and imaging findings in perinatal hypoxic-ischemic encephalopathy with ulegyria

Hypoxic-ischemic encephalopathy due to fetal or neonatal asphyxia is a major cause of acute mortality and chronic disability involving cerebral palsy, seizures, and mental retardation. The gestational age of the infant is one of the main variables determining the neuropathological picture of hypoxic-ischemic brain injury, and ulegyria (one of its neuropathological correlates) typically affects full-term infants. The damage usually involves the deeper sulcal portion of the convolutions while sparing the crowns, and includes subcortical white matter atrophy and gliosis. The aim of this study was to characterize the electroclinical features of hypoxic-ischemic encephalopathy when ulegyria is one of its main neuropathological features. To this end, nine patients with MRI-proven ulegyria and epilepsy underwent a complete neurological work-up. The ulegyric lesions were mainly distributed in the parasagittal watershed areas and frequently associated with other hypoxic-ischemic lesions. The neurological picture was characterized in most patients by mental retardation, motor deficits, and drug-refractory partial epilepsy. The ulegyria in our patients was associated with a complex clinical picture: epilepsy was a prominent component, and its severity directly correlated with the extent of the ulegyria and the associated hypoxic-ischemic lesions. Drug refractoriness was an almost constant correlate of this form of symptomatic epilepsy.

Restricted frontomesial epileptogenic focus generating dyskinetic behavior and laughter

PURPOSE

Substantial data are missing about the anatomic location of frontal regions supporting gelastic seizures.

METHODS

We report the results of stereo-electro-encephalographic recordings performed over several distinct functional premotor and executive fields in a patient whose seizures were characterized by dyskinetic behavior and ictal laughter, in the absence of cerebral MRI abnormalities.

RESULTS

The epileptogenic zone was circumscribed in the anterior and ventral part of the supplementary motor area and the underlying dorsal cingulate cortex. There were no or little spreading to cortical neighboring areas. The patient is seizure-free (follow-up of 27 months) after a stereotactic electric radiofrequency lesion of the epileptogenic focus.

CONCLUSION

The present data suggest that pericingulate premotor areas are involved in the triggering of the motor component of laughter. In this case, the coexistence of paroxysmal dyskinesias during laughter might reflect the involvement of specific compartment(s) of the basal ganglia.