Startle epilepsy with infantile hemiplegia: report of two cases improved by surgery

Comparing late-onset epileptic spasm outcomes after corpus callosotomy and subsequent disconnection surgery between post-encephalitis/encephalopathy and non-encephalitis/encephalopathy

OBJECTIVE

We aimed to analyze the efficiency of corpus callosotomy (CC) and subsequent disconnection surgeries in patients with late-onset epileptic spasms (LOES) by comparing post-encephalitis/encephalopathy (PE) and non-encephalitis/encephalopathy (NE). We hypothesized these surgeries can control potential focal onset epileptic spasms (ES) in the NE group but not in the PE group.

METHODS

We retrospectively included 23 patients (12 with PE and 11 with NE) who initially underwent CC and subsequent disconnection surgeries (five NE). We compared the clinical courses, seizure types, MRI, video-EEG, epilepsy surgery, and seizure outcomes between the two groups.

RESULTS

The median age of LOES onset in the PE group was 2.8 (range 1.0-10.1 years) and 2.9 years (range 1.1-12.6) in the NE group. Bilateral MRI abnormalities were observed in both groups (PE, n = 12; NE, n = 3; P < 0.05). The PE group presented ES alone (n = 2), ES + focal seizures (FS) (n = 3), ES + generalized seizures (GS) (n = 3), and ES + FS + GS (n = 4) in addition to stimulus-induced startle seizures (SS) (n = 8) (mean 3.1 seizure types/patient). The NE group presented ES alone (n = 1), ES + FS (n = 2), and ES + FS + GS (n = 8) (mean 2.7 seizure types/patient). In the PE group, CC stopped ES (n = 1) and SS (n = 1) and achieved <50% SS (n = 3). In the NE group, CC achieved immediate ES-free status (n = 2) and < 50% ES (n = 1), and additional disconnection surgeries subsided all seizure types (n = 3) based on lateralized interictal/ictal EEG findings. LOES was significantly remitted by surgery in the NE group (6/11 [55%]) compared with the PE group (1/12 [8%]) (P < 0.05).

SIGNIFICANCE

LOES is a drug-resistant, focal/generalized/unknown onset ES. Lateralization of ES in NE could be achieved after CC and eliminated by further disconnection surgeries because of potential focal onset ES. LOES in PE had little benefit from CC for generalized onset ES. However, CC might reduce SS in patients in the PE group with multiple seizure types.

Multiple Stereoelectroencephalography-Guided Radiofrequency Thermocoagulations for Polymicrogyria With Startle Seizures: A Case Report

The best results of stereoelectroencephalography (SEEG)-guided radiofrequency thermocoagulation (RF-TC) were observed in epilepsies with more limited lesions, but this procedure is rarely used in a wide range of brain malformation. We report a rare case of polymicrogyria (PMG) combined with drug-resistant startle seizures. Presurgical monitoring was performed using SEEG owing to the large lesion and complexity of PMG. According to the intracranial electrode results, the seizure onset was extensive, with the onset starting earlier in the cingulate sulcus and insular pole than in other sites of the other electrodes. Multi-point and multi-step SEEG-guided RF-TC was used for diffuse lesion and functional protection. RF-TC was first applied to the cingulate sulcus and insular pole, and our patient was rendered free from startle seizures after 2 weeks. Two weeks of observation helped us to observe the efficacy of RF-TC and the changes of SEEG, so as to make the next TC scheme. The patient still had spontaneous seizures after the first treatment. RF-TC was then applied to other sites involved earlier. Finally, the patient reached Engel class IIa for a follow-up period of 1 year. There were no additional startle seizures, and important functional areas were protected.

Multiple Subpial Transections for Medically Refractory Epilepsy: A Disaggregated Review of Patient-Level Data

BACKGROUND

Multiple subpial transections (MST) are a treatment for seizure foci in nonresectable eloquent areas.

OBJECTIVE

To systematically review patient-level data regarding MST.

METHODS

Studies describing patient-level data for MST procedures were extracted from the Medline and PubMed databases, yielding a synthetic cohort of 212 patients from 34 studies. Data regarding seizure outcome, patient demographics, seizure type, surgery type, and complications were extracted and analyzed.

RESULTS

Seizure freedom was achieved in 55.2% of patients undergoing MST combined with resection, and 23.9% of patients undergoing MST alone. Significant predictors for seizure freedom were a temporal lobe focus (odds ratio 4.9; 95% confidence interval 1.71, 14.3) and resection of portions of the focus, when feasible (odds ratio 3.88; 95% confidence interval 2.02, 7.45). Complications were frequent, with transient mono- or hemiparesis affecting 19.8% of patients, transient dysphasia 12.3%, and permanent paresis or dysphasia in 6.6% and 1.9% of patients, respectively.

CONCLUSION

MST is an effective treatment for refractory epilepsy in eloquent cortex, with greater chances of seizure freedom when portions of the focus are resected in tandem with MST. The reported rates of seizure freedom with MST are higher than those of existing neuromodulatory therapies, such as vagus nerve stimulation, deep brain stimulation, and responsive neurostimulation, though these latter therapies are supported by randomized-controlled trials, while MST is not. The reported complication rate of MST is higher than that of resection and neuromodulatory therapies. MST remains a viable option for the treatment of eloquent foci, provided a careful risk-benefit analysis is conducted.

Noninvasive treatment alternative for intractable startle epilepsy

We describe a treatment alternative for intractable, startle-provoked, epileptic seizures in four children aged between 8 and 14. Three of the four children had symptomatic localization-related epilepsy. They all suffered from intractable epilepsy precipitated by sudden sounds. The fact that seizures tended to occur with high frequency – more than one seizure a day – had a clear impact on daily life. Clinical seizure pattern demonstrated asymmetric tonic posturing in all four children. Three children experienced several seizure types including focal seizure onset. All children had focal neurological signs or learning disabilities or a combination of both. Our noninvasive treatment method using psychoeducational counseling and sound generators was applied in four children, resulting in a seizure frequency reduction of ≥ 50% in two of them.

Generalized versus partial reflex seizures: a review

In this review we assess our currently available knowledge about reflex seizures with special emphasis on the difference between "generalized" reflex seizures induced by visual stimuli, thinking, praxis and language tasks, and "focal" seizures induced by startle, eating, music, hot water, somatosensory stimuli and orgasm. We discuss in particular evidence from animal, clinical, neurophysiological and neuroimaging studies supporting the concept that "generalized" reflex seizures, usually occurring in the setting of IGE, should be considered as focal seizures with quick secondary generalization. We also review recent advances in genetic and therapeutic approach of reflex seizures.

Late-onset epilepsy in children with acute febrile encephalopathy with prolonged convulsions: A clinical and encephalographic study

The aim of this study is to analyze the characteristics of epilepsies as the sequelae of acute febrile encephalopathy with prolonged convulsions during childhood. Sixteen patients (M:F=9:7) aged 2-13years (mean 6.1years) with history of febrile acute encephalopathy were retrospectively reviewed. These patients experienced febrile encephalopathy at the age of 11months to 4years, with 11 individuals presenting with findings of a biphasic clinical course (n=5), frontal predominant (n=8) lesions, and/or reduced diffusivity in the cerebral white matter on magnetic resonance imaging (MRI; n=3). The remaining 5 patients had unilateral lesions that manifested the phenotype of hemiconvulsion-hemiplegia-epilepsy syndrome (HHES). Epilepsy emerged with a latent period of 2months to 2years after the acute phase of febrile encephalopathy. Head nodding or spasm with subsequent motion arrest and brief tonic seizures were the main seizure phenotypes. Ictal records of epileptic seizures were available in 9 patients. Epileptiform discharges with a focal or uneven distribution appeared at the seizure onset and lasted less than 1s in all patients; these were followed by either generalized attenuation or fast activity in 8 patients with head nodding, spasm, or brief tonic seizures, and by localized fast activity in 1 patient with versive tonic seizures. Notably, the seizure onset area was often located outside the severe lesions on MRI, i.e., in the parietal areas in patients with frontal predominant lesions, and in the spared hemisphere of HHES. Although phenobarbital, zonisamide, carbamazepine, clobazam, clonazepam, and clorazepate were partially effective in some patients, daily seizures persisted in 11 patients. Callosotomy was performed in 2 patients, and beneficial effects were observed in both. These characteristics suggested a broad distribution of augmented excitability in these patients, resulting in the rapid propagation of epileptic activity in the initial phase of ictal phenomena. Thus, this study investigates the most severe subgroup of epilepsy following febrile acute encephalopathy and provides the basis for further exploration of the pathogenesis and treatment of characteristic seizures in this population.

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.

Approach to pediatric epilepsy surgery: State of the art, Part II: Approach to specific epilepsy syndromes and etiologies

The second of this 2-part review depicts the specific approach to the common causes of pediatric refractory epilepsy amenable to surgery. These include tumors, malformations due to abnormal cortical development, vascular abnormalities and certain epileptic syndromes. Seizure freedom rates are high (usually 60-80%) following tailored focal resection, lesionectomy, and hemispherectomy. However, in patients in whom the epileptogenic zone overlaps with unresectable eloquent cortex, and in certain epileptic syndromes, seizure freedom may not be achievable. In such cases, palliative procedures such as callosotomy, multiple subpial transections and vagus nerve stimulation can achieve reduction in seizure severity but rarely seizure freedom. Integration of the new imaging techniques and the concepts of neuronal plasticity, the epileptogenic lesion, the ictal onset, symptomatogenic, irritative, and epileptogenic zones is an expanding and dynamic process that will allow us, in the future, to better decide on the surgical approach of choice and its timing.

Proven startle-provoked epileptic seizures in childhood: semiologic and electrophysiologic variability

PURPOSE

To delineate further the clinical and electrophysiologic features of proven startle-provoked epileptic seizures (SPESs) in children.

METHODS

Clinical, neuroradiologic, and neurophysiologic data of 22 consecutive patients with SPESs were analyzed. Eighty-nine SPESs were documented by video-EEG and evaluated with respect to semiology and ictal and interictal EEG findings.

RESULTS

Mean age was 68 months (10-178 months). Most children had severe mental retardation (86%). Neuroimaging demonstrated diffuse cerebral abnormalities in 15 of 19. Somatosensory evoked potentials revealed cortical abnormalities in 10 of 13 children. The underlying causes were heterogeneous. Only two patients were normally developed. Seizure frequency was usually high (>10/day). Two children had less frequent SPESs (two per month; two per week). Seizures were easily precipitated by sudden sound (n=15), unexpected touch (n=3), or both (n=4). The most common semiologic findings (50%) were generalized tonic seizures or those characterized by a predominant tonic phase, followed in frequency by myoclonic seizures (36%), which were generalized in seven, and unilateral in one. Generalized clonic seizures were observed in one. A complex seizure spread was documented in two children. The most common ictal EEG finding (60%) was a diffuse electrodecremental pattern (DEP). Generalized spike/polyspike waves were found in five and focal discharges in four.

CONCLUSIONS

Our results imply that startle epilepsy is not a uniform epileptic entity. We were able to demonstrate a number of distinct patterns of SPESs, characterized by clinical, semiologic, and electrophysiologic features. Considering the high diversity of SPES patients, a common underlying pathophysiologic mechanism seems unlikely.

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

PURPOSE

To study the mechanisms of startle-induced supplementary sensorimotor area (SSMA) seizures.

METHODS

We present a patient investigated with indwelling subdural grid electrodes covering both the SSMA and the dorsolateral frontal lobe.

RESULTS

We found a simultaneous seizure onset in the right dorsolateral premotor cortex and the right SSMA. High-resolution magnetic resonance imaging (MRI) showed a small subcortical lesion adjacent to the right SSMA. The patient became seizure free after resection of the lesion and the ictal-onset zone.

CONCLUSIONS

We conclude that an extended region of abnormally excitable tissue within the frontal lobe could facilitate the generation of startle-induced seizures. We speculate that a widespread epileptogenic zone could help to explain why some patients with SSMA or dorsolateral frontal lobe seizures are more likely to have startle-induced seizures.