Progression of myoclonus subtypes in subacute sclerosing panencephalitis.

OBJECTIVES: Diagnostic criteria of subacute sclerosing panencephalitis (SSPE) include myoclonus, a well-recognized clinical feature. Here, we studied the electrophysiological features of myoclonus with regards to disease staging in SSPE patients. METHODS: We included 10 patients diagnosed with SSPE between 2010 and 2018, along with 21 healthy subjects. All participants had detailed electrophysiological evaluation including polymyographic analysis, blink reflex after trigeminal stimulation, auditory startle response, startle response after somatosensory stimuli, F-waves, and long-loop reflexes. Clinical findings were retrieved from the medical records. RESULTS: Patients were categorized into Gascon stage 2B (n = 5, 50%), 2A (n = 2, 20%), 3B (n = 2, 20%) and 4A (n = 1, 10%) at the time of electrophysiological evaluation. Two patients had cortical myoclonus, four had possible cortico-subcortical myoclonus, and four had brainstem myoclonus. Patients were categorized into Gascon stages 2a and 2b had possible cortico-subcortical myoclonus (85.7%). However, none of the patients with stage 3b or 4a had possible cortico-subcortical subtype but all had the brainstem subtype. CONCLUSION: Association was seen between subtypes of myoclonus and clinical staging in SSPE. This suggests that myoclonus in SSPE may primarily involve the cortex and cortico-subcortical structures such as the thalamus at earlier stages of disease, and then involve more caudal structures as the disease progresses.

Long-term follow-up of two siblings with adult-onset neuronal ceroid lipofuscinosis, Kufs type A.

Reports on the clinical presentation of adult-onset neuronal ceroid lipofuscinoses (NCL) are scarce compared to infantile- and childhood-onset forms. Here, we aimed to present detailed temporal evolution of clinical and electrophysiological features of two siblings with adult-onset NCL and homozygous mutation in the CLN6 gene. We retrospectively analysed medical records and electrophysiological data in order to delineate evolution of clinical and electrophysiological findings. Electrophysiological studies included routine EEG and video-EEG, as well as polymyographic analysis of myoclonus and brainstem reflex studies. Both patients had seizures and cerebellar signs. Despite the slow progression of ataxia, they developed no mental deterioration, but had severe obsessive compulsive disorder and depression. EEG revealed frequent generalized spikes, polyspikes, and waves, prominent on awakening and during photic stimulation without significant change throughout the clinical course. Abnormalities concerning the blink reflex, auditory startle response, and startle response to somatosensory inputs manifested within four years. The patients underwent transient and mild improvement with valproate, whereas ataxia and seizures were dramatically ameliorated following high-dose piracetam. Patients with adult-onset NCL may present with slowly progressive ataxia, persistent photosensitivity, and seizures without dementia or extrapyramidal findings. Brainstem abnormalities become more evident with time, in line with ataxia. Piracetam is effective for both seizures and ataxia.

Startle Response in Progressive Myoclonic Epilepsy.

Cortical reflex myoclonus is a typical feature of progressive myoclonic epilepsy (PME) in which it is accompanied by other types of mostly drug-resistant seizures and progressive neurological signs. Although PME is characterized by cortical hyperexcitability, studies have demonstrated atrophy and degenerative changes in the brainstem in various types of PME. Thus, we have questioned whether any stimuli may trigger a hyperactive response of brainstem reticular formation in PME and investigated the startle reflex in individuals with PME. We recorded the auditory startle response (ASR) and the startle response to somatosensory inputs (SSS) in patients with PME, and compared the results with healthy volunteers and patients with other types of drug-resistant epilepsy. All patients were using antiepileptic drugs (AEDs), 12 were on multiple AEDs. The probability of ASR was significantly lower and mean onset latency was longer in patients with PME compared with other groups. SSS responses over all muscles were low in both the PME and drug-resistant epilepsy groups; however, the differences were not statistically significant. The presence of a response over the biceps brachii muscle was zero in the PME group and showed a borderline difference compared with the other groups. Decreased probability and prolonged latencies of ASR in PME indicate inhibition of reflex circuit. A trend for decreased responses of SSS suggests hypoactive SSS in both PME and other epilepsy groups. Hypoactive ASR in PME and hypoactive SSS in both PME and other epilepsies may be attributed to the degeneration of pontine reticular nuclei in PME and functional inhibition by AEDs in both disorders.

Electrophysiological findings in Rasmussen's syndrome.

Rasmussen syndrome is a rare, inflammatory and probably autoimmune disease presenting with epilepsia partialis continua which is generally in the form of myoclonic jerks and involves the upper extremities with or without head involvement. We sought to demonstrate the electrophysiological features in patients with Rasmussen syndrome. We performed continuous electrophysiological recordings of involuntary movement, as well as recordings of startle responses and long latency reflex in three patients with a diagnosis of Rasmussen syndrome. Positive and negative myoclonus were recorded. Startle responses were found to be suppressed. However, long latency reflexes were high in amplitude and one patient even had a C reflex. Stimulus-sensitive positive and negative cortical myoclonus are typical in epilepsia partialis continua of Rasmussen syndrome and degeneration of brainstem and reticulospinal pathways may develop in Rasmussen syndrome.

Blink reflex in progressive myoclonic epilepsies.

PURPOSE: Progressive myoclonic epilepsies (PME) include a heterogeneous group of disorders. The brainstem is involved in these disorders, as demonstrated by neuroimaging and autopsy studies. The blink reflex (BR) is characteristically elicited after supraorbital electrical stimulation. The BR has two components, an ipsilateral R1 and bilateral R2 (R2 and R2c). The central generator of the BR is the brainstem. In this study, we aimed to investigate the functional status of the brainstem using the BR in PME cases with different etiological factors. METHODS: We prospectively included 17 patients with a diagnosis of PME (8 male, 47.1%) who were examined between June 2009 and June 2012. For comparison, we included 41 healthy volunteers (18 male 43.9%) who did not have any neurological or systemic diseases. We recorded responses bilaterally over the orbicularis oculi muscles after supraorbital stimulation in all participants. RESULTS: The R1 and R2 components of the BR were obtained in all healthy subjects with normal latencies, whereas abnormalities in the R2 and R2c components were observed at significantly higher rates in the PME patients. The mean latencies of the bilateral R2 and R2c components were significantly prolonged, and the amplitudes were diminished in the PME patients. Disease duration and the use of multiple antiepileptic drugs were related to abnormal R2s. CONCLUSION: The abnormalities of the R2 and R2c components of the BR confirmed the inhibition of the reticular formation. The findings are probably related to disease processes and partially due to the use of multiple antiepileptic drugs.