Surgery removes EEG abnormalities in patients with Chiari type I malformation and poor CSF flow.

OBJECTIVE: To study the outcome of EEG from patients with Chiari I malformations and nonspecific EEG abnormalities, after posterior fossa decompression and CSF flow normalization. METHODS: Three 'apparently asymptomatic' children who had been diagnosed with Arnold-Chiari type 1 EEG abnormalities and who exhibited (a) a wide range of abnormalities according to common anatomical Chiari MRI classifications (Elster AD, Chen MY. Chiari I malformations: clinical and radiologic reappraisal. Radiology 1992;183:347-53), (b) a lack of specific, clinical signs of increased intracranial pressure, and (c) apparently unrelated, EEG-nonspecific abnormalities (focal intermittent rhythmic delta activity (IRDA)--solely in patients 1 and 3, and with focal IRDA plus spikes and spike waves of high voltage in patient 2). Standard EEGs were recorded before surgery and within one month of surgery, which was performed in conjunction with intraoperative echo-Doppler ultrasonography to control CSF flow. Subsequent EEGs and clinical follow-ups were performed within 6-12 months of surgery. RESULTS: In all patients, intraoperative echo-Doppler ultrasonographic control demonstrated poor CSF flow, which was completely restored by posterior fossa decompression. In all patients, the EEG abnormalities disappeared within one month of surgery and the EEGs were normal at follow-up. CONCLUSIONS: A new CNS symptom, identified as focal IRDA alone or focal IRDA plus spikes and spike waves of high voltage in the EEG, seems to be associated with poor CSF flow in 'apparently asymptomatic' patients with Chiari type I malformations. SIGNIFICANCE: The identified, paroxysmal EEG abnormalities should be interpreted as an indirect sign of subtle CNS distress.

Myoclonic encephalopathy in the CDKL5 gene mutation.

OBJECTIVE: Epilepsy with mutation of the CDKL5 gene causes early seizures and is a variant of Rett syndrome (MIM (312750), which is reported typically as infantile spasms. The purpose of this study was to analyze the epileptic histories and EEGs of patients with the CDKL5 mutation. METHODS: We reviewed the epilepsy histories and electroclinical analyses of three girls aged 9.5, 7.4, and 9.4 years, each with a mutation of the CDKL5 gene. RESULTS: We revealed the presence of an encephalopathy that started by 1.5 months of age. At first, seizures involved tonic spasms or complex partial seizures, and were complicated by the later appearance of complex partial, tonic, and unexpectedly, myoclonic seizures. This form of epilepsy was drug resistant. Routine and prolonged video EEGs both displayed a homogeneous electroclinical pattern consisting of (a) unique background with diffuse high voltage sharp waves of 6-7 Hz, and absence of the typical rhythmic frontal-central theta activity present in Rett syndrome; (b) unique awake and sleep background, with diffuse, high voltage, continuous sharp waves with multifocal and diffuse spikes; (c) rhythmic, diffuse, 15 Hz activity accompanied clinically by tonic seizures; (d) intercritical pattern with pseudoperiodic, diffuse, sharp waves or pseudoperiodic, diffuse spike and polyspike or wave discharges; and (e) diffuse, spike, polyspike and wave discharges accompanied by massive or focal myoclonias or both. CONCLUSIONS: Patients with the CDKL5 mutation have an early onset, epileptic encephalopathy in infancy that evolves into myoclonic seizures in childhood with a unique EEG pattern. SIGNIFICANCE: Recognizing this type of encephalopathy could be useful in prompting clinicians to proceed further with their diagnostic work in patients not fitting the criteria of classical Rett syndrome.