Abstracts

Rationale: Spinocerebellar ataxias (SCA) are a heterogenous group of autosomal dominant disorders that result in degeneration of the cerebellum and thus result in ataxia. A growing number of genetic mutations have been identified that can cause SCA, many of which have unique clinical features that distinguish them from the other types. Certain types of SCA predispose affected individuals to experience seizures. We monitored one such individual with laboratory confirmed SCA 10 in our epilepsy monitoring unit, and report his unique EEG findings that have not been previously reported in the medical literature. The presence of generalized and focal epileptiform abnormalities on this patients EEG also raises questions about genetic forms of epilepsy that have been hithertofor unreported. Methods: A 33 year old Mexican male was referred to our tertiary care center for progressive gait disturbance, clumsiness, and seizures. History obtained from the patient identified several immediate and extended family members that were similarly affected. Examination revealed nystagmus, marked appendicular ataxia, and myoclonus. Neuroimaging studies demonstrated severe cerebellar degeneration. EEG monitoring demonstrated intermittent generalized spike and wave discharges, as well as focal left temporal sharp waves. An autosomal dominant SCA panel confirmed the diagnosis of SCA 10. A literature search was performed to determine the typical EEG pattern seen in SCA 10, given the unique pattern of generalized as well as focal epileptiform abnormalities seen on this patient's EEG. A literature review of EEG findings in genetic forms of epilepsy was also performed. Results: The previously reported EEG abnormalities seen in patients with SCA 10 are diffuse slowing with or without focal epileptiform discharges. Our literature search did not identify any prior reports of our patient's pattern in patients with SCA 10, or in any other type of SCA. Furthermore, this pattern of focal and generalized epileptiform discharges is felt to be relatively uncommon in patients with epilepsy, in general. Though the body of information around genetic forms of epilepsy is growing, few proposed theories have addressed this particular aspect of hereditary epilepsy in which focal and diffuse epileptiform abnormalities are found. Conclusions: Certain types of SCA predispose patients to experience seizures. We have identified one patient with SCA 10 whose EEG showed generalized and focal epileptiform abnormalities, a pattern previously not described in the medical literature in this setting. Proposed mechanisms for genetic causes of epilepsy should incorporate theory that accounts for both generalized and focal-onset seizures.