ABSTRACT
Electrophysiological studies have been shown to be useful in hereditary ataxia, but only a small numberof patients have been studied, and the duration of the illness, serial studies and molecular definition have not been taken intoaccount. Objective. We proposed, by means of electrophysiological techniques, to characterize the functional evolutionary stateof the afferent and efferent systems in asymptomatic relations of patients with type 2 spinocerebellar ataxia (SCA2). Patients andmethods. A 10 year longitudinal, prospective study was made of 59 children of patients with SCA2. The sequence included fourstudies: 1986, 1991, 1994 and 1996, all with informed consent for the investigation. The control group consisted of 108volunteers. The electrophysiological studies recorded were: conduction studies in peripheral nerves and multimodal evokedpotentials. For statistical analysis multivariate methods were used with a confidence interval of 95% (a= 0.05). Results.Electrophysiological alterations were observed even in the absence of clinical signs, such as reduced amplitude of sensorypotentials, morphological changes and prolonged latency of the central components of somatosensory evoked potentials, andof brain stem auditory evoked potentials, whilst the visual evoked potentials remained normal. Of 79 relations studied duringthe 10 year investigation, 17 had clinical signs and were considered to be patients with SCA2. Conclusions. Four stages of theillness were defined: healthy, presymptomatic, and patients with and without nerve conduction block. These characterized thedegenerative mechanisms of the afferent and efferent systems of the relations of patients with SCA2 who became ill themselves...(AU)
Los estudios electrofisiológicos han mostradoutilidad en las ataxias hereditarias, pero el número de pacientesestudiados ha sido escaso, y no se han tenido en cuenta el tiempode evolución, los estudios seriados y la definición molecular. Objetivo.Caracterizar con técnicas electrofisiológicas el estado funcionalevolutivo de los sistemas aferentes y eferentes en familiares asintomáticosde enfermos con ataxia espinocerebelosa tipo 2 (AEC2).Pacientes y métodos. Se realizó un estudio longitudinal prospectivodurante 10 años a 59 hijos de pacientes con AEC2. La secuenciaincluyó cuatro estudios: 1986, 1991, 1994 y 1996 con el consentimientoinformado. El grupo control contó con 108 sujetos voluntarios.Registros electrofisiológicos realizados: estudios de conducciónen nervios periféricos y potenciales evocados multimodales. Enel análisis estadístico se aplicaron métodos multivariados con unaconfiabilidad del 95% (a= 0,05). Resultados. Se observó la existenciade alteraciones electrofisiológicas aun en ausencia de manifestacionesclínicas tales como disminución de las amplitudes de lospotenciales sensitivos, alteraciones en la morfología y prolongaciónde las latencias de los componentes centrales de los potencialesevocados somatosensoriales y cambios en la replicabilidad y morfologíade los potenciales evocados auditivos de tallo cerebral, mientraslos visuales permanecieron...(AU)
Subject(s)
Humans , Evoked Potentials, Somatosensory , Spinocerebellar Degenerations , Heat ConductionABSTRACT
Type 2 spinocerebellar ataxia (SCA2) is the condition most often described (to date) in patients withhereditary ataxia, its prevalence being 52 per 100,000 persons. In patients with SCA2 neurogenic patterns are identifiedby means of electrophysiological techniques. A transverse study was made of 70 persons with SCA2 ofdifferent periods of duration and from different regions of the country. The control group was made up of 108 volunteers.Electrophysiological recordings made were: conventional and quantitative electromyography, late F wave and H reflex responses.Multivariate methods with a confidence interval of 95 percent (a= 0.05) were used for statistical analysis. Results. Conventionalelectromyography showed a pattern of isolated contractions, predominantly in patients who had had the disorder £5 years,classified as Grade I by the authors; in those with a history of >5 years there was a pattern of very isolated contractions with motorpotentials of amplitudes >10 mV, without denervation, classified as Grade II. The patients with worse clinical condition wereconcentrated in this latter group. Significant differences were observed between Groups I, II and control and also regarding thelate responses of the F wave and H reflex. Conclusions. For the first time two types of neurogenic patterns of SCA2 have beenestablished to describe alterations which denote participation of the first and...(AU)
