Involvement of the cranial nerves and their nuclei in spinocerebellar ataxia type 2 (SCA2).

Although the cranial nerves, their nuclei and related fiber tracts are crucial for a variety of oculomotor, somatomotor, somatosensory, auditory, vestibular-related, autonomic and ingestion-related functions, knowledge regarding the extent of their involvement in spinocerebellar ataxia type 2 (SCA2) patients is incomplete. Accordingly, we performed a pathoanatomical analysis of these structures in six clinically diagnosed SCA2 patients. Unconventionally thick serial sections through the brainstem stained for lipofuscin pigment (aldehyde-fuchsin) and Nissl material (Darrow red) showed that all oculomotor, somatomotor, somatosensory, auditory, vestibular and autonomic cranial nerve nuclei may undergo neurodegeneration during SCA2. Similarly, examination of myelin-stained thick serial sections revealed that nearly all cranial nerves and associated fiber tracts may sustain atrophy and myelin loss in SCA2 patients. In view of the known functional role of the affected cranial nerves, their nuclei and associated fiber tracts, the present findings provide appropriate pathoanatomical explanations for some of the disease-related and unexplained symptoms seen in SCA2 patients: double vision, gaze palsy, slowing of saccades, ptosis, ingestion-related malfunctions, impairments of the optokinetic nystagmus and the vestibulo-ocular reaction, facial and tongue fasciculation-like movements, impaired centripetal transmission of temperature-related information from the face, dystonic posture of the neck, as well as abnormalities of the brainstem auditory evoked potentials.

[Cuban dominant cerebellar ataxia. Peripheral nerve conduction studies in patients and asymptomatic relatives]. / Ataxia cerebelosa dominante Cubana. Estudios de conducción de nervios periféricos en pacientes y familiares asintomáticos.

A total of 59 relatives of patients suffering from Cuban Dominant Cerebellar Ataxia (SCA2) were studied, undergoing physical examination in order to evaluate them clinically as well as by studies of peripheral nerve conduction. Clinical manifestations were detected in 13 of these patients. In 11 other patients there were electrophysiological alterations without symptoms or signs. The main electrophysiological alterations detected were reduced amplitude of the sensitive potentials. This is an expression of an axonal lesion occurring at a presymptomatic stage.

Ataxia cerebelosa dominante Cubana. Estudios de conducción de nervios periféricos en pacientes y familiares asintomáticos. / [Cuban dominant cerebellar ataxia. Peripheral nerve conduction studies in patients and asymptomatic relatives]

A total of 59 relatives of patients suffering from Cuban Dominant Cerebellar Ataxia (SCA2) were studied, undergoing physical examination in order to evaluate them clinically as well as by studies of peripheral nerve conduction. Clinical manifestations were detected in 13 of these patients. In 11 other patients there were electrophysiological alterations without symptoms or signs. The main electrophysiological alterations detected were reduced amplitude of the sensitive potentials. This is an expression of an axonal lesion occurring at a presymptomatic stage.

Moderate expansion of a normally biallelic trinucleotide repeat in spinocerebellar ataxia type 2.

The gene for spinocerebellar ataxia type 2 (SCA2) has been mapped to 12q24.1. A 1.1-megabase contig in the candidate region was assembled in P1 artificial chromosome and bacterial artificial chromosome clones. Using this contig, we identified a CAG trinucleotide repeat with CAA interruptions that was expanded in patients with SCA2. In contrast to other unstable trinucleotide repeats, this CAG repeat was not highly polymorphic in normal individuals. In SCA2 patients, the repeat was perfect and expanded to 36-52 repeats. The most common disease allele contained (CAG)37, one of the shortest expansions seen in a CAG expansion syndrome. The repeat occurs in the 5'-coding region of SCA2 which is a member of a novel gene family.

Autosomal dominant cerebellar ataxia: clinical analysis of 263 patients from a homogeneous population in Holguín, Cuba.

We describe 263 patients with autosomal dominant cerebellar ataxia from the Holguín province, Cuba. There is evidence of a common ancestry and the population represents the largest homogeneous group of patients yet described. Primary features include gait ataxia, dysarthria, dysmetria, adiadochokinesia, cramps, tremor, hypotonia, abnormal reflexes, and slowed/limited eye movements. Age at onset ranged from 2 to 65 years. There was considerable clinical variability within the families. No patients had optic atrophy, spasticity, pigmentary retinal degeneration, or cogwheel rigidity, and only 1 had dementia.