Peripheral Neuropathy in Spinocerebellar Ataxia Type 1, 2, 3, and 6.

Spinocerebellar ataxias (SCAs) are characterized by autosomal dominantly inherited progressive ataxia but are clinically heterogeneous due to variable involvement of non-cerebellar parts of the nervous system. Non-cerebellar symptoms contribute significantly to the burden of SCAs, may guide the clinician to the underlying genetic subtype, and might be useful markers to monitor disease. Peripheral neuropathy is frequently observed in SCA, but subtype-specific features and subclinical manifestations have rarely been evaluated. We performed a multicenter nerve conduction study with 162 patients with genetically confirmed SCA1, SCA2, SCA3, and SCA6. The study proved peripheral nerves to be involved in the neurodegenerative process in 82 % of SCA1, 63 % of SCA2, 55 % of SCA3, and 22 % of SCA6 patients. Most patients of all subtypes revealed affection of both sensory and motor fibers. Neuropathy was most frequently of mixed type with axonal and demyelinating characteristics in all SCA subtypes. However, nerve conduction velocities of SCA1 patients were slower compared to other genotypes. SCA6 patients revealed less axonal damage than patients with other subtypes. No influence of CAG repeat length or biometric determinants on peripheral neuropathy could be identified in SCA1, SCA3, and SCA6. In SCA2, earlier onset and more severe ataxia were associated with peripheral neuropathy. We proved peripheral neuropathy to be a frequent site of the neurodegenerative process in all common SCA subtypes. Since damage to peripheral nerves is readily assessable by electrophysiological means, nerve conduction studies should be performed in a longitudinal approach to assess these parameters as potential progression markers.

Evolution of clinical, electrophysiological, and radiological aspects of the carpal tunnel syndrome before and after surgery.

The aim of the study was to analyze the evolution of the clinical, electrophysiological, and ultrasound aspects of carpal tunnel syndrome (CTS) before and 4 and 8 weeks after surgery. A Boston Carpal Tunnel Questionnaire, an ultrasound scan, and an electrophysiological exam were performed in 14 patients the day of surgery, 4 and 8 weeks after. The nerve conduction study included: median nerve sensory conduction stimulating digit 3 and 4, median motor conduction from the abductor pollicis brevis, ulnar nerve sensory, and motor conduction. A significant improvement of the symptoms and a significant decrease of the median nerve proximal cross-sectional area on the ultrasound scan were observed 4 weeks after surgery. Distal motor latency (DML) was > 4.2 ms in six patients and decreased along the three visits. DML was ≤ 4.2 ms in the eight others and stayed stable after surgery. We observed a significant increase of the sensory median nerve amplitude response at the wrist stimulating the third digit 8 weeks after surgery. When operated patients are referred for control, we recommend to perform: (1) 4 weeks after surgery, an ultrasonography, and a measure of the DML of the median nerve; (2) 8 weeks after surgery, a measure of the sensory conduction velocity of the median nerve.