Neurophysiological studies and non-motor symptoms prior to ataxia in a patient with machado-joseph disease: trying to understand the natural history of brain degeneration

Sleep Alterations in a Mouse Model of Spinocerebellar Ataxia Type 3

Spinocerebellar ataxia type 3 (SCA3) is a neurodegenerative disorder showing progressive neuronal loss in several brain areas and a broad spectrum of motor and non-motor symptoms, including ataxia and altered sleep. While sleep disturbances are known to play pathophysiologic roles in other neurodegenerative disorders, their impact on SCA3 is unknown. Using spectrographic measurements, we sought to quantitatively characterize sleep electroencephalography (EEG) in SCA3 transgenic mice with confirmed disease phenotype. We first measured motor phenotypes in 18-31-week-old homozygous SCA3 YACMJD84.2 mice and non-transgenic wild-type littermate mice during lights-on and lights-off periods. We next implanted electrodes to obtain 12-h (zeitgeber time 0-12) EEG recordings for three consecutive days when the mice were 26-36 weeks old. EEG-based spectroscopy showed that compared to wild-type littermates, SCA3 homozygous mice display: (i) increased duration of rapid-eye movement sleep (REM) and fragmentation in all sleep and wake states; (ii) higher beta power oscillations during REM and non-REM (NREM); and (iii) additional spectral power band alterations during REM and wake. Our data show that sleep architecture and EEG spectral power are dysregulated in homozygous SCA3 mice, indicating that common sleep-related etiologic factors may underlie mouse and human SCA3 phenotypes.

Non-motor and Extracerebellar Features in Spinocerebellar Ataxia Type 2

Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominant degenerative disease. Pathological studies have demonstrated not only cerebellar and brainstem atrophy, but substantia nigra, motoneurons, basal ganglia, thalamus, and peripheral nerves involvement. These findings may explain non-motor and extra-cerebellar features in SCA2. We accessed the non-motor symptoms and extra-cerebellar signs in SCA2 patients in order to provide a better understanding on pathophysiological mechanisms and natural history of brain degeneration in the disease. Thirty-three SCA2 patients were evaluated and compared with 26 healthy subjects. We investigated the following variables: sleep disorders, cognitive deficit, olfactory impairment, urinary dysfunction, psychiatric symptoms, cramps, pain, movement disorders, and weight loss. SCA2 had a high frequency of REM sleep behavior disorder (48.48 %, N = 16) as well as excessive daytime sleepiness (42.42 %, N = 14). Chorea was present in 15.15 % (N = 5), dystonia in 27.27 % (N = 9), and parkinsonism in 27.27 % (N = 9). Slow saccadic pursuit was present in 87.87 % (N = 29) and ophtalmoparesis in 78.78 % (N = 26) of patients. Regarding sleep disorders, 18.18 % (N = 6) of patients had restless leg syndrome. Dysphagia was present in 39.39 % (N = 13), weight loss 24.24 % (N = 8), and urinary dysfunction 27.27 % (N = 9). Cramps was present in only 6 % of patients (N = 2). This study highlighted the high frequency of non-motor symptoms and extra-cerebellar signs in SCA2. Our findings demonstrate the widespread of nervous system involvement in SCA2 patients and contribute to better understand the natural history of brain degeneration in this genetic condition.

Phonoarticulation in spinocerebellar ataxia type 3

Phonoarticulation is characterized by changes in resonance, diadochokinesis, prosody, sound frequency, vocal quality, and intraoral pressure. The main aim of this study was to characterize the phonoarticulation in spinocerebellar ataxia type 3 (SCA3) and correlate it with clinical and genetic factors. Thirty-one patients with SCA3 who were subjected to spontaneous speech recordings and phonoarticulatory diadochokinesis (DDK) participated in the study. Speech analyses were performed starting after 10 s of spontaneous speech, by three experienced speech therapists, using a protocol for dysarthria adapted from the Mayo Clinic. The intra-evaluator reliability was analyzed. The lower the patient's age at disease onset was, the more frequent the occurrences of monofrequency and altered speech rhythm were. Articulation, DDK, resonance, and prosody showed a moderate correlation with the number of "CAG" triplet repeats. We conclude that the phonoarticulation of patients with Machado-Joseph disease (MJD) is characterized by mixed dysarthrophonia with cerebellar and hypokinetic components, and that there is a tendency toward higher frequency of dysarthrophonia symptoms with lower age of disease onset, longer time since onset and higher number of "CAG" triplet repeats.