Spinal and bulbar muscular atrophy (SBMA) is an adult-onset, lower motor neuron disease caused by an aberrant elongation of a CAG repeat in the androgen receptor (AR) gene. The main symptoms are weakness and atrophy of bulbar, facial and limb muscles, but sensory disturbances are frequently found in SBMA patients. Motor symptoms have been attributed to the accumulation of mutant AR in the nucleus of lower motor neurons, which is more profound in patients with a longer CAG repeat. We examined nerve conduction properties including F-waves in a total of 106 patients with genetically confirmed SBMA (mean age at data collection = 53.8 years; range = 31-75 years) and 85 control subjects. Motor conduction velocities (MCV), compound muscle action potentials (CMAP), sensory conduction velocities (SCV) and sensory nerve action potentials (SNAP) were significantly decreased in all nerves examined in the SBMA patients compared with that in the normal controls, indicating that axonal degeneration is the primary process in both motor and sensory nerves. More profound abnormalities were observed in the nerves of the upper limbs than in those of the lower limbs. F-waves in the median nerve were absent in 30 of 106 cases (28.3%), but no cases of absent F-waves were observed in the tibial nerve. From an analysis of the relationship between CMAPs and SNAPs, patients were identified with different electrophysiological phenotypes: motor-dominant, sensory-dominant and non-dominant phenotypes. The CAG repeat size and the age at onset were significantly different among the patients with motor- and sensory-dominant phenotypes, indicating that a longer CAG repeat is more closely linked to the motor-dominant phenotype and a shorter CAG repeat is more closely linked to the sensory-dominant phenotype. Furthermore, when we classified the patients by CAG repeat size, CMAP values showed a tendency to be decreased in patients with a longer CAG repeat (> or =47), while SNAPs were significantly decreased in patients with a shorter CAG repeat (<47). In addition, we found that the frequency of aggregation in the sensory neuron cytoplasm tended to inversely correlate with the CAG repeat size in the autopsy study, supporting the view that the CAG repeat size differentially correlates with motor- and sensory-dominant phenotypes. In conclusion, our results suggest that there are unequivocal electrophysiological phenotypes influenced by CAG repeat size in SBMA.

We examined whether cardiac sympathetic denervation influences the cardiovascular response to exercise in Parkinson's disease (PD). Sixteen patients with PD were divided into two groups, according to their cardiac uptake of (123)I-metaiodobenzylguanidine (denervated group, 10 patients with heart to mediastinum (H/M) ratio < 1.7; innervated group, six patients with H/M ratio > 1.7) and compared changes in blood pressure (BP), heart rate (HR), and cardiac contractility with 13 control subjects during ergometric exercise stress. Velocity index (VI), an indicator of cardiac contractility, was measured using impedance cardiography and recorded every minute. Exercise began at a power output of 20 W for the first 2 min and increased 10 W every 2 min to a maximal intensity of 60 W. All control subjects accomplished the procedure while six patients with PD could not continue after the first minute of 50 W loading. There were no significant differences in BP or HR change between the three groups. However, a significant reduction in VI was observed from the first minute of the 30 W workload in the denervated group compared to the control group. This lowered response continued till 50 W loading and was significantly different to the innervated group at 50 W loading. No significant VI changes were observed between the control and innervated groups throughout the exercise test. Patients with PD with reduced MIBG uptake had a lowered cardiac contractility than innervated subjects during exercise, suggesting that this response represents the impaired exercise capacity of patients with PD with cardiac sympathetic denervation.

The results suggest that MUNE is an electrophysiological parameter that reflects the severity and progression of motor neuron degeneration in patients with SBMA.

This study evaluated pupillary postganglionic autonomic dysfunction and its relationship to visual disturbance in idiopathic Parkinson's disease (PD). Pupillary sensitivity was examined in relation to a parasympathomimetic agent [0.05% pilocarpine hydrochloride (PL)] and to a sympathomimetic agent [0.02% dipivefrine hydrochloride (DPE)] using infrared pupillography in 40 PD patients and 17 age-matched controls. Visual disturbances were evaluated as well, including blurring, photophobia, night blindness and involuntary eyelid closure in response to light. Pupillary supersensitivity to PL and DPE and their relation to visual disturbances were found to be significantly greater in PD patients than in controls (22.3 +/- 15.1 vs. 10.4 +/- 11.4%, P < 0.005, and14.5 +/- 14.5 vs. 4.9 +/- 8.7%, P < 0.01, respectively). In addition, pupillary sympathetic supersensitivity did not correlate with a reduction of 123I-metaiodobenzylguanidine (MIBG) cardiac accumulation. Patients with PD reported more blurred vision (P < 0.001) and involuntary eyelid closure in response to light (P < 0.05) than controls. Patients with supersensitivity to both PL and DPE complained more often of blurred vision than patients without supersensitivity (P < 0.05). Pupillary sensitivity to PL correlated significantly with a summed score for visual disturbance (P < 0.05, r = 0.417), but DPE sensitivity did not. PD patients have both parasympathetic and sympathetic postganglionic impairments affecting the pupil. Our findings demonstrate that parasympathetic dysfunction contributes significantly to visual disturbance in PD.

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