Yoshito Sonoda

Mechanism of action of voltage-gated K+ channel antibodies in acquired neuromyotonia.

Acquired neuromyotonia (ANM) is associated with antibodies to voltage‐gated K+ channels (VGKCs). ANM sera reduce the number of K+ currents in neuronal cell lines, but it is not clear how the antibodies act. Here, we show by using the NB‐1 cell line that the reduction in K+ currents by IgG is independent of added complement. IgG Fc and Fab fragments from ANM sera had no effect, but three of four ANM F(ab′)2 fragments significantly reduced K+ currents. Thus, cross‐linking of the channels by divalent antibodies is likely to be an important mechanism in reducing K+ currents. Ann Neurol 2004;56:440–444

Contralateral early blink reflex in patients with HTLV-I associated myelopathy/tropical spastic paraparesis

Thirty-two Japanese patients with HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP) were studied by means of the electrically elicited blink reflex and three responses (R1, R2, R3) were registered. 69% of the patients displayed a uni- or bilateral crossed R1 response (R1k) as compared to 11% in the control group. A positive correlation between R1k and an exaggerated jaw jerk reflex was found in the patients. Central abnormalities of the nervous system with diminished presynaptic inhibition acting in the interneuronal input of the brainstem of HAM/TSP patients was the most likely cause. It could lead to the unmasking of crossed trigemino-facial pathway reflex which is present in the normal population from birth. These results strongly support the supraspinal involvement of the central nervous system (CNS) in HAM/TSP more than usually thought.

Polyneuropathy with minifascicle formation in a patient with 46XY mixed gonadal dysgenesis

Abstract A patient with mixed gonadal dysgenesis showed glove and stocking-type sensory impairment and slowing of motor and sensory nerve conduction. Sural nerve biopsy revealed minifascicular formation with decreased density of myelinated fibers. As far as we are aware, this is the first report of polyneuropathy with minifascicular formation in 46XY mixed gonadal dysgenesis.

The characteristics of camptocormia in patients with Parkinson's disease: A large cross-sectional multicenter study in Japan

PURPOSE The goal of the present study was to clarify the clinical characteristics and laboratory results of parkinsonian symptoms among patients with and without camptocormia. METHODS Seventy-eight Parkinsons disease (PD) patients with camptocormia and 78 PD patients without camptocormia underwent a neurological examination, a blood test, and spinal magnetic resonance imaging (MRI). PD with camptocormia group and PD with non-camptocormia group were matched on age, age at PD onset, and sex. PRINCIPAL RESULTS Camptocormia group had significantly higher prevalence of compression fractures, more severe parkinsonian symptoms, and a greater incidence of dementia than those without camptocormia. Serum creatine kinase levels in camptocormia group significantly elevated compared with non-camptocormia group. There were higher prevalence of abnormal findings in spine MRI including compression fractures and paravertebral muscle changes in camptocormia group compared with non-camptocormia group. MAJOR CONCLUSIONS Camptocormia is associated with a greater prevalence of compression fractures and associated with greater UPDRS part II, part III score, axial score, and lower MMSE in this cross-sectional study. Thus, it can be concluded that camptocormia in PD is predominantly myopathic.

IgM-containing fraction suppressed voltage-gated potassium channels in acquired neuromyotonia

Objectives –  Acquired neuromyotonia (ANM) is an autoimmune disorder caused by antibodies to voltage‐gated potassium channels (VGKC). Previously, we reported a patient with immunoglobulin M (IgM), instead of immunoglobulin G (IgG), anti‐VGKC antibody. The purpose of this study was to determine the function of IgM‐containing fraction in ANM patients.