Yumiko Arimura

The clinical and pathological features of peripheral neuropathy accompanied with HTLV-I associated myelopathy

We describe the clinical and pathological studies in HTLV-I associated myelopathy (HAM)/tropical spastic paraparesis (TSP) patients with peripheral neuropathy as proven by sural nerve biopsy. Sural nerve pathology in HAM/TSP patients revealed that the most common type of pathologic change is a combination of both demyelination and remyelination and axonal degeneration and regeneration, and this change is modified by the complications. The pathologic changes were correlated with neither the duration of disease nor human T lymphotropic virus type I (HTLV-I) proviral load. This study suggests that peripheral nerves could be involved in HAM/TSP.

Reference values for voluntary and stimulated single-fibre EMG using concentric needle electrodes: A multicentre prospective study

OBJECTIVE The aim of this study is to establish reference values for single-fibre electromyography (SFEMG) using concentric needles in a prospective, multicentre study. METHODS Voluntary or stimulated SFEMG at the extensor digitorum communis (EDC) or frontalis (FRO) muscles was conducted in 56-63 of a total of 69 normal subjects below the age of 60years at six Japanese institutes. The cut-off values for mean consecutive difference (MCD) of individual potentials were calculated using +2.5 SD or 95% prediction limit (one-tail) of the upper 10th percentile MCD value for individual subjects. RESULTS The cut-off values for individual MCD (+2.5 SD) were 56.8μs for EDC-V (voluntary SFEMG for EDC), 58.8μs for EDC-S (stimulated SFEMG for EDC), 56.8μs for FRO-V (voluntary SFEMG for FRO) and 51.0μs for FRO-S (stimulated SFEMG for FRO). The false positive rates using these cut-off values were around 2%. CONCLUSIONS The +2.5 SD and 95% prediction limit might be two optimal cut-off values, depending on the clinical question. The obtained reference values were larger than those reported previously using concentric needles, but might better coincide with conventional values. SIGNIFICANCE This is the first multicentre study reporting reference values for SFEMG using concentric needles. The way to determine cut-off values and the statistically correct definition of the percentile were discussed.

Intraepidermal nerve fiber density and nerve conduction study parameters correlate with clinical staging of diabetic polyneuropathy

AIM AND METHODS To assess the usefulness of the diagnostic and staging criteria for diabetic polyneuropathy (DP) by the Diabetic Neuropathy Study Group in Japan (DNSGJ) we examined clinical features, intraepidermal nerve fiber densities (IENFD) and nerve conduction studies (NCS) and coefficient of variation of the R-R intervals (CVR-R) in 44 patients with diabetes. RESULTS The patients were classified into stage I (n=20), II (n=6), III+IV (n=12), and V (n=6) according to the staging criteria by DNSGJ. IENFD decreased as stages progressed (13.8±7.1 fiber/mm in stage I to 0.8±1.3 fiber/mm in stage V). Compound motor and sensory action potential and motor and sensory nerve conduction velocity decreased with progressing stage. F-wave latency prolonged as stages progressed. CVR-R decreased with progressing stage (4.41%±2.65% in stage I to 1.33%±0.57% in stage V). IENFD correlated with the various parameters of NCS (r=0.378-0.636, p<0.05) and CVR-R (r=0.399, p=0.007). CONCLUSIONS Clinical staging for DP by DNSGJ reflects the results of small and large fiber neuropathy.

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.

Study of lower limb somatosensory evoked potentials in 96 cases of HTLV-I-associated myelopathy/tropical spastic paraparesis.

Lower limb somatosensory evoked potentials (LSEPs) were performed along with neurological evaluation in 96 HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP) patients. The N20 latencies were abnormal in 5 cases. Central sensory conduction time (CSCT) was abnormal in 42 cases. A highly significant correlation (p < 0.001, r = 0.418) was found between CSCT and disability score. Such a correlation was not found between CSCT and other clinical findings, onset of illness, illness duration, serum and CSF antibody titer to HTLV-I and vibratory sensation. There was no difference of the mean of CSCT between the cases with sensory impairment and those without it. This shows that LSEPs are useful to estimate the disability of HAM/TSP. Also the cases with delayed CSCT and normal sensation suggest that LSEPs are capable of detecting subclinical lesions of the spinal cord in HAM/TSP.

Neuro-ophthalmological abnormalities in HTLV-I associated myelopathy

To determine whether neuro-ophthalmological abnormality exists in HTLV-I Associated Myelopathy (HAM), 22 patients were examined using electrooculography and visual evoked potentials and compared with controls. Eleven cases had mild abnormalities in smooth pursuit movements. Of these 11 patients, four had transient diplopia or jerky eye movements. One patient had a delayed P100 latency in the visual evoked potentials. These data suggest that the central nervous system may also be involved in HAM.

The origin of spontaneous discharges in acquired neuromyotonia. A Macro EMG study

OBJECTIVE To study the generator sites of spontaneous discharges in patients with immune-mediated neuromyotonia. METHODS Macro EMGs triggered by both spontaneously and voluntarily activated single action potentials were recorded and the mean peak-to-peak amplitude and area of the macro motor unit potentials were compared in two patients with typical acquired neuromyotonia having positive antibodies against voltage-gated potassium channels. RESULTS Mean peak-to-peak amplitude and area of Macro EMG motor unit potentials (macro MUPs) triggered by spontaneous discharges were significantly smaller than those triggered by voluntary activation in both patients. However, a few macro MUPs triggered by spontaneous discharges resembled those triggered by voluntary activation. CONCLUSIONS Spontaneous discharges in two patients with immune-mediated neuromyotonia seem to be mostly generated at sites distal to the terminal axon branching points. SIGNIFICANCE This finding may provide a new insight in the understanding of spontaneous discharges in immune-mediated neuromyotonia.

Posterior interosseous nerve syndrome with hourglass-like fascicular constriction of the nerve

We describe a case of the posterior interosseous nerve (PIN) syndrome in a patient with gout. Exploration of the PIN revealed multiple hourglass-like constriction of the PIN, which did not correspond to any extrinsic compressing structures. Hourglass-like constrictions of the PIN is one of the causes of the painful PIN syndrome.

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.

Muscle membrane excitability after exercise in thyrotoxic periodic paralysis and thyrotoxicosis without periodic paralysis.

We evaluated whether the paralytic attacks in thyrotoxic periodic paralysis (TPP) are primarily due to the abnormal excitability of the muscle membrane caused by a preexisting latent abnormality or to the effects of thyroid hormone. The prolonged exercise (PE) test was used to evaluate muscle membrane excitability in 21 patients with TPP and 11 patients with thyrotoxicosis without paralytic attacks (Tw/oPP) in the hyperthyroid state. The PE tests were compared between the hyperthyroid and euthyroid states in five of the TPP and three of the Tw/oPP patients. Compared to 20 healthy subjects, a significant increase in compound muscle action potential (CMAP) amplitudes immediately after exercise and a significant time‐dependent gradual decline in CMAP amplitudes starting from 20 min after exercise were observed in the TPP patients. A significant decline in CMAP amplitudes was also observed in the Tw/oPP patients but only at 50 min after exercise. All of the TPP and Tw/oPP patients had a tendency to improve in the euthyroid state; the PE tests remained abnormal only in the TPP patients. Paralytic attacks in TPP patients are due primarily to a preexisting latent abnormal excitability of the muscle membrane, possibly genetic in origin. Muscle Nerve, 2007