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BackgroundHirayama disease (HD), amyotrophic lateral sclerosis (ALS) or cervical spondylotic amyotrophy (CSA) may result in atrophy of intrinsic hand and forearm muscles. The incidence of HD is low, and it is rarely encountered in the clinical setting. Consequently, HD is often misdiagnosed as ALS or CSA. It is important to differentiate these diseases because HD is caused by a benign focal lesion that is limited to the upper limbs.MethodsThe thenar and hypothenar compound muscle action potential (CMAP) amplitude of the upper limbs of 100 HD, 97 ALS and 32 CSA cases were reviewed; 35 healthy individuals were included as controls. Seventy-eight percent, 38% and 69% of patients with HD, ALS or CSA had unilateral involvement; the remaining patients were affected bilaterally. Thenar and hypothenar CMAP amplitude evoked by ulnar stimulation was compared with CMAP evoked by median stimulation.ResultsThe ulnar/median CMAP ratio was found to be lower in HD (0.55 ± 0.41, P < 0.0001), higher in ALS (2.28 ± 1.15, P < 0.0001) and no different in CSA (1.21 ± 0.53, P > 0.05) compared with the normal range from previous studies (0.89-1.60) and with the healthy controls (1.15 ± 0.23). Conduction velocities of the sensory and motor nerves, the amplitude of the sensory nerve action potential, and the CMAP amplitude of the unaffected limb were all normal.ConclusionsThe hand muscles were differentially affected between patients with HD, ALS and CSA. The ulnar/median CMAP ratio could be used to distinguish these three diseases.

Abstract.A poor nutritional supply to the cells of the avascular intervertebral discs, caused by dehydration of the extracellular matrix, is a major cause of intervertebral disc degeneration (IDD). Since hepatocyte growth factor (HGF) has been shown to exert antifibrotic effects, we hypothesized that HGF treatment may be capable of retarding IDD. The present study aimed to evaluate the efficacy of HGF treatment in retarding IDD in a rat tail model of disc degeneration. The disc degeneration models were induced by needle puncture of the rat tail discs. Four weeks following needle puncture, a triblock poly(lactide-co-glycolide)-poly(ethyleneglycol)-poly(lactide-co-glycolide; PLGA-PEG-PLGA) polymer gel loaded with HGF or the gel alone was injected into rat tail discs. The efficacy of HGF in retarding IDD was assessed by magnetic resonance imaging (MRI), histological and immunohistochemical evaluation of the type I collagen, type II collagen and bone morphogenetic protein-2 (BMP-2) expression levels. Following injection of the HGF-loaded gel into the nucleus pulposus (NP), a significant trend towards an increase in T2 signal intensity (P=0.028), type II collagen staining in the NP and the number of BMP-2-positive cells in the annulus fibrosus was observed. In addition, the results demonstrated a significant trend towards a decrease in the histological score (P=0.025) and type I collagen staining in the NP compared with segments treated with the gel alone, following the induction of disc degeneration by stab injury. Following treatment with HGF, a tendency for the level of disc height to be maintained was also observed (no statistical significance). By MRI, histological and immunohistochemical evaluation, the present study demonstrated that HGF-loaded PLGA-PEG-PLGA gel was able to retard disc degeneration when injected into the degenerative discs of rat tail models.