The relationship between muscle strength, creatine kinase and electromyography in lipid storage myopathy / 中华神经科杂志

ABSTRACT

Objective To assess the relationship between muscle strength , creatine kinase ( CK) and electromyography ( EMG) in patients with lipid storage myopathy ( LSM).Methods Motor and sensory nerve conduction study, F wave, and quantity EMG were performed in 30 patients with LSM.Muscle strength and CK were studied before EMG.The relationship between EMG , muscle strength and CK were analyzed.Results EMG showed myopathic changes in 19 patients,myopathic coexistence with neuropathic changes in five , and neuropathic changes in two.Four patients had normal EMG.Motor nerve conduction studies showed decreased compound muscle action potential amplitude in seven nerves of two patients , while abnormal sensory nerve conduction in 16 nerves of five patients.Quantity EMG was performed in 78 muscles.Thirty-eight muscles of 21 patients had decreased amplitude and short duration motor unit potential ( MUP) , 6 muscles of 2 patients had increased amplitude and long duration MUP , and 30 muscles of 16 patients had normal MUP.Abnormal spontaneous activities ( SA) were detected in 16 muscles.The M( Q25 , Q75 ) of serum CK was 295.5 (201.0, 4 845.8) U/L in patients with abnormal SA in EMG , and 482.0 (292.8, 963.8) U/L in patients without abnormal SA in EMG (Z=0.281, P=0.778).Medical Research Council ( MRC) Scale in deltoid muscle was 4.3 ±0.7 in muscles with SA and 4.1 ±0.8 in muscles without SA (t=0.490, P=0.628), and that in quadriceps femoris was 3.9 ±0.6 for muscles with SA and 3.7 ± 0.6 for muscles without SA ( t =0.725 , P =0.474 ).MRC Scale in deltoid muscle was 4.1 ±0.7 in muscles with myogenic MUP and 4.1 ±0.9 in muscles without myogenic MUP ( t=0.101, P=0.920), which in quadriceps femoris was 3.8 ±0.6 for muscles with myogenic MUP and 3.7 ±0.7 for muscles without myogenic MUP ( t=0.368 , P=0.716 ).Conclusions Neurogenic or normal MUP and abnormal sensory nerve conduction can be presented in some patients with LSM , while SA is not common.The changes in MUP and SA are neither correlated with CK nor with muscle strength.