ABSTRACT
OBJECTIVE: Preferential wasting of the thenar muscles, the split-hand sign, may be used for early diagnosis of amyotrophic lateral sclerosis (ALS). METHODS: Electronic databases were searched for studies assessing the split-hand index (SHI) and the compound muscle action potential (CMAP) amplitudes of abductor pollicis brevis (APB), first dorsal interosseous (FDI), and abductor digiti minimi (ADM). The SHI was obtained by multiplying CMAP amplitudes of APB and FDI and dividing the product by the CMAP amplitude of ADM. The Bayesian analysis was used for validation. RESULTS: In total, 17 studies and 1635 patients were included. Our meta-analysis revealed that ALS patients had significantly decreased SHI (standardized mean difference [SMD], -1.60, P < 0.001), CMAP of the APB (SMD, -1.67, P < 0.001), FDI (SMD, -1.12, P < 0.001), and ADM (SMD, -1.09, P < 0.001). The binormal receiver operating characteristic curve analysis showed a threshold of < 7.4 for SHI, and cutoff values of < 6.4 mV for APB and < 8.4 mV for FDI, respectively. The Bayesian analysis validated decreased SHI in ALS patients (posterior mean difference of - 5.91). CONCLUSIONS: An SHI of < 7.4 can be used facilitating earlier diagnosis of ALS. SIGNIFICANCE: SHI can be used as a standard neurophysiological biomarker for early diagnosis.
Subject(s)
Amyotrophic Lateral Sclerosis , Amyotrophic Lateral Sclerosis/diagnosis , Bayes Theorem , Hand , Humans , Muscle, Skeletal , ROC CurveABSTRACT
Amyotrophic lateral sclerosis (ALS) is the most common motor neuron disease and has emerged among the disorders with the largest increasing incidence in Western countries. Although the diagnosis is based on clinical grounds, electromyography (EMG), and nerve conduction studies (NCS) play a crucial role to exclude other potential etiologies of lower motor neuron (LMN) dysfunction. Based on clinical grounds, a peculiar pattern of dissociated atrophy of the intrinsic hand and foot muscles, termed the "split-hand" (SH) and "split-leg" (SL) signs, has been described in a significant proportion of subjects with ALS, even at the early stages of the disease, when symptoms are focal. These signs are rare in neurological and non-neurological diseases other than ALS. In this review, we discussed current evidences concerning SH and SL signs, their pathogenetic hypotheses and neurophysiological findings. We also analyze whether SH and SL signs can be reliable markers in the differential diagnosis and in the prognosis of ALS.
ABSTRACT
Objective To investigate the diagnostic value of the split-hand sign in amyotrophic lateral sclerosis ( ALS).Methods Ninety ALS patients, 41 patients with other neuromuscular disorders and 71 normal controls were recruited for conventional nerve conduction study.Compound muscle action potential ( CMAP) amplitude recorded from abductor pollicis brevis ( APB) , abductor digiti minimi ( ADM) and first dorsal interosseous (FDI), CMAP amplitude ratios, CMAP amplitude differences and split-hand index ( SI) were analyzed.Results The APB/ADM CMAP amplitude ratio was significantly lower in the ALS patients (0.44(0.44)) than that in the patients with other neuromuscular disorders (1.31(0.87);z=6.967, P<0.01) and the normal controls (0.99(0.42);z=7.687, P<0.01).The FDI/ADM CMAP amplitude ratio was significantly decreased in the ALS patients ( 0.79 ( 0.46 ) ) compared with that in the normal controls ( 1.23 ( 0.39 ); z =5.899, P <0.01 ).The FDI/ADM CMAP amplitude ratio was comparable between the ALS patients and the patients with other neuromuscular disorders ( 0.93 ( 0.62 );z=1.737,P=0.081).SI was significantly lower in the ALS patients (2.42 (3.14)) than that in the patients with other neuromuscular disorders (10.10(6.54);q=7.947, P<0.05) and the normal controls (17.93(8.32);q=10.827, P<0.05).SI <5.2 can help differentiate ALS from mimic disorders, with a sensitivity of 83.33% and specificity of 96.43%.Conclusions The split-hand sign appears to be a specific feature of ALS.SI robustly differentiates ALS from mimic disorders and potentially facilitates an earlier diagnosis of ALS.
ABSTRACT
Amyotrophic Lateral sclerosis (ALS) is a disease characterized by pure motor asymmetric wasting of various muscles with associated upper motor neuron signs. The split hand sign, which is because of dissociated muscle weakness in the hands (thenar muscles disproportionately wasted as compared to the hypothenar muscles) is a useful clinical sign for bed side diagnosis of ALS.
