Pattern Differences of Small Hand Muscle Atrophy in Amyotrophic Lateral Sclerosis and Mimic Disorders

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Abstract

Background:

Amyotrophic lateral sclerosis (ALS) and some mimic disorders, such as distal-type cervical spondylotic amyotrophy (CSA), Hirayama disease (HD), and spinobulbar muscular atrophy (SBMA) may present with intrinsic hand muscle atrophy. This study aimed to investigate different patterns of small hand muscle involvement in ALS and some mimic disorders.

Methods:

We compared the abductor digiti minimi/abductor pollicis brevis (ADM/APB) compound muscle action potential (CMAP) ratios between 200 ALS patients, 95 patients with distal-type CSA, 88 HD patients, 43 SBMA patients, and 150 normal controls.

Results:

The ADM/APB CMAP amplitude ratio was significantly higher in the ALS patients ( P < 0.001) than that in the normal controls. The ADM/APB CMAP amplitude ratio was significantly reduced in the patients with distal-type CSA ( P < 0.001) and the HD patients ( P < 0.001) compared with that in the normal controls. The patients with distal-type CSA had significantly lower APB CMAP amplitude than the HD patients ( P = 0.004). The ADM/APB CMAP amplitude ratio was significantly lower in the HD patients ( P < 0.001) than that in the patients with distal-type CSA. The ADM/APB CMAP amplitude ratio of the SBMA patients was similar to that of the normal controls ( P = 0.862). An absent APB CMAP and an abnormally high ADM/APB CMAP amplitude ratio (≥4.5) were observed exclusively in the ALS patients.

Conclusions:

The different patterns of small hand muscle atrophy between the ALS patients and the patients with mimic disorders presumably reflect distinct pathophysiological mechanisms underlying different disorders, and may aid in distinguishing between ALS and mimic disorders.

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Most cited references 28

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Altered axonal excitability properties in amyotrophic lateral sclerosis: impaired potassium channel function related to disease stage.

Setsu Sawai, K Ogawara, Telma Nakata … (2006)

Fasciculations are a characteristic feature of amyotrophic lateral sclerosis (ALS), and can arise proximally or distally in the motor neuron, indicating a widespread disturbance in membrane excitability. Previous studies of axonal excitability properties (i.e. threshold electrotonus, strength-duration time constant) have suggested respectively that change in potassium or sodium channels may be involved. To reinvestigate these changes and explore their correlation with disease stage, multiple axonal excitability properties (threshold electrotonus, strength-duration time constant, recovery cycle and current-threshold relationship) were measured for the median nerve at the wrist in 58 ALS patients, and compared with 25 age-matched controls. In ALS, there were greater changes in depolarizing threshold electrotonus (i.e. less accommodation) (P 5 mV). Patients with severely reduced CMAP (<1 mV) alone showed reduced threshold changes to hyperpolarizing current. These results suggest a changing pattern of abnormal membrane properties with disease progression. First, persistent Na+ conductance increases, possibly associated with collateral sprouting, and then K(+) conductances decline. Both changes cause axonal hyperexcitability, and may contribute to the generation of fasciculations. These serial changes in axonal properties could provide insights into the pathophysiology of ALS, and implications for future therapeutic options.

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Axonal excitability properties in amyotrophic lateral sclerosis.

Matthew Kiernan, Steve Vucic (2006)

To investigate axolemmal ion channel function in patients diagnosed with sporadic amyotrophic lateral sclerosis (ALS). A recently described threshold tracking protocol was implemented to measure multiple indices of axonal excitability in 26 ALS patients by stimulating the median motor nerve at the wrist. The excitability indices studied included: stimulus-response curve (SR); strength-duration time constant (tauSD); current/threshold relationship; threshold electrotonus to a 100 ms polarizing current; and recovery curves to a supramaximal stimulus. Compound muscle action potential (CMAP) amplitudes were significantly reduced in ALS patients (ALS, 2.84+/-1.17 mV; controls, 8.27+/-1.09 mV, P<0.0005) and the SR curves for both 0.2 and 1 ms pulse widths were shifted in a hyperpolarized direction. Threshold electrotonus revealed a greater threshold change to both depolarizing and hyperpolarizing conditioning stimuli, similar to the 'fanned out' appearance that occurs with membrane hyperpolarization. The tauSD was significantly increased in ALS patients (ALS, 0.50+/-0.03 ms; controls, 0.42+/-0.02 ms, P<0.05). The recovery cycle of excitability following a conditioning supramaximal stimulus revealed increased superexcitability in ALS patients (ALS, 29.63+/-1.25%; controls, 25.11+/-1.01%, P<0.01). Threshold tracking studies revealed changes indicative of widespread dysfunction in axonal ion channel conduction, including increased persistent Na+ channel conduction, and abnormalities of fast paranodal K+ and internodal slow K+ channel function, in ALS patients. An increase in persistent Na+ conductances coupled with reduction in K+ currents would predispose axons of ALS patients to generation of fasciculations and cramps. Axonal excitability studies may provide insight into mechanisms responsible for motor neuron loss in ALS.

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Widespread nuclear and cytoplasmic accumulation of mutant androgen receptor in SBMA patients.

Akira Inukai, Masahisa Katsuno, Yuji Nakagomi … (2005)

Spinal and bulbar muscular atrophy (SBMA) is an inherited adult onset motor neuron disease caused by the expansion of a polyglutamine (polyQ) tract within the androgen receptor (AR), affecting only males. The characteristic pathological finding is nuclear inclusions (NIs) consisting of mutant AR with an expanded polyQ in residual motor neurons, and in certain visceral organs. We immunohistochemically examined 11 SBMA patients at autopsy with 1C2, an antibody that specifically recognizes expanded polyQ. Our study demonstrated that diffuse nuclear accumulation of mutant AR was far more frequent and extensive than NIs being distributed in a wide array of CNS nuclei, and in more visceral organs than thus far believed. Mutant AR accumulation was also present in the cytoplasm, particularly in the Golgi apparatus; nuclear or cytoplasmic predominance of accumulation was tissue specific. Furthermore, the extent of diffuse nuclear accumulation of mutant AR in motor and sensory neurons of the spinal cord was closely related to CAG repeat length. Thus, diffuse nuclear accumulation of mutant AR apparently is a cardinal pathogenetic process underlying neurological manifestations, as in SBMA transgenic mice, while cytoplasmic accumulation may also contribute to SBMA pathophysiology.

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Author and article information

Journal

Journal ID (nlm-ta): Chin Med J (Engl)

Journal ID (iso-abbrev): Chin. Med. J

Journal ID (publisher-id): CMJ

Title: Chinese Medical Journal

Publisher: Medknow Publications & Media Pvt Ltd (India )

ISSN (Print): 0366-6999

Publication date (Print): 05 April 2016

Volume: 129

Issue: 7

Pages: 792-798

Affiliations

[1]Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100730, China

Author notes

Address for correspondence: Dr. Li-Ying Cui, Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100730, China E-Mail: pumchcly@ 123456sina.com

Article

Publisher ID: CMJ-129-792

DOI: 10.4103/0366-6999.178953

PMC ID: 4819298

PubMed ID: 26996473

SO-VID: abf09712-63af-4071-b1bc-a0e7145040d1

License:

This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as the author is credited and the new creations are licensed under the identical terms.

Pattern Differences of Small Hand Muscle Atrophy in Amyotrophic Lateral Sclerosis and Mimic Disorders

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Abstract

Background:

Methods:

Results:

Conclusions:

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Most cited references 28

Altered axonal excitability properties in amyotrophic lateral sclerosis: impaired potassium channel function related to disease stage.

Axonal excitability properties in amyotrophic lateral sclerosis.

Widespread nuclear and cytoplasmic accumulation of mutant androgen receptor in SBMA patients.

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