[Show abstract][Hide abstract] ABSTRACT: Motor Unit Number Index (MUNIX) is a novel neurophysiological measure that provides an index of the number of functional lower motor neurons in a given muscle. So far its performance across centres in patients with amyotrophic lateral sclerosis (ALS) has not been investigated.
To perform longitudinal MUNIX recordings in a set of muscles in a multicentre setting in order to evaluate its value as a marker of disease progression.
Three centres applied MUNIX in 51 ALS patients over 15 months. Six different muscles (abductor pollicis brevis, abductor digiti minimi, biceps brachii, tibialis anterior, extensor dig. brevis, abductor hallucis) were measured every 3 months on the less affected side. The decline between MUNIX and ALSFRS-R was compared.
31 participants reached month 12. For all participants, ALSFRS-R declined at a rate of 2.3%/month. Using the total score of all muscles, MUNIX declined significantly faster by 3.2%/month (p≤0.02). MUNIX in individual muscles declined between 2.4% and 4.2%, which differed from ASLFRS-R decline starting from month 3 (p≤0.05 to 0.002). Subgroups with bulbar, lower and upper limb onset showed different decline rates of ALSFRS-R between 1.9% and 2.8%/month, while MUNIX total scores showed similar decline rates over all subgroups. Mean intraclass correlation coefficient for MUNIX intra-rater reliability was 0.89 and for inter-rater reliability 0.80.
Conclusion: MUNIX is a reliable electrophysiological biomarker to track lower motor neuron loss in ALS.
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No preview · Article · May 2015 · Journal of neurology, neurosurgery, and psychiatry
[Show abstract][Hide abstract] ABSTRACT: Introduction:
Transthyretin familial amyloid polyneuropathy (TTR-FAP) is characterized by early selective involvement of small nerve fibers. Initial clinical diagnosis is complicated by psychosocial factors. We evaluated diagnostic accuracy of sural sensory nerve action potentials, plantar sympathetic skin response (SSR), and cortical laser-evoked potentials (LEP) to dorsal foot stimulation in the early diagnosis of TTR-FAP.
Sixty-three subjects with TTR-FAP (Val30Met) mutation were split into 2 groups (asymptomatic carriers and early-symptomatic patients) and compared with 33 healthy controls.
The diagnostic accuracy of plantar SSR amplitude and LEP N2 latency was similar; all had very high specificity (94 to 97%) but low sensitivity (22 to 32%) in distinguishing controls from carriers and early-symptomatic patients. No control had abnormal results on both tests.
Plantar SSR and LEPs have similar diagnostic performance in detecting small-fiber dysfunction in early TTR-FAP; we propose that both tests should be used to investigate this population. Muscle Nerve 49: 181-186, 2014.
[Show abstract][Hide abstract] ABSTRACT: To investigate the intra-rater and inter-rater test-retest reliability of the Motor Unit Number Index (MUNIX) in healthy subjects in a multicentre setting.
Six study centres applied the MUNIX technique in 66 healthy subjects. Five to six muscles (biceps brachii, BB; abductor digiti minimi, ADM; abductor pollicis brevis, APB; tibialis anterior, TA; extensor digitorum brevis, EDB and abductor hallucis, AH) were measured in each volunteer four times by two independent examiners.
The method was easy to perform and well tolerated. The intraclass correlation coefficient (ICC) varied between centres and muscles. Intra-rater reliability was greatest for the AH (ICC 0.83) and EDB (ICC 0.81). Inter-rater reliability was greatest for the AH (ICC 0.69) and ADM muscles (ICC 0.69). The most critical muscle was the APB muscle (ICC 0.52, total variability). This was mostly due to variability in the compound muscle action potential (CMAP) measurements. MUNIX values of the APB, ADM and TA fell into the same range as in other motor unit number estimation (MUNE) studies.
MUNIX measurements in multiple muscles show good inter- and intra-rater reliability in healthy subjects. CMAP amplitude must be controlled to optimize reliability.
Results suggest that MUNIX could serve as a reliable marker for motor neuron loss in diseases like amyotrophic lateral sclerosis.
Full-text · Article · Mar 2011 · Clinical neurophysiology: official journal of the International Federation of Clinical Neurophysiology
[Show abstract][Hide abstract] ABSTRACT: Familial amyloid polyneuropathy (FAP) is a progressive neuropathy with autonomic dysfunction. Domino liver transplantation (DLT), in which the liver of an FAP patient is transplanted into another patient, is routinely applied to compensate for the shortage of available organs. We report a patient who developed a clinical picture of FAP 9 years after a DLT from an FAP donor. Electrophysiological, neuropathological, and autonomic tests were administered. The patient presented with typical clinical features of FAP. Electrophysiological investigation confirmed a moderate sensorimotor axonal and autonomic neuropathy. Sural nerve biopsy confirmed the presence of amyloid deposits in the endoneurium. Skin biopsy at the ankle showed reduced intraepidermal nerve fiber density. Our report shows that FAP can develop in a recipient of an FAP liver. This suggests that careful longitudinal study is required to evaluate the risk of FAP polyneuropathy in patients who undergo domino liver transplantation. Muscle Nerve, 2010