BackgroundMotor Unit Number Index (MUNIX) is a neurophysiological measure that provides an index of the number of lower motor neurons in a muscle. Its performance across centres in healthy subjects and patients with Amyotrophic Lateral Sclerosis (ALS) has been established, but inter-rater variability between multiple raters in one single subject has not been investigated.ObjectiveTo assess reliability in a set of 6 muscles in a single subject among 12 examiners (6 experienced with MUNIX, 6 less experienced) and to determine variables associated with variability of measurements.MethodsTwelve raters applied MUNIX in six different muscles (abductor pollicis brevis (APB), abductor digiti minimi (ADM), biceps brachii (BB), tibialis anterior (TA), extensor dig. brevis (EDB), abductor hallucis (AH)) twice in one single volunteer on consecutive days. All raters visited at least one training course prior to measurements. Intra- and inter-rater variability as determined by the coefficient of variation (COV) between different raters and their levels of experience with MUNIX were compared.ResultsMean intra-rater COV of MUNIX was 14.0% (±6.4) ranging from 5.8 (APB) to 30.3% (EDB). Mean inter-rater COV was 18.1 (±5.4) ranging from 8.0 (BB) to 31.7 (AH). No significant differences of variability between experienced and less experienced raters were detected.ConclusionWe provide evidence that quality control for neurophysiological methods can be performed with similar standards as in laboratory medicine. Intra- and inter-rater variability of MUNIX is muscle-dependent and mainly below 20%. Experienced neurophysiologists can easily adopt MUNIX and adequate teaching ensures reliable utilization of this method.

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The aim of our study was to analyze EEG changes in patients with Alzheimer disease (AD) and to determine how closely EEG reflects the progression of mental impairment in people with AD. Ninety-five patients with probable AD according to National Institute of Neurological and Communicative Disorders and Stroke/Alzheimer's Disease and Related Disorders Association criteria treated in our Clinic for Memory Disorders were selected for this study. Patients were divided into three subgroups with mild, marked, and severe dementia according to the results of psychometric scales. The EEG findings were classified using an eight-degree scale according to the background activity, presence and amount of theta and delta waves, focal changes, lateralization of focal changes, synchronization, and presence of sharp and spike waves. A significant correlation between the degree of EEG abnormalities and cognitive impairment was found. We did not observe any correlation between the presence of delta waves and the results of neuropsychological tests. Our study revealed an important diagnostic value of EEG in the estimation of the severity of dementia parallel to psychometric scales.

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The aims were to assess dysautonomia in Alzheimer's Disease (AD), clinically and electrophysiologically, using sympathetic skin response (SSR) test and R-R interval variation (RRIV) test and to analyze the relationship between symptoms of dysautonomia and SSR/RRIV results. A tota of 54 patients with AD and 37 controls were evaluated using Autonomic Symptoms Questionnaire and SSR/RRIV test. Clinical dysautonomia was observed in 66% of patients (eg, orthostatic hypotension in 34.5%, constipation in 17.2%, urinary incontinence in 13.8%). The SSR test was abnormal in 26%, but the RRIV test was abnormal in 97.7% of cases; there was significant difference in RRIV test results between AD and controls (R mean 8.05% and 14.6%, respectively). In AD, clinical dysautonomia occurs at a various degree, and the abnormal SSR and RRIV test results were not always related to the presence of clinical dysautonomia; this observation points that the tests could be used as a useful tool in the assessment of subclinical dysautonomia.

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The aim of our study was to assess the usefulness of the MUNIX method in reflecting the clinical dysfunction in patients with amyotrophic lateral sclerosis (ALS), as well as to assess an intra-rater reproducibility of MUNIX. The study group consisted of a total of 15 ALS patients. The mean age of symptoms onset was 55 years, and the mean disease duration was 10 months. The muscle strength and patients’ functional status were assessed according to the Medical Research Council (MRC) and by ALS functional rating scale revised (ALSFRS-R), respectively. The MUNIX was performed in 6 muscles: abductor pollicis brevis (APB), abductor digiti minimi (ADM), biceps brachii (BB), tibial anterior (TA), extensor digitorum brevis (EDB), and abductor hallucis (AH), unilaterally, at a less affected side. Both muscle-specific and global MRC and MUNIX scores were calculated. In 11 patients, the study protocol was repeated at least twice every 3 months. An additional testing of the intra-rater reliability was performed at the first visit.There were no significant differences between MUNIX test and re-test values in the APB, ADM, BB, TA, EDB, and AH muscles (P >0.05). The highest variability of the test–retest values was found in the BB muscle (7.53%). Although there was a significant test–retest difference in the global MUNIX score (P = 0.02), the variability of the results was as low as 1.26%. The MUNIX value correlated with the muscle-specific MRC score in ABP, ADM, TA, EDB and AH (P <0.05), and the global MUNIX values correlated with global MRC scores (P <0.05). There was also a significant correlation between the global MUNIX score and the clinical dysfunction measured by the ALSFRS-R scale (P <0.05). The global MUNIX showed a higher monthly decline (4.3%) as compared with ALFRS-R (0.7%) and the MRC global score (0.5%).This study confirms that the MUNIX method is a sensitive, reliable, and accurate tool reflecting both motor dysfunction and disease progression in ALS. We have found this approach to be more reliable and technically easier in distal muscles with less atrophy and a better strength.

The Awaji criteria, recently introduced to increase diagnosis sensitivity in amyotrophic lateral sclerosis (ALS), equate the diagnostic significance of neurogenic electrophysiological changes to clinical signs of lower motor neuron dysfunction. They also increase the electrophysiological significance of fasciculation potentials (FPs). The aim of our study was to analyse whether the new parameters improve diagnostic sensitivity in ALS patients primarily diagnosed with the El Escorial criteria. Medical and electrophysiological records of 135 consecutive patients with ALS and 25 patients with progressive muscular atrophy (PMA) who underwent electrophysiological examination of at least three anatomical regions were analysed retrospectively. Results showed that implementation of the Awaji criteria increased the level of ALS diagnosis sensitivity in 5.9% of cases - 1.5% due to the new role of FPs potentials and 4.4% because of equalization of clinical and EMG findings. In 4% of patients the ALS diagnosis was, however, changed from laboratory-supported probable ALS to possible ALS. In conclusion, our study confirms that Awaji modifications are able to improve the diagnostic certainty in a few ALS cases. Although the new approach to FPs markedly increases the number of involved muscles, it only slightly raises the number of involved regions.