First, the delay from onset of the disease to diagnosis of ALS can vary between 13 and 18 months 6, 7 and the diagnostic delay may even be greater in patients who present with isolated LMN signs. 4, 5 In ALS, the absence of a disease marker for UMN and LMN involvement has 2 main negative consequences. Paraclinical and laboratory tests are used only to exclude “ALS-mimic” syndromes. 3ĭespite technical advances in medicine in the last century, the diagnosis of sporadic ALS relies on the interpretation of clinical symptoms and signs (ie, signs suggestive of combined UMN and LMN degeneration, together with disease progression compatible with a neurodegenerative disorder). 2 To date, the only specific marker of sporadic ALS is the presence of inclusions staining positively for ubiquitin and TDP-43 in degenerating motor neurons. 2 Most patients with ALS, however, have no obvious family history and have sporadic ALS. 1 In approximately 5%–10% of patients, the disease is inherited 20% of these individuals have a mutation of the SOD1 gene approximately 2%–5%, of the TARDBP ( TDP-43) gene and 2%–4%, of the FUS/TLS gene. The phenotypic expression of ALS is highly heterogeneous and determined by 4 elements: 1) body region of onset, 2) relative mix of UMN and LMN involvement, 3) rate of progression, and 4) cognitive impairment. Peak ratio interference pattern analysis is largely not helpful in detecting this involvement.Abbreviations ALS amyotrophic lateral sclerosis ALSFRS ALS Functional Rating Scale Cho choline Cr creatine CST corticospinal tract DTI diffusion tensor imaging FA fractional anisotropy FLAIR fluid-attenuated inversion recovery fMRI functional MR imaging FTD frontotemporal dementia FUS/TLS fused in sarcoma/translocated in liposarcoma gene GM gray matter 1H-MR spectroscopy proton MR spectroscopy L left LMN lower motor neuron MD mean diffusivity mIns myo-inositol MT magnetization transfer MTR MT ratio NAA N-acetylaspartate ns not significant PD proton density R right SOD1 superoxide dismutase 1 SPM statistical parametric mapping TDP-43 TAR DNA-binding protein gene UMN upper motor neuron VBM voxel-based morphometry WM white matterĪLS, also known as motor neuron disease, is a neurodegenerative disorder characterized by a progressive muscular paralysis reflecting degeneration of motor neurons in the primary motor cortex, brain stem, and spinal cord. Subclinical bulbar involvement could be detected by quantitative MUAP analysis in six ALS patients without clinical bulbar signs, and by peak ratio interference pattern analysis in two.Ĭonventional needle EMG of the fifth, seventh, and eleventh cranial nerve innervated muscles shows subclinical bulbar involvement quite frequently. If a result of either EMG technique was neuropathic in at least one of the three investigated muscles, bulbar involvement was assumed. Peak ratio interference pattern analysis was interpreted as neuropathic if the peak ratio, the number of small time intervals, or both were below the mean (-2 SD). Quantitative MUAP analysis was interpreted as neuropathic if MUAP duration, MUAP amplitude, or both exceeded the mean (+2 SD). The normal mean (2 SD) peak ratio of the frontalis was 2.3 (1.1) milliseconds masseter, 1.2 (0.4) milliseconds and sternocleidomastoideus, 1.5 (0.7) milliseconds. The normal mean (2 SD) MUAP duration of the frontalis muscle was 7.4 (2.2) milliseconds masseter muscle, 9.3 (3.1) milliseconds and sternocleidomastoideus muscle, 10.9 (4.1) milliseconds. With both electromyographic (EMG) techniques, electrical activity was recorded via needle electrodes from the right frontalis, masseter, and sternocleidomastoideus muscles of nine ALS patients without clinical bulbar signs (Frenchay score >85%) aged 40 to 87 years 21 healthy subjects aged 27 to 74 years and five ALS patients with clinical bulbar signs (Frenchay score <85%) aged 53 to 69 years. To determine if quantitative motor unit action potential (MUAP) analysis and peak ratio interference pattern analysis of the fifth, seventh, and eleventh cranial nerve innervated muscles are helpful in the assessment of subclinical bulbar involvement in ALS.
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