Literature Review On Motor Neurone Disease - amazonia.fiocruz.br

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In the last 20 years, several modalities of neuromodulation, mainly based on non-invasive brain stimulation NIBS techniques, have been tested as a non-pharmacological therapeutic approach to slow disease progression in amyotrophic lateral sclerosis ALS. In both sporadic and familial ALS cases, neurophysiological studies point to motor cortical hyperexcitability as a possible priming factor in neurodegeneration, likely related to dysfunction of both excitatory and inhibitory mechanisms. A trans-synaptic anterograde mechanism of excitotoxicity is thus postulated, causing upper and lower motor neuron degeneration. Specifically, motor neuron hyperexcitability and hyperactivity are attributed to intrinsic cell abnormalities related to altered ion homeostasis and to impaired glutamate and gamma aminobutyric acid gamma-aminobutyric acid GABA signaling. Several neuropathological mechanisms support excitatory and synaptic dysfunction in ALS; additionally, hyperexcitability seems to drive DNA-binding protein kDA TDP pathology, through the upregulation of unusual isoforms directly contributing to ASL pathophysiology. Corticospinal excitability can be suppressed or enhanced using NIBS techniques, namely, repetitive transcranial magnetic stimulation rTMS and transcranial direct current stimulation tDCS , as well as invasive brain and spinal stimulation. This potential has led to several small trials testing different stimulation interventions to antagonize excitotoxicity in ALS. Overall, these studies suggest a possible efficacy of neuromodulation in determining a slight reduction of disease progression, related to the type, duration, and frequency of treatment, but current evidence remains preliminary. Literature Review On Motor Neurone Disease

Literature Review On Motor Neurone Disease Video

Motor Neurone Disease (ALS or Leu Gehrig's)

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Review ARTICLE

In the latter case, please turn on Javascript support in your web browser and reload this page. The data that support the findings of this study are available from the corresponding author upon reasonable request.

Disproportionate muscle atrophy is a distinct phenomenon in amyotrophic lateral sclerosis ALS ; however, preferentially affected leg muscles remain unknown. We aimed to identify this split-leg phenomenon in ALS and determine its pathophysiology. Our findings help to elucidate the pathophysiology of split-leg phenomenon.

Amyotrophic lateral sclerosis ALS is a catastrophic neurodegenerative disorder affecting the upper motor neurons UMNs and lower motor neurons LMNscharacterized by a relentless progression of skeletal muscle weakness.

Publication types

Unfortunately, there has been no reliable diagnostic biomarker for ALS, and so the early diagnosis is often difficult, especially in those presenting with leg weakness 12. Because FDI and ADM are innervated by the same motor nerve and share an identical myotome, this phenomenon may imply a cortical bias; the larger somatotopic representation for thenar muscles may lead to differential degeneration of anterior horn cells via glutamate excitotoxicity 9 — This idea has been supported by several transcranial magnetic stimulation TMS studies. On the contrary, a few studies suggested primary dysfunction Literature Review On Motor Neurone Disease spinal motor read more or peripheral axons 615 However, this contrasts to clinical experience in which ALS patients sometimes present with foot drop Of relevance, two successive studies that compared extensor digitorum brevis EDB and abductor hallucis AH muscles proposed larger degree of atrophy in the former 19 Nonetheless, these studies did not compare the leg and foot muscles simultaneously nor investigate other forms of motor neuron disease such as progressive muscular atrophy and flail leg syndrome.

Moreover, only one study included an ALS mimic lumbar spondylosis in its analysis, whereas the others compared ALS patients to healthy controls Further, through correlating clinical variables with the split-leg index SIwe tried to gain insight into the underlying pathophysiology. The age distribution https://amazonia.fiocruz.br/scdp/essay/mormon-bank-utah/concert-review-the-concert.php similar between groups ALS: Baseline clinical and electrophysiologic characteristics of the participants in each group.

Associated Data

The SI in each group is represented using box plots in Fig. SI TA : bulbar-onset 0. Distribution of split-leg index according to the onset region. While EDB extends the toes in conjunction with TA-mediated ankle dorsiflexion, AH is Revuew co-activated during plantar flexion of the ankle. Thus, we propose that dorsiflexors of lower limbs in ALS Diwease more heavily affected than plantar flexors. This is in concordance with previous clinical observations that patients with ALS commonly present with foot drop 17 — Notably, the so-called split-leg phenomenon was also present and was even more prominent in PMA. To date, cortical influence is the dominant theory explaining Literature Review On Motor Neurone Disease muscle involvement in ALS. Denser corticospinal input to thenar muscles that facilitates precise hand motions, unique to humans, might lead to premature degeneration. Accordingly, previous studies on split-leg syndrome have suggested a cortical mechanism 1718 Another study using TMS showed exclusive short-interval facilitation in TA compared to gastrocnemius and soleus The above findings indicate that ankle dorsiflexors receive a greater innervation from corticospinal neurons, which also correlates with our results.

Indeed, corticospinal input might considerably differ, even between the nearest muscles. Thus, further analyses Reviiew necessary to fully understand UMN innervations of the lower-limb musculature and to confirm the corticofugal mechanism of split-leg phenomenon 23 — Of note, cortical influences do not fully explain our findings. Accordingly, we propose additional peripheral pathophysiological mechanisms to support these results. In ALS, it is known that lower motor neurons innervating fast-twitching myofibers, with larger soma and higher innervation ratios, are especially prone to degeneration Hence, heterogeneous anterior horn cell-composition within lower limbs might attribute to the uneven atrophy.

In addition, repeated phasic activation of Literathre during locomotion might produce greater oxidative stress in these antigravity muscles, leading to premature dieback 28 Additionally, spinal Literature Review On Motor Neurone Disease or Renshaw cells, which mediate recurrent visit web page of spinal motoneurons exhibit an altered physiologic status in ALS Increased potentiation of the descending medial longitudinal fasciculus following corticospinal tract lesions was reported ]