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Neurology
Published in Stephan Strobel, Lewis Spitz, Stephen D. Marks, Great Ormond Street Handbook of Paediatrics, 2019
Fenella Kirkham, Adnan Manzur, Stephanie Robb
SMA type I occurs in 1 in 20,000. It is autosomal recessive, with deletion of exon 7 of the survival motor neuron (SMN) gene on chromosome 5q13 in 95% of cases. Pathologically there is loss of anterior horn cells.
Head, neck and vertebral column
Published in David Heylings, Stephen Carmichael, Samuel Leinster, Janak Saada, Bari M. Logan, Ralph T. Hutchings, McMinn’s Concise Human Anatomy, 2017
David Heylings, Stephen Carmichael, Samuel Leinster, Janak Saada, Bari M. Logan, Ralph T. Hutchings
Upper and lower motor neurons - corticospinal (and corticonuclear) and extrapyramidal fibres constitute the upper motor neurons. Anterior horn cells with their fibres running to skeletal muscles constitute the lower motor neurons. Typical causes of damage to upper motor neurons are birth injury to the brain (cerebral palsy), vascular damage to the internal capsule (stroke, see above), or spinal cord injury that damages the tracts. Polio (anterior poliomyelitis, a virus infection of anterior horn cells) and a severed peripheral nerve are examples of lower motor neuron damage.
Peripheral Nerve Injuries
Published in Louis Solomon, David Warwick, Selvadurai Nayagam, Apley and Solomon's Concise System of Orthopaedics and Trauma, 2014
Louis Solomon, David Warwick, Selvadurai Nayagam
The signal, or action potential, carried by motor neurons is transmitted to the muscle fibres by the release of a chemical transmitter, acetylcholine, at the terminal bouton of the nerve. Sensory signals are similarly conveyed to the dorsal root ganglia and from there up the ipsilateral column of the spinal cord, through the brainstem and thalamus, to the opposite (sensory) cortex. Proprioceptive impulses from the muscle spindles and joints bypass this route and are carried to the anterior horn cells as part of a local reflex arc. The economy of this system ensures that ‘survival’ mechanisms such as balance and sense of position in space are activated with great speed.
Human endogenous retrovirus K (HERV-K) env in neuronal extracellular vesicles: a new biomarker of motor neuron disease
Published in Amyotrophic Lateral Sclerosis and Frontotemporal Degeneration, 2022
Yuan Li, Yong Chen, Nan Zhang, Dongsheng Fan
Douville et al. reported that HERV-K transcripts were increased in patients with ALS, especially in the prefrontal lobe (15). Li et al. (16) suggested that the expression of HERV-K was increased in autopsy brain tissue of patients with ALS compared to healthy controls and patients with Alzheimer's disease (AD). And env was increased selectively in the cytoplasm of pyramidal cells and spinal anterior horn cells but not in glial cells, white matter, hippocampal neurons and posterior cord. Cells transfected with HERV-K or the env gene all resulted in atrophy and shortened processes, which were concentration-dependent. Transgenic mice expressing the full-length or TM of env exhibited atrophy of the motor cortex and decreased protrusions of pyramidal cells. Therefore, HERVs, especially HERV-K env, may be used as a marker for the diagnosis and monitoring of disease progression in MND. There is an urgent need for a noninvasive technique to detect the expression level of HERVs derived from the central nervous system.
Absent sural responses in tethered cord syndrome
Published in The Journal of Spinal Cord Medicine, 2021
Elia G. Malek, Johnny Salameh, Nour Estaitieh, Achraf Makki
Clinical and radiological evaluation remains the gold diagnostic standard in assessing TCS. Neurophysiologic testing including NCS, needle electromyography and evoked potentials (motor and somatosensory) may provide more insight into the extent of neuronal damage in addition to the diagnostic and prognostic value of the intra-operative motor evoked potential and somatosensory evoked potential monitoring during surgical detethering.8 Pre-operatively, NCS may show relatively (often asymmetric) abnormal responses in the motor components of peripheral nerves, prolongation in F-waves and H-reflex in the setting of intact sensory nerve responses. Needle electromyography may show evidence of denervation and reinnervation indicating a chronic neuronal injury. These findings suggest that the level of injury is localized to the anterior horn cells or cord roots.6
The CB2 cannabinoid receptor as a therapeutic target in the central nervous system
Published in Expert Opinion on Therapeutic Targets, 2021
David Cabañero, Elena Martín-García, Rafael Maldonado
Amyotrophic lateral sclerosis is a progressive neurodegenerative neuromuscular disease that primarily affects nerve cells and ends in the gradual loss of motor neurons that regulate voluntary muscle movement [114]. The progressive neuronal deterioration involves the spinal cord’s corticospinal tract, brainstem, and anterior horn cells. The neuronal loss characteristic of Amyotrophic lateral sclerosis seems associated with a mixture of several cytotoxic insults such as glutamate excitotoxicity and neuroinflammation in addition to protein aggregation or oxidative stress [115] and the possible pharmacological treatments should be directed to target these mechanisms. Riluzole is the only drug demonstrated to enhance Amyotrophic lateral sclerosis survival modestly, although no successful treatment is able to reverse the progression of the disease. Riluzole inhibits the kainate and NMDA receptors, stimulates glutamate uptake, prevents glutamate release from presynaptic terminals, potentiates GABAA receptors postsynaptically, and blocks TTX-sensitive sodium channels associated with damaged neurons [114]. Further studies are needed to develop novel therapeutic strategies based on increasing neuroprotection to counteract the neuroinflammation and excitotoxic events involved in Amyotrophic lateral sclerosis pathogenesis, and CB2r represents an excellent candidate target.