Background: The reticulospinal tract (RST) is essential for balance, posture, and strength, all functions which falter with age. We hypothesized that age-related strength reductions might relate to differential changes in corticospinal and reticulospinal connectivity.Methods: We divided 83 participants (age 20–84) into age groups <50 (n = 29) and ≥50 (n = 54) years; five of which had probable sarcopenia. Transcranial Magnetic Stimulation (TMS) was applied to the left cortex, inducing motor evoked potentials (MEPs) in the biceps muscles bilaterally. Contralateral (right, cMEPs) and ipsilateral (left, iMEPs) MEPs are carried by mainly corticospinal and reticulospinal pathways respectively; the iMEP/cMEP amplitude ratio (ICAR) therefore measured the relative importance of the two descending tracts. Grip strength was measured with a dynamometer and normalized for age and sex.Results: We found valid iMEPs in 74 individuals (n = 44 aged ≥50, n = 29 < 50). Younger adults had a significant negative correlation between normalized grip strength and ICAR (r = −0.37, p = 0.045); surprisingly, in older adults, the correlation was also significant, but positive (r = 0.43, p = 0.0037).Discussion: Older individuals who maintain or strengthen their RST are stronger than their peers. We speculate that reduced RST connectivity could predict those at risk of age-related muscle weakness; interventions that reinforce the RST could be a candidate for treatment or prevention of sarcopenia.
The serotonin syndrome is a life-threatening adverse drug reaction resulting from excess serotonergic agonism due to interactions between multiple drugs, poisoning, or less commonly due to therapeutic action of a single drug. The central triad of features in serotonin syndrome are altered mental state, autonomic hyperactivity, and neuromuscular abnormalities in the context of a patient with new/altered serotonergic therapy, although not all these features are consistently present in all patients. The severity of serotonin syndrome can be assessed clinically based on the number and severity of features. Severe serotonin syndrome warrants more careful management on a high-dependency unit. In case of temperature exceeding 38.5°C, urgent cooling measures and sedation should be employed, progressing to rapid sequence intubation and paralysis if cooling measures are ineffective.
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