LAUSR

Hypoxic jaw clenching due to cerebrocortical oxygen deprivation has been described following polytrauma, overdose and seizures. Senthilkumaran et al. surmise that extreme oxygen and glucose deprivation cause a neurotransmitter and free radical surge, and disturbance in neuronal transmission. This leads to a global increase in resting muscle tension, particularly pronounced in the masseter muscle. Hypertonus eventually subsides due to brainstem hypoxia, possibly explaining why the trismus abated. Notably, this is resistant to suxamethonium. Whether this is related to ‘instantaneous rigor mortis’, also known as ‘cadaveric spasm’, is uncertain. This rare occurrence, characterised by sudden-onset rigor, leads to bodies being found in unusual positions for example standing. Extreme depletion of ATP stores in muscle cells renders them unable to relax. It typically only affects a group of muscles such as the hands rather than the whole body.