Shivering with yawning
Shivering with yawning can represent physiologic myoclonus in otherwise healthy people and usually does not require treatment. [1,2] A cause for concern increases when the episodes are persistent or severe or are accompanied by neurological impairment or other concerning symptoms. [1]
Likely benign mechanism
Physiologic myoclonus includes sudden, brief involuntary twitching or jerking that occurs in otherwise healthy people. [1] Hypnic and startle-like physiologic jerks can resemble a startle reaction. [1,2] Myoclonic jerks can also be triggered by attempts to make a conscious movement. [1]
When concern is warranted
Pathologic myoclonus is more likely when symptoms are persistent and severe and limit the ability to eat, talk, or walk. [1] Episodes that include other neurological symptoms such as altered awareness or loss of consciousness increase concern for an underlying disorder. [3] New myoclonus that is associated with a medication change, systemic illness, or metabolic disturbance increases concern for secondary causes. [3]
Initiation of evaluation
Evaluation is recommended when myoclonus is not clearly physiologic or when red-flag features are present. [1,3] Initial evaluation typically includes a neurological examination and characterization of triggers and distribution of the jerks. [3] Laboratory testing for electrolytes, glucose, renal function, hepatic function, and basic thyroid studies is recommended in many patients with myoclonus unless the presentation is clearly physiologic with no concerning history. [3]
Common pitfalls to avoid
Interpreting brief, stimulus-associated shivering as evidence of a progressive neurological disease without other abnormalities increases the risk of unnecessary alarm. [1,3] Assuming all involuntary movements are benign increases the risk of missing pathologic myoclonus that is persistent or function-limiting. [1]
Targets for clinical reassurance
Reassurance is most appropriate when the jerks are brief, infrequent, stimulus-linked (such as yawning), and not associated with functional limitation or other neurological symptoms. [1,2] When physiologic myoclonus is suspected, management typically consists of explanation and reassurance. [3]
Escalation criteria
Urgent evaluation is recommended when episodes are accompanied by loss of consciousness, impaired awareness, or other significant neurological deficits. [1,3] Non-urgent but prompt medical evaluation is recommended when jerks become persistent, worsen in severity, or begin to interfere with eating, talking, or walking. [1]