Which symptom is common to both myasthenic and cholinergic crises?

Dysphagia, which refers to difficulty swallowing, is a common symptom observed in both myasthenic and cholinergic crises. In a myasthenic crisis, the underlying issue is the autoimmune attack on the neuromuscular junction, leading to muscle weakness that can affect muscles responsible for swallowing. In a cholinergic crisis, typically caused by an excess of acetylcholine due to anticholinesterase medication or other factors, muscle weakness can also manifest, impacting the coordination of the muscles involved in swallowing.

The presence of dysphagia in both conditions highlights the overlapping neuromuscular impairment associated with their pathophysiology. In myasthenic crises, the weakness is primarily caused by the insufficient stimulation of the muscles, while in cholinergic crises, excessive stimulation can disrupt normal swallowing function as well.

Other symptoms listed, such as severe headache, hypertension, and nausea, do not typically represent both conditions. Severe headache is more associated with different neurological issues, hypertension is not a significant feature in either crisis, and while nausea may occur due to various factors, it is less specifically tied to the core mechanisms of these crises compared to dysphagia.