CN XII Lesion

A CN XII lesion affects the hypoglossal nerve, which controls the muscles of the tongue. This nerve is part of the nervous system and is essential for movements involved in speech, swallowing, and chewing. When this nerve is damaged, it can cause weakness or paralysis of the tongue on one side. This leads to difficulties with clear speech and swallowing, which can impact nutrition and communication. The tongue may also deviate toward the side of the lesion when protruded, which is a key sign of this condition.

CN XII lesion refers to damage of the hypoglossal nerve, a cranial nerve responsible for motor innervation of the intrinsic and extrinsic muscles of the tongue. The lesion can be caused by trauma, tumors, stroke, or infections affecting the nerve along its course from the brainstem to the tongue. Clinically, it presents with ipsilateral tongue weakness, atrophy, and fasciculations. The tongue deviates toward the side of the lesion upon protrusion due to unopposed action of the contralateral genioglossus muscle. This lesion is significant because it impairs speech articulation and swallowing, increasing the risk of aspiration. Diagnosis requires careful neurological examination and imaging to identify the underlying cause.