A. Deviation of tongue.
B. Muscular twitching.
C. Hemiatrophy of tongue.
D. None of the above.
Ans;C. Hemiatrophy of tongue
The nerve represented by a yellow color in the picture above represents the Hypoglossal nerve.
Hypoglossal nerve palsy: Hypoglossal nerve (cranial nerve XII) palsy is uncommon. Damage to this nerve produces characteristic clinical manifestations, of which uni- lateral atrophy of the tongue musculature is the most important.
- Unilateral palsy results in mild deviation of tongue towards the paretic side when it is protruded.
- Bilateral supranuclear palsy produces severe dysarthria and dysphagia.
- Nuclear lesions of hypoglossal nerve results in bilateral flaccid paralysis of the tongue with atrophy and fasciculations. Speech and swallowing are impaired.
- Supra nuclear palsy of hypoglossal nerve does not result in atrophy, but intranuclear lesions can lead to hemiatrophy of tongue on the affected side. Deviation of tongue to the affected side, muscular twitching are seen in both types.
- The action of the hypoglossal nerve is entirely motor.
- The balanced action of both genioglossus muscles is necessary to protrude the tongue in the midline.
- Disorders affecting the function of the hypoglossal nerve lead to imbalanced action of the genioglossus muscles, causing tongue deviation toward the weak side.
- Supranuclear disease affecting the nerve results in paralysis of the tongue contralateral to the side of the lesion. Deviation of the tongue will occur away from the side of the lesion. Fasciculation and atrophy of the tongue are absent.
- When disease affects the hypoglossal nerve at the nuclear or infranuclear level, the clinical signs and symptoms are ipsilateral. There is dcviation of the tongue toward the side of the lesion, with associated atrophy of the intrinsic and extrinsic tongue musculature and fasciculation of the tongue. This constellation may lead to dysarthric speech.