Anatomical Basis of Hypoglossal Nerve Palsy

The hypoglossal nerve (CN XII) is a crucial motor nerve responsible for the movements of the tongue. Any impairment in this nerve can lead to hypoglossal nerve palsy, causing difficulties in speech, swallowing, and tongue movement.

Etiology and Pathogenesis

Causes of Hypoglossal Nerve Palsy

• Trauma: Surgical procedures, head and neck injuries.
• Neoplastic: Tumors compressing the hypoglossal nerve.
• Neurological: Stroke, multiple sclerosis, or Guillain-Barré syndrome.
• Idiopathic: Unknown causes, sometimes linked to viral infections.

Pathogenesis

The hypoglossal nerve originates from the hypoglossal nucleus in the medulla oblongata and exits the skull through the hypoglossal canal. Damage to this nerve disrupts motor function, leading to unilateral or bilateral tongue weakness. Chronic conditions may result in muscle atrophy.

Clinical Manifestations

• Unilateral or bilateral tongue deviation.
• Dysarthria (difficulty in speech).
• Dysphagia (difficulty swallowing).
• Atrophy of tongue muscles.

Diagnosis and Management

Diagnostic Approaches

• Imaging: MRI/CT scan to identify structural abnormalities.
• Electromyography (EMG): To assess nerve conduction and muscle function.
• Blood tests: To check for infectious or autoimmune causes.

Treatment Options

• Addressing underlying cause: Treating infections, tumors, or vascular issues.
• Physical therapy: Speech and swallowing rehabilitation.
• Surgical intervention: In cases of compressive lesions.