What is the recommended treatment for a patient with a hypoglossal nerve injury?

Management of Hypoglossal Nerve Injury

The primary treatment for hypoglossal nerve injury is supportive care with speech therapy and dietary modifications to prevent aspiration, as most patients (69%) recover completely within 6 months without specific intervention. 1

Initial Diagnostic Approach

Comprehensive imaging is essential to identify the underlying cause, as tumors are the most common etiology of hypoglossal nerve palsy. 2

Recommended Imaging Protocol

• MRI with contrast of the orbits, face, and neck is the primary imaging modality to evaluate the entire course of the hypoglossal nerve from brainstem through the hypoglossal canal to the suprahyoid neck 2
• Pre- and post-contrast imaging provides optimal identification and characterization of lesions causing nerve compression or injury 2
• Thin-cut heavily T2-weighted contrast-enhanced modified balanced SSFP sequences and contrast-enhanced MRA focused on the posterior skull base provide detailed visualization with 90-100% visibility of CN XII 2
• MRI demonstrates superior sensitivity (100%) for detecting pathology compared to CT, though with lower specificity (59%) 2
• CT provides complementary information about bony structures of the hypoglossal canal when needed 2

Clinical Assessment

Key Physical Examination Findings

• Tongue deviation toward the side of the lesion upon protrusion is the primary clinical sign of lower motor neuron hypoglossal nerve injury 3
• Unilateral tongue wasting or fatty infiltration indicates chronic denervation 3
• Dysarthria with difficulty articulating lingual consonants reflects impaired tongue motor function 3, 4

Distinguish Lower vs Upper Motor Neuron Lesions

• Lower motor neuron lesions cause tongue deviation toward the lesion side with visible atrophy and fasciculations 3
• Upper motor neuron lesions cause deviation away from the lesion side without atrophy or fasciculations 3
• Assess for involvement of other cranial nerves (CN IX, X, XI) which may indicate jugular foramen or brainstem pathology 3

Treatment Strategy

Supportive Management (Primary Approach)

• Speech therapy is the cornerstone of supportive treatment to improve articulation and swallowing function 1
• Dietary modifications are essential to prevent aspiration in patients with dysphagia 1
• No proven effective medical or surgical treatment exists for hypoglossal nerve injury itself 1

Prognosis and Recovery

• 69% of patients recover completely within the first 6 months following injury 1
• Recovery is generally favorable with supportive care alone 1
• Earlier initiation of speech therapy and dietary modifications may improve outcomes 5

Etiology-Specific Considerations

Iatrogenic Injury (Intubation-Related)

• Hypoglossal nerve palsy can result from compression between the endotracheal tube and hyoid bone during prolonged intubation 5, 1
• Stretch injury during difficult airway instrumentation is another mechanism 5, 6
• Risk factors include prolonged intubation, difficult airway requiring multiple attempts, and tongue swelling from large fluid shifts 5

Neoplastic Causes

• Tumors are the most common cause of hypoglossal nerve palsy involving the intracranial, skull base, and cervical segments 3
• Treatment directed at the underlying tumor (surgical resection, radiation) is required when identified 2

Other Etiologies

• Brainstem infarction, demyelinating disease, vascular lesions, infectious processes, and surgical dissection are additional causes requiring specific treatment 4, 5

Common Pitfalls to Avoid

• Do not confuse tongue deviation with facial asymmetry from facial nerve palsy, which affects facial muscles but not tongue protrusion 3
• Recognize that the extracranial segment of the hypoglossal nerve in the suprahyoid neck is difficult to visualize directly and must be inferred from anatomical knowledge 2
• Be aware of rare anatomical variants where the hypoglossal nerve courses superficial to the internal jugular vein, increasing surgical injury risk 7