Complications of Hypoglossal Neuropraxia
Beyond the primary manifestations of tongue deviation and dysarthria, hypoglossal neuropraxia causes dysphagia as a significant additional complication, and in rare bilateral cases can lead to severe airway compromise and nutritional difficulties. 1, 2
Primary Complications
Swallowing Dysfunction (Dysphagia)
- Dysphagia occurs alongside dysarthria and tongue deviation as a core complication of hypoglossal nerve injury, resulting from impaired tongue motor control necessary for the oral phase of swallowing 1, 2
- This swallowing difficulty can lead to aspiration risk and nutritional compromise, particularly in bilateral cases 2
Speech Impairment (Dysarthria)
- Dysarthria with specific difficulty articulating lingual consonants is a hallmark complication, reflecting the tongue's critical role in speech production 3, 4
- The severity correlates with whether the lesion is unilateral or bilateral 2
Tongue Muscle Changes
- Chronic denervation leads to unilateral tongue wasting or fatty infiltration, visible as decreased bulk on the affected side 4, 5
- Fasciculations may be present in lower motor neuron lesions, distinguishing them from upper motor neuron pathology 4
Bilateral Hypoglossal Neuropraxia - Critical Complications
Severe Functional Impairment
- Bilateral involvement causes complete tongue immobility, which is far more debilitating than unilateral palsy 2
- This results in profound dysphagia requiring potential nutritional support and aspiration precautions 2
Airway Considerations
- While not explicitly causing airway obstruction in most cases, bilateral tongue immobility can compromise airway protection mechanisms 2
Associated Cranial Nerve Involvement
Multiple Nerve Palsies
- Lesions at the jugular foramen or brainstem may simultaneously affect cranial nerves IX, X, XI, and XII, creating complex clinical pictures with combined swallowing, voice, and tongue dysfunction 4
- Nuclear brainstem lesions typically present with additional brainstem signs beyond isolated hypoglossal dysfunction 4
Recovery Timeline and Prognosis
Expected Recovery Course
- 50% of patients with post-procedural hypoglossal neuropraxia recover within 2 months 1
- 80% achieve complete resolution within 4 months 1
- Complete recovery is possible even in bilateral cases, though it may take up to 4 months 2
Monitoring for Serious Etiologies
- The diagnosis is frequently missed initially due to delayed symptomatic onset, and requires neurology and otolaryngology evaluation to exclude serious underlying causes such as tumors, vascular lesions, or brainstem pathology 1
- MRI with contrast is the primary imaging modality to evaluate the entire course of the hypoglossal nerve and identify compressive or infiltrative lesions 5
Common Clinical Pitfalls
Diagnostic Confusion
- Do not confuse tongue deviation with facial asymmetry from facial nerve (CN VII) palsy, which affects facial muscles but not tongue protrusion 4, 5
- Recognize that symptoms may have delayed onset after the inciting event, particularly in post-anesthesia cases 1
Missed Bilateral Cases
- Bilateral hypoglossal palsy is extremely rare and can be overlooked if tongue protrusion is not specifically tested, as the tongue may remain midline but immobile 2