Can the tongue exhibit neurological symptoms?

Can the Tongue Exhibit Neurological Symptoms?

Yes, the tongue can exhibit multiple neurological symptoms, most commonly manifesting as weakness, paralysis with deviation to the affected side, involuntary movements (dystonia), impaired bolus transport, and reduced tongue driving forces during swallowing.

Primary Neurological Manifestations

Hypoglossal Nerve (CN XII) Palsy

• Tongue weakness and paralysis occur when the hypoglossal nerve is damaged, causing the tongue to deviate toward the affected side on protrusion, accompanied by dysarthria 1
• Atrophy and fatty infiltration of tongue muscles develop over time and can be visualized on imaging studies 1
• Lesions affecting CN XII include posterior fossa infarctions, meningiomas, schwannomas, paragangliomas, carcinomas, metastases, subarachnoid hemorrhage, Chiari malformations, basilar invagination, and fractures 1

Motor Dysfunction in Neurodegenerative Disease

• In ALS patients, impaired tongue movement manifests as reduced tongue driving forces and decreased bolus transport from the oral cavity to the pharynx, even in patients without bulbar symptoms 1
• Tongue base retraction becomes impaired specifically when bulbar symptoms are present in ALS, while lingual elevation and tongue movement to palatal seal are typically preserved early in disease 1
• Bolus holding in the oral cavity and oral residue are affected regardless of whether bulbar symptoms are clinically apparent 1
• Videofluoromanometric studies demonstrate that decreased swallowing pressure first appears in the oropharynx, with low tongue driving forces being a cardinal finding 1

Movement Disorders

• Severe tongue protrusion dystonia can occur intermittently or be sustained, causing speech, swallowing, and breathing difficulties severe enough to be life-threatening 2
• This dystonic syndrome is associated with neuroacanthocytosis, pantothenate kinase-associated neurodegeneration, Lesch-Nyhan syndrome, and postanoxic and tardive dystonia 2
• The pathophysiology remains incompletely understood, but treatment may include botulinum toxin injections into the genioglossus muscle or bilateral deep brain pallidal stimulation 2

Sensory Neurological Symptoms

Burning Mouth Syndrome (Primary BMS)

• Primary BMS represents a neuropathic pain condition affecting the tongue tip and anterior two-thirds most commonly, presenting as continuous burning, stinging, or itchy sensations with normal-appearing oral mucosa 3, 4
• This condition predominantly affects peri- and post-menopausal women and requires neuropathic pain management rather than local treatments 3
• Management includes cognitive behavioral therapy, gabapentin, alpha-lipoic acid, and topical clonazepam or diazepam 3, 4

Post-Traumatic and Post-Infectious Neuropathy

• Post-traumatic trigeminal neuropathic pain can develop within 3-6 months following dental procedures or facial trauma, presenting as continuous burning or tingling 3
• Post-herpetic neuralgia following herpes zoster causes continuous burning, tingling, or itchy sensations at the site of previous infection 3

Clinical Pitfalls and Diagnostic Considerations

Avoid Premature Psychogenic Attribution

• Tongue pain without visible lesions should not be dismissed as psychogenic without thorough evaluation, including laboratory workup for nutritional deficiencies, diabetes, thyroid dysfunction, and medication review 3, 4
• Essential blood tests include CBC with differential, iron studies, vitamin B12, fasting glucose and HbA1c, vitamin D 25(OH), and thyroid function tests 3

Distinguish from Malignancy

• Unilateral pain, ulceration, induration, or non-healing lesions mandate biopsy to rule out malignancy, particularly in patients with tobacco use, alcohol consumption, or HPV infection 4
• Tongue biopsy is necessary when suspicious lesions are present or when unilateral symptoms suggest structural pathology rather than functional neuropathy 3, 4

Imaging Approach for Neurological Causes

• MRI is the preferred modality for evaluating the entire course of the hypoglossal nerve from the brain stem medulla through the cisternal segment to the high carotid space 1
• CT provides complementary information on bony structures and foramina integrity 1
• Evaluation should cover the nucleus in the brain stem, cisternal segment, and high carotid space to identify infarctions, tumors, or structural lesions 1