What is the workup and management for a patient with left lateral tongue deviation?

Workup and Management of Left Lateral Tongue Deviation

Left lateral tongue deviation requires urgent neuroimaging to localize the lesion, as it most commonly indicates a contralateral (right-sided) pontine or supratentorial stroke affecting corticohypoglossal fibers before their decussation, though ipsilateral lower motor neuron lesions remain in the differential. 1, 2

Initial Diagnostic Workup

Immediate Clinical Assessment

• Determine if deviation is toward or away from limb weakness - tongue deviation to the same side as hemiparesis indicates an upper motor neuron (supranuclear) lesion contralateral to the deviation 3
• Quantify the deviation angle - angles >3.2° predict stroke risk with 96% discrimination (AUC = 0.96), while normal subjects typically show <1.4° ± 0.8° of deviation 4
• Assess for associated cranial nerve findings - supranuclear tongue palsy is universally associated with ipsilateral facial weakness (supranuclear 7th nerve palsy) 3
• Evaluate for dysarthria and dysphagia - present in 90% and 43% of patients with supranuclear tongue deviation respectively, indicating larger non-lacunar infarcts 3
• Check for fasciculations and atrophy - their absence supports upper motor neuron pathology rather than hypoglossal nucleus or nerve lesions 2

Neuroimaging Protocol

• Obtain MRI brain with diffusion-weighted imaging immediately - this localizes pontine infarctions affecting corticohypoglossal fibers in the ventromedial pons or larger cortical/subcortical lesions 1, 2
• Focus on the left paramedian pontine region - contralateral (right-sided) tongue deviation with right hemiparesis indicates left pontine involvement of corticohypoglossal and corticospinal tracts before decussation 2
• Evaluate for cortical or large subcortical infarctions - tongue deviation occurs in 55% of cortical and 45% of large subcortical infarcts, indicating non-lacunar stroke subtype 3

Differential Diagnosis Considerations

• Acute motor axonal neuropathy (AMAN) - if tongue deviation is ipsilateral to limb weakness with tongue swelling, obtain nerve conduction studies showing motor axonal neuropathy with sensory sparing, CSF for albuminocytologic dissociation, and anti-GD1b IgG antibody testing 5
• Functional movement disorder - assess for inconsistent movements varying with attention or distraction, excessive effort, sudden onset following stressor, and symptom variability during spontaneous conversation 6
• Progressive bulbar palsy in ALS - if subacute onset with fasciculations, obtain videofluoroscopy to detect early dysphagia signs, though sensory symptoms would be atypical 7, 8

Management Based on Etiology

Acute Ischemic Stroke (Most Common)

• Initiate acute stroke protocol - if within therapeutic window, consider thrombolysis or thrombectomy per institutional stroke protocols 3
• Address dysphagia immediately - 43% of patients with tongue deviation have dysphagia; obtain videofluoroscopy or FEES to assess aspiration risk 7, 3
• Implement compensatory swallowing strategies - chin-tuck posture protects the airway during swallowing; modify texture of solids and liquids based on instrumental swallowing study results 7
• Provide speech therapy with motor retraining - for dysarthria present in 90% of cases with tongue deviation 6, 3

Functional Movement Disorder

• Make a positive diagnosis based on internal inconsistency - demonstrate to the patient that symptoms resolve during spontaneous conversation or when attention is diverted 6, 9
• Implement intensive speech and language therapy - multiple sessions per week with motor retraining, attention redirection, and natural reflexive behaviors 6
• Address psychiatric comorbidities concurrently - treat depression with SSRIs or low-dose amitriptyline, as mental health disorders prevent maintenance of treatment gains 9
• Avoid dismissing as "psychogenic" - these are genuine neurological conditions requiring active treatment, not exclusion diagnoses 6

Acute Motor Axonal Neuropathy

• Administer intravenous immunoglobulin - standard treatment for AMAN with slow but expected improvement 5
• Monitor respiratory function - progression to tetraparesis may occur within days requiring ventilatory support 5

Critical Pitfalls to Avoid

• Do not assume bilateral symmetrical supranuclear innervation - 29% of acute stroke patients demonstrate tongue deviation, indicating asymmetrical supranuclear control of the hypoglossal nucleus in many individuals 3
• Do not overlook dysphagia screening - the association between tongue deviation and dysphagia in large infarcts has direct clinical utility for aspiration prevention 3
• Do not delay neuroimaging in young patients or those without vascular risk factors - atypical presentations require urgent imaging to exclude structural lesions 7
• Do not focus exclusively on tongue symptoms while ignoring depression or anxiety - this leads to treatment failure and relapse in functional disorders 9
• Do not assume sensory symptoms exclude ALS - electromyography can detect sensory nerve conduction abnormalities in ALS patients with prominent sensory symptoms 8