Unilateral Facial Numbness and Tingling Without Rash or Pain

Diagnostic Approach

The American College of Radiology recommends MRI of the brain with contrast as the essential first-line imaging study to evaluate the trigeminal nerve pathway from brainstem to peripheral branches 1
MRI provides superior soft tissue resolution to identify demyelinating lesions, tumors, vascular compression, and inflammatory processes 1
High-resolution temporal bone CT is complementary to MRI when evaluating osseous integrity and bony canal involvement, but should not replace MRI as the initial study 1

Progressive or persistent symptoms beyond 2-4 months warrant imaging even if initially thought to be Bell's palsy 1
Additional neurologic symptoms, including dizziness, dysphagia, diplopia, or other cranial nerve involvement, suggest brainstem pathology rather than isolated peripheral nerve disease 2, 3
Bilateral facial symptoms are rare in Bell's palsy and should prompt investigation for systemic causes, including Lyme disease, sarcoidosis, or autoimmune conditions 3
Age over 50 with new facial symptoms requires consideration of giant cell arteritis, particularly if accompanied by jaw claudication, scalp tenderness, or visual symptoms 4, 5

Classical trigeminal neuralgia presents with paroxysmal attacks lasting seconds to minutes with mandatory refractory periods—not continuous numbness or tingling 4, 6
Trigeminal neuralgia causes sharp, shooting, electric shock-like pain triggered by light touch, not sensory loss 4, 6
The presence of continuous numbness without paroxysmal pain attacks indicates trigeminal neuropathy, not neuralgia 6
Bell's palsy causes motor weakness or paralysis of facial muscles, not isolated sensory symptoms 2, 3

Obtain MRI brain with contrast urgently to evaluate for structural lesions, demyelination, or vascular pathology 1
Perform comprehensive neurologic examination documenting all cranial nerve function, not just facial sensation 2, 3
ESR and CRP should be checked if giant cell arteritis is suspected (age >50, temporal headache, jaw claudication) 4, 5
Lyme serology should only be checked in endemic areas with appropriate exposure history 2