What are the possible etiologies and diagnoses for a patient experiencing tingling and swelling to one side of the face?

Unilateral Facial Tingling and Swelling: Terminology and Differential Diagnosis

Unilateral facial tingling and swelling does not have a single specific medical term, as these symptoms represent a constellation of findings that require systematic evaluation to identify the underlying etiology—the most critical distinction being whether this represents Bell's palsy (motor weakness), trigeminal neuropathy (sensory dysfunction), or a more serious condition requiring urgent imaging. 1

Key Clinical Distinctions

The combination of tingling (sensory symptoms) and swelling on one side of the face requires careful differentiation from several conditions:

Bell's Palsy (Motor Dysfunction)

• Bell's palsy causes unilateral facial muscle weakness or paralysis, NOT isolated sensory symptoms like tingling. 2, 3
• Onset occurs rapidly over less than 72 hours. 2
• Patients cannot close the eye, have drooping of the mouth corner, and loss of forehead wrinkles on the affected side. 2, 3
• If your patient describes tingling without motor weakness, this is NOT Bell's palsy. 1

Trigeminal Neuropathy (Sensory Dysfunction)

• Continuous numbness or tingling in the trigeminal distribution without paroxysmal pain attacks indicates trigeminal neuropathy, not neuralgia. 1
• This requires urgent MRI with contrast to evaluate for structural lesions, demyelination, or tumors. 1
• The presence of sensory deficits demands imaging to rule out secondary causes including multiple sclerosis, tumors, or inflammatory processes. 4, 5

Trigeminal Neuralgia (Pain Syndrome)

• Classical trigeminal neuralgia presents with sharp, shooting, electric shock-like pain lasting seconds to minutes with mandatory refractory periods—NOT continuous tingling or swelling. 4, 5
• Trigeminal neuralgia does not typically cause visible swelling or inflammation. 4
• If pain is continuous rather than paroxysmal, consider alternative diagnoses. 4, 5

Critical Red Flags Requiring Urgent Evaluation

Obtain MRI brain with contrast urgently if any of the following are present: 1

• Progressive or persistent symptoms beyond 2-4 months. 1
• Additional neurologic symptoms including dizziness, dysphagia, diplopia, or other cranial nerve involvement suggesting brainstem pathology. 2, 1
• Bilateral facial symptoms (rare in Bell's palsy and should prompt investigation for Lyme disease, sarcoidosis, or autoimmune conditions). 2, 1
• Sensory deficits in the trigeminal distribution. 4, 5
• Age over 50 with new facial symptoms (consider giant cell arteritis, particularly with jaw claudication, scalp tenderness, or visual symptoms). 1

Differential Diagnosis Algorithm

If Swelling WITH Motor Weakness:

1. Bell's palsy - Most common cause of acute unilateral facial paralysis (70% of facial nerve palsies). 2, 3

   • Rapid onset over less than 72 hours. 2
   • Inability to close eye, forehead involvement, mouth drooping. 2, 3
   • Treat with oral steroids within 72 hours for patients 16 years and older. 2
   • Implement eye protection for impaired eye closure. 2

2. Stroke - Must be excluded urgently. 2

   • Look for forehead sparing (central facial palsy spares forehead, peripheral does not). 2
   • Associated symptoms: sudden confusion, trouble speaking, vision changes, trouble walking, severe headache. 2
   • Use Cincinnati Prehospital Stroke Scale: facial droop, arm drift, abnormal speech. 2

If Tingling WITH Autonomic Features (Tearing, Red Eye, Nasal Congestion):

• Trigeminal autonomic cephalgias (SUNCT/SUNA) - Up to 200 attacks daily with no refractory period. 4
• Prominent autonomic symptoms including tearing, conjunctival injection, rhinorrhea, facial redness. 4
• Attacks last seconds to several minutes. 4

If Tingling WITHOUT Motor Weakness or Pain:

• Trigeminal neuropathy - Requires MRI brain with contrast to evaluate for: 1
  • Demyelinating lesions (multiple sclerosis). 4
  • Tumors compressing the trigeminal nerve. 4, 1
  • Vascular compression or inflammatory processes. 1

Other Important Etiologies to Consider

Post-infectious causes: 4

• Post-herpetic neuralgia following herpes zoster (continuous burning pain at site of previous rash with allodynia). 4
• History of vesicular rash in trigeminal distribution. 4

Trauma-related: 4

• Post-traumatic trigeminal neuropathic pain developing within 3-6 months of dental procedure or facial trauma. 4
• Continuous burning or tingling quality. 4

Systemic conditions: 2

• Lyme disease (check serology only in endemic areas with appropriate exposure history). 2, 1
• Sarcoidosis. 2
• Diabetes mellitus (increases risk of Bell's palsy). 2, 3

Diagnostic Workup

Do NOT routinely obtain: 2

• Laboratory testing in new-onset Bell's palsy (unless specific risk factors present). 2
• Diagnostic imaging for straightforward Bell's palsy presenting within 72 hours. 2

DO obtain urgently: 1

• MRI brain with contrast for any sensory symptoms without clear motor weakness. 1
• High-resolution temporal bone CT is complementary but should not replace MRI. 1
• ESR and CRP if giant cell arteritis suspected (age >50, temporal headache, jaw claudication). 1

Common Pitfalls to Avoid

• Do not assume Bell's palsy if the patient describes tingling without motor weakness—this suggests trigeminal neuropathy requiring imaging. 1
• Do not miss stroke—central facial palsy spares the forehead, while Bell's palsy involves the entire side of the face including forehead. 2
• Do not delay imaging if symptoms are bilateral—this is rare in Bell's palsy and suggests systemic disease. 2, 1
• Do not confuse trigeminal neuralgia with trigeminal neuropathy—neuralgia is paroxysmal pain with refractory periods, while neuropathy is continuous sensory dysfunction. 4, 1, 5