What is the possible diagnosis, testing, and treatment plan for a 26-year-old female patient (Pt) with persistent mouth pain and numbness on the left side of her mouth, especially when eating, drinking, and talking, after a normal dental examination?

Unilateral Mouth Pain with Numbness in a Young Female

This 26-year-old female most likely has post-traumatic trigeminal neuropathic pain or atypical odontalgia, and requires immediate neurologic evaluation with MRI imaging to rule out structural lesions, followed by initiation of neuropathic pain medications if imaging is negative. 1

Differential Diagnosis

The combination of unilateral continuous pain with numbness lasting 3 months after normal dental examination points strongly toward a neuropathic etiology rather than musculoskeletal or dental pathology. 1

Most Likely Diagnoses:

Post-traumatic trigeminal neuropathic pain/Atypical odontalgia is the primary consideration given:

• Continuous pain in the trigeminal distribution 1
• Associated numbness (altered sensation) on the left side 1
• Pain triggered by eating, drinking, and talking 1
• Normal dental examination excluding odontogenic causes 1
• Young female demographic (most common in women over age 30) 2

Temporomandibular disorder (TMD) remains possible but less likely because:

• TMD typically presents without numbness 1
• TMD is the most common non-dental facial pain (5-12% of population, peak age 20-40) 1
• However, the presence of numbness strongly suggests neuropathic rather than musculoskeletal pathology 1

Critical Red Flags to Exclude:

Malignancy must be ruled out urgently because:

• Cancer can present as progressive neuropathic pain 1
• Unilateral pain with numbness warrants imaging 3
• Any non-healing lesions, ulceration, or induration require immediate biopsy 3

Diagnostic Testing

Immediate Required Tests:

MRI of the brain and trigeminal nerve is mandatory to:

• Exclude structural lesions, tumors, or nerve compression 1
• Identify nerve injury or pathology 2
• Rule out malignancy presenting as neuropathic pain 1

Comprehensive cranial nerve examination must document:

• Specific areas of altered sensation (hypoesthesia, hyperesthesia, allodynia) 1
• Light touch sensitivity testing in all three trigeminal divisions 1
• Assessment for other neurologic deficits outside the trigeminal nerve 2

Qualitative sensory testing (QST) should be performed to:

• Quantify sensory abnormalities 1
• Differentiate peripheral versus central neuropathic mechanisms 4

Additional Diagnostic Considerations:

Detailed pain history focusing on:

• Any prior dental procedures (root canals, extractions, implants) that may have caused nerve injury 1
• History of inadequate analgesia during dental work (common in nerve injury cases) 1
• Trauma to the face or jaw 1
• Character of pain (burning, tingling, sharp versus aching) 1

Intraoral examination to:

• Confirm absence of mucosal lesions, ulceration, or masses 3
• Rule out oral candidiasis or other local pathology 5
• Assess for any visible abnormalities requiring biopsy 3

Treatment Plan

Initial Management:

Start gabapentin as first-line neuropathic pain medication because:

• Gabapentin is the recommended first-line agent for trigeminal neuropathic pain 6
• 50% of patients experience reduction in burning sensation 6
• Typical starting dose 300mg at bedtime, titrating up to 900-3600mg daily in divided doses 6

Alternative or adjunctive medications if gabapentin fails or is poorly tolerated:

• Amitriptyline (tricyclic antidepressant) has shown benefit in open-label studies 1
• Topical lidocaine for temporary relief 6
• Alpha lipoic acid combined with gabapentin for refractory cases 6

Multidisciplinary Approach:

Cognitive behavioral therapy (CBT) should be initiated early because:

• CBT is a primary intervention for chronic facial pain 1, 6
• Addresses psychological components that exacerbate symptoms 6
• Improves coping strategies and quality of life 1

Referral to pain specialist or neurologist if:

• Inadequate response after 4-6 weeks of initial treatment 6
• MRI reveals structural abnormalities requiring specialized management 2
• Pain becomes refractory to standard neuropathic medications 1

Important Caveats:

Avoid further dental procedures because:

• Up to one-third of chronic facial pain patients have undergone unnecessary irreversible dental procedures 2
• Additional dental work can worsen neuropathic pain 7
• Once dental pathology is excluded, further dental intervention is contraindicated 2, 7

Set realistic expectations as:

• Treatment failures are common in neuropathic facial pain 1, 6
• Less than 25% achieve complete pain relief once pain becomes chronic 2
• Early intervention improves outcomes and prevents psychiatric comorbidity 2

Monitor for psychiatric comorbidity because:

• Depression and anxiety commonly coexist with chronic facial pain 1, 8
• Unrelenting pain can alter personality and worsen quality of life 2, 8
• Comorbid psychiatric disorders negatively impact treatment outcomes 8