Neuroscience · Year 2 · from Neuroscience
Case 3: Trigeminal Neuralgia
Patient Presentation
Demographics: 62-year-old male
Chief Complaint: Severe shooting facial pain for 2 months
History of Present Illness: The patient describes 2 months of recurrent, excruciating pain on the right side of his face. The pain is "like electric shocks" or "lightning bolts," occurring in the right cheek and jaw. Each episode lasts only a few seconds but is so severe he stops whatever he is doing. The pain is triggered by chewing, brushing his teeth, shaving, or even a light breeze on his face. He has had up to 20-30 episodes per day. He has lost 8 pounds because eating triggers the pain. Between attacks, he has no pain. The pain has never occurred on the left side or awakened him from sleep.
Physical Examination:
- Vital signs: BP 148/86, HR 72, T 36.9C
- General: Appears apprehensive; has not shaved right side of face; protective of right cheek
- Neurological:
- Mental status: Normal
- Cranial nerves:
- Light touch to right V2 and V3 distributions triggers severe lancinating pain lasting 2-3 seconds (patient withdraws and grimaces)
- Between triggers, sensation to light touch, pinprick, and temperature is NORMAL in all trigeminal divisions
- Corneal reflex intact bilaterally
- Motor function of V3 (masseter, temporalis) intact
- All other cranial nerves normal
- Motor/Sensory/Reflexes: Normal throughout
Workup:
- MRI brain with thin cuts through posterior fossa: No mass lesion; tortuous loop of right superior cerebellar artery in close contact with the right trigeminal nerve root entry zone, consistent with neurovascular compression
- No laboratory abnormalities: TSH, basic metabolic panel, CBC normal
Diagnosis: Classical trigeminal neuralgia (tic douloureux) with neurovascular compression
Treatment:
- Carbamazepine 100 mg twice daily, titrated to 200 mg three times daily
- Baseline CBC and hepatic function panel (monitor for carbamazepine toxicity)
- HLA-B*15:02 testing (patient of Asian descent - risk of severe cutaneous reactions)
Clinical Course: Pain frequency decreased by 80% within 2 weeks of reaching therapeutic carbamazepine dose. At 3-month follow-up, he was experiencing only 1-2 mild attacks per day. He discussed surgical options (microvascular decompression) if medication becomes ineffective or intolerable but elected to continue medical management for now.
Clinical Pearl: Trigeminal neuralgia is characterized by severe, brief, shock-like pain in the distribution of one or more trigeminal divisions, triggered by innocuous stimuli. V2 and V3 are most commonly affected. Between attacks, the neurological examination is normal - any sensory deficit should raise concern for a structural lesion or secondary cause. Most cases are caused by vascular compression of the trigeminal root entry zone. Carbamazepine is first-line treatment; microvascular decompression surgery is highly effective for refractory cases.
Clinical Image
Image Description: Clinical photograph or illustration demonstrating characteristic features of lower motor neuron facial nerve palsy (Bell's palsy), including inability to close the eye, flattening of the forehead (distinguishing from UMN lesions), and drooping of the corner of the mouth. The entire hemiface is affected because all facial nerve motor fibers pass through the same peripheral pathway.
Attribution: Image from Radiopaedia (https://radiopaedia.org/), Creative Commons Attribution-NonCommercial-ShareAlike 3.0 license.