Case Presentation: The patient is a 69 year old female with a past medical history of trigeminal neuralgia and hypertension who presented with complaints of 5 days of tremors, dizziness and right-sided facial pain. She was recently diagnosed with trigeminal neuralgia and was placed on a regimen of carbamazepine and gabapentin. Shortly after starting these medications the patient started to experience additional neurological symptoms along with her pain including dizziness, diplopia, and resting tremors of bilateral hands which prompted her to come to the hospital. On exam there were no focal neurological deficits noted. It was decided to decrease the carbamazepine and increase the gabapentin dosing. Subsequently, the dizziness, diplopia and resting tremors had dissipated; however, her pain severely exacerbated as a result. Despite given a myriad of therapy to diminish her pain, it remained uncontrolled.
Discussion: Carbamazepine is an anti-seizure medication used in the treatment of seizures and neuropathic pain. It acts by inhibiting cellular voltage gated sodium channels prompting the cell’s inactive phase, leading to decreased frequency and inhibition of the action potentials that contribute to pain. Carbamazepine may require increased dosages to alleviate a patient’s symptoms.Trigeminal neuralgia is a rare clinical diagnosis of severe sharp, stabbing pain in the distribution of the fifth cranial (trigeminal) nerve. Patients have described this pain as an electric shock-like sensation, lasting from seconds to hours. Carbamazepine is currently considered the first line medication for treatment of trigeminal neuralgia. Unfortunately, many patients are unable to tolerate this medication due to its severe adverse effects, most commonly dizziness. While tremors are a well known withdrawal symptom from sudden discontinuation of the medication, there is limited data identifying tremors as an adverse reaction. In our patient, the tremors were severe and debilitating. With a decreased dose of carbamazepine, the tremors began to resolve. While the presenting symptoms improved, the patient experienced a severe trigeminal neuralgia pain exacerbation. Multiple abortive and adjunctive therapies were utilized to decrease the patient’s pain including baclofen, gabapentin, topical lidocaine gel and phenytoin with no improvement of her pain. With the severity of this patient’s pain, attempts were made to reincorporate higher doses of carbamazepine closer to the patient’s home dose, however the tremors recurred.After several days of improving tremors with worsening trigeminal neuralgia pain, it was decided to transfer this patient to a neurosurgical service for gamma knife radiosurgery. About one month after surgery, the patient reports complete resolution of her pain. She remains on a lower and more manageable dose of carbamazepine with gabapentin and has no further reports of tremors. While this case presents one adverse effect of carbamazepine use, it remains the most commonly used medication in the treatment of trigeminal neuralgia. Due the uncommon nature of this disease, research towards novel treatment and methods of diagnosis continue to be investigated.
Conclusions: Carbamazepine is currently used as a mainstay therapy for trigeminal neuralgia. By sharing this case we aim to bring light to a rare adverse effect of high doses of carbamazepine, which can help hospitalists with their differential diagnosis of neurological symptoms.