Backgrounds and aims: Trigeminal neuralgia is one of the most disabling facial pain syndromes, with a significant impact on patients' quality of life. Pharmacotherapy is the first choice for treatment but cases of drug resistance or adverse effects often require new strategies. In recent years a new therapeutic strategy consisting of botulinum toxin has emerged, with promising results.
Methods: 70-year-old patient, allergic to all NSAIDs with epidermoid cancer of the oropharynx in 2015 treated with chemotherapy and radical radiotherapy. Recurrence intervened in May 2017 due to metastasis of right laterocervical squamous cell cancer with radical emptying.
The patient presented secondary neuralgia of the upper alveolar branch of the second right trigeminal branch with food stimuli, of short duration and high intensity.
Treatment with gabapentin 300 mg is started every 8 hours with excessive sedation. Likewise, the patient does not tolerate any opioid. Post-treatment with carbamazepine 200 mg is started every 8 hours without adverse effects but with little analgesic response. Due to the tumor infiltration, any approach of the Gasser ganglion is rejected, opting for infiltration with botulinum toxin. 
25 units of supracigomatic botulinum toxin are infiltrated, 25 infracigomatic units and 5 units in 9 trigger points in total in territory of I, II and III branch of V par.
Results: There were no adverse effects and the patient´s pain on the visual analog scale was 1/10.
Conclusions: botulinum toxin is a good analgesic alternative in trigeminal neuralgia resistant to oral treatment in a patient with significant comorbidity.

TREATMENT WITH BOTULINUM TOXIN IN A PATIENT WITH OROPHARYNGEAL CARCINOMA AND TRIGEMINAL NEURALGIA