Role of the Qst-Testing for the Determination of the Nervus Intermedius Neuralgia Phenotype – Case Report

Background and Objectives: Nervus Intermedius neuralgia is a rare and difficult to suspect entity. This study aims to present the case of intermedius neuralgia, discusses the implications of the phenotype in the patient approach, as well as the role of quantitative susceptibility testing (QST), as an important tool in the diagnosis and therapeutic management. Case report: 40-year-old female patient, smoker, accompanied by neurology (generalized tonic-clonic seizures), in use of carbamazepine. During one of the seizures, she said fall from height, resulting in fracture of the left temporal bone and ipsilateral facial paralysis. After to optimal the therapy, she had no more seizures, but evolved with paroxysmal pain, shock-like, located in the groove between the ear and scalp at high intensity, with shooting area in the wall of the external auditory channel. Reports that had more crisis with the arrival of winter. The examination revealed mechanical hyperalgesia and “wind-up” phenomenon on the affected side. CT mastoid with evidence of temporal fracture to the left crossing the mast cells. Electroneuromyography corroborating with peripheral facial paralysis. Other tests without changes. It was submitted to the QST-test, evidencing hyperalgesia to cold in the region corresponding to the pain complaint. Lamotrigine was associated with the treatment regimen with 90% improvement of symptoms. Conclusion: This is a rare etiology and difficult diagnosis. The QST-test was extremely important, as well as aid in the diagnosis also allows us to identify the great variability of phenotypic profile within each etiology, which may reflect distinct pathophysiological mechanisms, with different therapeutic responses. There is evidence that lamotrigine assist in the treatment of neuropathic pain associated hyperalgesia to cold.

Resumo

Justificativa e Objetivos:

A neuralgia do nervo intermediário é uma entidade rara e difícil de suspeitar.
Este estudo tem como objetivo apresentar o caso da neuralgia intermediária, discute as implicações do fenótipo na abordagem do paciente, bem como o papel dos testes quantitativos de suscetibilidade (QST), como uma importante ferramenta no diagnóstico e manejo terapêutico.

Relato de caso:
Paciente do sexo feminino, 40 anos, tabagista, acompanhada de neurologia (convulsões tônico-clônicas generalizadas), em uso de carbamazepina.
Durante uma das convulsões, ela relatou queda da própia altura, resultando em fratura do osso temporal esquerdo e paralisia facial ipsilateral. Após otimizar a terapia, ela não teve mais convulsões, mas evoluiu com dor paroxística, tipo choque, localizada no sulco entre orelha e couro cabeludo em alta intensidade, com área de projeção na parede do canal auditivo externo. Relata que teve mais crise com a chegada do inverno. O exame revelou hiperalgesia mecânica e fenômeno de “wind-up” no lado afetado. CT de mastóide com evidência de fratura temporal à esquerda cruzando os mastócitos. Eletroneuromiografia corroborando com paralisia facial periférica. Outros testes sem alterações. Foi submetido ao teste QST, evidenciando hiperalgesia a frio na região correspondente à queixa de dor. A lamotrigina foi associada ao regime de tratamento com melhora de 90% dos sintomas.

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