Prophylactic effect of topical diluted papaverine in preventing hearing loss during microvascular decompression for typical trigeminal neuralgia: Case report and technical note

Abstract

Background and objective: Papaverine hydrochloride is a direct-acting vasodilator used to manage vasospasm during various neurosurgical operations. Transient hearing loss due to vasospasm of Internal auditory artery during Posterior Fossa Microvascular Decompression (MVD) for Typical Trigeminal Neuralgia (TTN) is one of possible complications of this surgical procedure. The aim of this technical note is to underline the potential efficacy of the use of intracisternal diluted papaverine and its proper use. Materials and methods: BAEP is routinely used to monitoring functionality of vestibulocochlear nerve during MVD for TTN. In one patient recently operated on, during arachnoid dissection BAEP showed a lag of V wave of 1 ms, likely due to vasospasm of Internal Auditory Artery (IAA) probably caused by arachnoid traction. Intracisternal injection of pure papaverine without excipients (60 mg/2 ml) diluted in 20 cm3 of 0,9% saline solution (0,3%) was used as a direct therapeutic action to manage vasospasm of IAA artery. Results: Few minutes after the intracisternal injection of diluted papaverine, BAEP's wave V started to get back to normal length and at the end of procedure was the same evoked before starting MVD. After surgery hearing was bilaterally normal. Conclusions: There is large uncertainty about dose-related efficacy and side effects of intracisternal papaverine (iPPV). Dilution of papaverine in saline is recommended to avoid complications. In our practice, in line with the literature, we use 0,3% diluted pure papaverine to prevent hearing loss during MVD for TTN. Keywords: ABR, Hearing preservation, Microvascular decompression, Retrosigmoid approach, Trigeminal neuralgia