Rare Complications Of A Popular Procedure: A Multi-institutional Case Series of Superior Laryngeal Nerve Block (SLN)...

Superior laryngeal nerve (SLN) blocks have emerged as a minimally invasive treatment for various forms of laryngeal sensory neuropathy, including neurogenic cough, para-laryngeal pain, and globus sensation. This in-office injection is quick and generally well tolerated, with the occasional complications of injection site ecchymosis, discomfort, or transient laryngeal anesthesia previously described. Here, we present a multi-institutional case series of uncommon complications from SLN blocks.

A cohort of 16 laryngologists from 15 institutions were polled for SLN block complications. Ten laryngologists reported uncommon complications. Patient demographic data, comorbidities, indication for injection, and complication information was collected.

Thirteen patients with unusual complications after SLN block were recorded. These included: marginal mandibular nerve palsy (5), fungal pharyngitis of the pyriform sinus (2), transient ischemic attack (2), Horner syndrome, anxiety-related response, adrenal suppression, and hypoglossal palsy. Eight patients were female with an average age of 57.2. On the Clavien-Dindo Scale of surgical complications, only those with fungal pharyngitis or adrenal suppression were scored above grade I, as they required specific pharmacological treatment (grade II).

SLN block is typically a well-tolerated procedure with minimal risks. In this case series, the most frequently reported events were caused by medication interactions with nearby nerves, including the marginal mandibular nerve producing a self-resolving palsy, and the sympathetic chain causing transient Horner's syndrome. As this injection is increasingly performed, we anticipate more reports of these or other uncommon complications in the future, which should be discussed during the consent process.