Aetiologies of acquired pediatric sixth nerve palsies in a U.K. based population

Due to the low incidence of sixth cranial nerve palsies in children, there has been limited evidence published on this subject, especially from a population based within the UK. The incidence of etiologies has been found to vary significantly within the literature, especially with regard to neoplasms. The main aim of this study is to present the etiologies of newly diagnosed pediatric sixth nerve palsies in a UK-based population. We also take into consideration if the palsies were isolated or associated with other neurological signs or symptoms. Retrospective data collection was carried out on the medical records of 50 pediatric patients with a new-onset sixth nerve palsy. They all presented to a large tertiary referral hospital in the South of the UK between 1 January 2007 and 31 December 2017. Data collected for each patient included age, gender, ethnicity, unilateral versus bilateral, other signs and symptoms, etiology, where the patient first presented, and whether the palsy was the first presenting feature. Thirty-three (66%) patients had a new-onset sixth nerve palsy in conjunction with other neurological signs or symptoms and were considered non-isolated. Seventeen cases (34%) were found to be isolated. Etiologies included high intracranial pressure (18%), neoplasm (14%), surgery for neoplasm (14%), viral (14%), infection (12%), trauma (8%), idiopathic (6%), benign space-occupying lesion (4%), congenital (2%), inflammation (2%), Alexander's disease (2%), Kawasaki syndrome (2%), and diabetes (2%). Our study found non-isolated sixth nerve palsies to be the most common presentation. These patients had a high number of potentially sinister etiologies, the most common being high intracranial pressure followed by post-surgery for neoplasm and neoplasm. Isolated sixth nerve palsies were more commonly due to viral or idiopathic etiology; however, two cases of benign space-occupying lesion and one of neoplasm were identified.