An Unexpected Complication by Misplacement of an External Ventricular Drain; Transient Oculomotor Palsy Due to Direct Compression by a Drain—A Case Report

Background: Insertion of an external ventricular drain (EVD) is an important neurosurgical technique. There is a minor risk of misplacement, and complications including infections or hemorrhages have been reported. Transient neurological complications are, however, very rare, especially when EVD is placed under endoscope assistance. We report a case of unilateral transient oculomotor palsy after an EVD procedure. Case presentation: An 11-year-old boy with past medical history of moyamoya disease suffered from intraventricular hemorrhage and acute hydrocephalus. Insertion of EVD and hematoma removal was performed with endoscope assistance. After the surgery, transient oculomotor palsy occurred by the direct compression of the brain stem by the drainage tube. Conclusion: Transient unilateral oculomotor palsy due to the direct compression of the midbrain by an EVD tube is a very rare, but possible complication, even under endoscopic assistance. Attention through the procedure is required until skin closure to avoid tube dislocation.