The syndrome of headache with neurologic deficits and cerebrospinal fluid lymphocytosis (HANDL) is rare; it comprises migrainous headaches (generally in headache-naïve people), fluctuating neurological symptoms and cerebrospinal fluid (CSF) lymphocytosis. The syndrome generally runs a benign, self-limiting course over weeks. A small proportion of patients develop intracranial hypertension as a consequence of the illness. Recurrence of headaches or development of visual symptoms following apparent recovery from HANDL should prompt urgent re-evaluation for elevated intracranial pressure. Short-to-medium term management with CSF drainage and acetazolamide may be necessary to prevent visual loss.