Transient headache and neurological deficits with cerebrospinal fluid lymphocytosis (HaNDL) is an uncommon disorder described in 1981 by Bartleson et al. Current diagnostic criteria (ICHD-III beta version 7.3.5) consider episodes of moderate or severe headache, lasting hours and associating cerebrospinal fluid (CSF) pleocytosis with lymphocytic predominance [1]. Neuroimaging studies and CSF culture are required to be normal.Neurological deficits [2] more commonly reported are sensory symptoms (78 % of cases), aphasia (66 %), and motor weakness (41 %). In addition to these symptoms, other features as elevation of CSF proteins [2] have also been described.To draw attention to this potentially misdiagnosed disorder, our aim is to report a case of headache and transient neurological deficits with a severe cerebral perfusion disturbance and the absence of CSF lymphocytosis.A 15-year-old male with a prior history of migraine was admitted to emergency department due to a non-fluent aphasia and sensory and motor deficit in right limbs of 40 min of evolution. He described a severe stabbing headache starting in right fronto-parietal scalp associating phonophobia and photophobia. A cerebral unenhanced and perfusion computed tomography (CT) was performed, while headache and a mild sensory disturbance in his right limbs were still present. Unenhanced CT was normal, but perfusion CT revealed an increased mean transit time (MTT) and a diminished cerebral blood flow (CBF) throughout the entire left cerebral hemisphere not confined to a particular vascular territory (Fig.