Background: The clinical syndrome of headache and neurological deficits and cerebrospinal fluid lymphocytosis (HaNDL) is recognized as a self-limiting condition consisting of discrete episodes of neurological deficit associated with moderate to severe headache. The spectrum of neurological features most commonly include aphasia, sensory, and motor disturbances. However, confusion and agitation has also been described. Case Presentation: We present an unusual case of a 28-year-old male with recurrent hospital presentations for headache, confusion, and other neurological stigmata over a period of 15 days, culminating in a diagnosis of HaNDL following extensive investigations. He was treated empirically for viral encephalitis initially; however, there were no positive results on virology screening. In addition, autoimmune screens were also negative. He was then managed symptomatically and discharged from hospital with resolution of symptoms thereafter. Conclusion: The differential diagnoses for transient acute confusional disorders remain expansive, with HaNDL being one of the many rare causes. Rigorous testing is required to exclude infective, inflammatory, ischemic, structural, or iatrogenic pathology, whil HaNDL primarily remains a diagnosis of exclusion.

Keywords: HaNDL, confusion, headache, behavioral changes, CSF lymphocytosis, neurological deficits.