Are the Comments on HaNDL Syndrome in the ICHD-II Sufficient?

A 33-year-old man was admitted to our emergency department for severe frontal headache followed by a state of consciousness disturbance and right-sided hemiparesis. No previous febrile disease, head trauma, vascular risk factor, and medication for any systemic disease were defined in his history. He had experienced a similar disorder three years ago and had recovered completely. Cerebrospinal fluid (CSF) analysis revealed pleocytosis and electroencephalography (EEG) showed diffuse slow wave activity. Hyperintense foci on T2 and FLAIR sequences representing bilateral cortical ischemia, prominent on the right hemisphere, were seen on MRI. Contrast-enhanced T1 images showed marked leptomeningeal thickening with enhancement. The patient was considered as having CSF lymphocytosis (HaNDL syndrome) due to temporary headache with neurologic deficit and CSF pleocytosis. Diagnostic criteria have been identified for this syndrome according to the International Classification of Headache Disorders, 2^nd edition (ICHD-II). According to these criteria, neuroimaging should be normal. Positive neuroimaging findings and impairment of consciousness have been reported in a limited number of HaNDL cases so far. Diversity of neurological signs, duration and distinctness from migraine headache have been described in comment section under the diagnostic criteria. Comments are inadequate in this regard.