Diagnostic importance of disproportionately enlarged subarachnoid space hydrocephalus and Callosal Angle measurements in the context of normal pressure hydrocephalus: A useful tool for clinicians

Hydrocephalus is a clinical and neurologic condition characterized by an abnormal accumulation of cerebrospinal fluid (CSF). Currently, idiopathic Normal Pressure Hydrocephalus (iNPH) is recognized as a late-onset neurologic disorder defined by a clinical triad of gait disturbance, urinary incontinence, and dementia. Imaging studies often reveal a disproportionate increase in subarachnoid space and ventricular size relative to brain volume, with normal CSF pressure during lumbar puncture. Recent developments in neuroimaging have led to the establishment of criteria for diagnosing and managing iNPH, incorporating the concept of Disproportionately Enlarged Subarachnoid-space Hydrocephalus (DESH). Distinguishing iNPH from the natural neurological aging process and other forms of dementia, wherein brain atrophy and hydrocephalus ex vacuo can be observed, can present challenges for both neurologists and neuroradiologists. Despite DESH becoming a radiologic criterion for diagnosing iNPH in some guidelines, its recognition remains limited.