Clinical and Cognitive Features of Idiopathic Normal Pressure Hydrocephalus

Abstract

Introduction: Idiopathic normal pressure hydrocephalus (iNPH) is characterized by dilated cerebral ventricles with progressive impaired gait, cognition, and urinary control. Firstly described in 1965 by Hakim and Adam, it remains largely under-diagnosed. The diagnosis is based on clinical and imaging (CT or MRI) investigations; a timely diagnosis and cerebrospinal fluid (CSF) shunt surgery has reported to be beneficial in 60 up to 80% of the cases. Body: The severity of motor and cognitive disturbances varies widely and it can be difficult to distinguish iNPH from other neurodegenerative disorders. The cognitive and behavioral disturbances have been commonly described as "fronto-subcortical dysfunction". However, this definition is reductive not encompassing the entire cognitive spectrum of iNPH deficits. In our sample we found an impairment in respect to healthy controls in all the neuropsychological tests, but verbal memory. We could also find a positive correlation between the severity of cognition deficit and disease progression, suggesting a common pathological mechanism. Conclusions: iNPH can be reliably diagnosed with an organized approach. Neurologists play an essential role in the care of patients and a multidisciplinary team can improve this process. An early shunt surgery might contain the progression of the disturbances and also possibly prevent their development.

Phasic alertness and working memory improvements following lumbar puncture in iNPH patients differ from other age-associated cognitive syndromes.

“…In contrast to vascular dementia, iNPH causes the greater reduction of memory functioning; in comparison to Lewy body dementia, visuospatial abilities are less affected in iNPH (Durand et al, 2020; Gallassi et al, 1991; Table 1). While the involvement of frontal lobe dysfunction in iNPH-related memory deficits is still under debate (Walchenbach et al, 2002), the significance of visuoperceptual and visuospatial deficits demonstrates that the often cited term “frontosubcortical dementia” does not sufficiently describe the cognitive profile observed in iNPH (Sinforiani et al, 2018).…”

“…For assessment, Japanese guidelines recommend the Mini-Mental State Examination, the Wechsler Adult Intelligence Scale-III (WAIS-III) (digit symbol coding), WAIS-III (symbol search tasks), the Frontal Assessment Battery, and the Rivermead Behavioral Memory Test (Nakajima et al, 2021). The neuropsychological profile in iNPH was reported to include deficits in attention, concentration, executive function, working memory, recall memory, and visuoperceptual and visuospatial skills, whereas practical and language functions are often described to be relatively unimpaired (Isaacs et al, 2019; Sinforiani et al, 2018). Domain-specific severity of cognitive impairments, also in comparison with other causes of cognitive decline, might facilitate the identification of iNPH and is shown in Table 1.…”