**Author details**

degree, out of not demented patients, only 24% was characterized by fronto-cortical dysfunction and we also found a subgroup with impairment in a single cognitive domain and even

Therefore our results are in agreement with the data of the literature about a wide range of cognitive pictures in iNPH [50, 63–65, 94]; in particular, the heading of "fronto-subcortical dysfunction" is reductive as it cannot completely encompass the different cognitive profiles. The second important finding of our study is represented by a positive correlation between cognition and disease progression; in fact, though cognitive impairment may be absent in early cases, its severity undoubtedly increases with older age, disease duration and severity of motor disturbances, hypothesizing an underlying common physiopathological mechanism. In this view, as our data can suggest, an early shunt surgery could contain not only the progression of motor disturbances but also the advance of cognitive impairment in these

Our sample was enrolled on the basis of the presence of gait disturbances/parkinsonism and because of these symptoms the patients were referred to our Unit; this aspect may represent a weakness of the study in term of patient's enrollment. On the other hand it is well-known that

In this study, we have administered an exhaustive neuropsychological evaluation in order to investigate different cognitive domains; this is crucial to obtain a more detailed cognitive profile, as suggested by different authors [64–66]. In our opinion an accurate cognitive characterization before shunt is relevant in terms of outcome measures. Enrolling homogeneous population of iNPH may improve the prediction of response to shunt surgery; a longer follow-up period and a closer interaction among the different professionals are needed.

iNPH remains a complex and underestimated disease. As far cognitive impairment, this has commonly been described as fronto-subcortical dementia, but on the basis of the data of the literature we can assume that this term is reductive as it does not fully describe the different clinical pictures observed with an involvement of many other cognitive domains. Even after many years we still agree with the remarks of Iddon et al. in 1999 [50] "There may not be one single form of dementia syndrome in NPH but rather, there are varying degrees of cognitive change pre-shunt, according to the amount of permanent brain damage that has already taken place, compounded by comorbidity factors such as hypertensive cerebral small vessel disease". Undoubtedly, many other variables differently modulate and interfere with the disease expression. Moreover, an overlap with other neurodegenerative diseases can exist; this may be a complex and prognostic issue and could partly explain both the progression of cognitive decline and the absence of amelioration after successful CSF shunt procedures. With regard to the possible overlap with AD in particular, the weight of Alzheimer pathology in iNPH patients is not clear; studies investigating possible biological markers in fact have failed

patients without any neuropsychological deficit.

64 Hydrocephalus: Water on the Brain

motor disorders are the leading presentation of iNPH [1].

patients.

**9. Conclusions**

to obtain conclusive results.

Elena Sinforiani<sup>1</sup> \*, Claudio Pacchetti<sup>2</sup> , Marta Picascia2 , Nicolò Gabriele Pozzi2 , Massimiliano Todisco2 and Paolo Vitali3

\*Address all correspondence to: elena.sinforiani@mondino.it

1 Alzheimer's Disease Assessment Unit/Laboratory of Neuropsychology, C. Mondino National Neurological Institute, Pavia, Italy

2 Parkinson's Disease and Movement Disorders Unit, C. Mondino National Neurological Institute, Pavia, Italy

3 Neuroradiology Unit and Brain MRI 3T Mondino Research Center, C. Mondino National Neurological Institute, Pavia, Italy
