Objective: To determine the prevalence of neurodegenerative disorders in idiopathic normal pressure hydrocephalus (iNPH) and their effects on the clinical features of iNPH.

Background: To establish the diagnosis of iNPH can be challenging because the clinical symptoms are similar to neurodegenerative disorders like Alzheimer’s disease (AD)1.  Some studies have reported concomitant presence of neurodegenerative disorders in patients with iNPH, but their prevalence and effects on the clinical manifestations and consequence of LP shunt surgery remain undetermined.

Method: We retrospectively analyzed patients who have hospitalized in the department of Neurology, Juntendo University School of Medicine past ten years. This study includes iNPH patients who fulfilled the criteria of Probable iNPH in the Clinical Guidelines for iNPH2, Parkinson’s disease (PD) patients who fulfilled the criteria of clinically established PD in the MDS-PD criteria with small modifications3, Lewy body dementia (DLB) patients who fulfilled the criteria of probable DLB in the DLB Consortium at the Degree of Lewy bodies Fourth consensus report4, progressive supranuclear palsy (PSP) patients who fulfilled the criteria of Probable PSP in the MDS-PSP criteria5, AD patients who fulfilled the criteria of AD in the National Institute Aging-Alzheimer Association Workgroup6.

Results: Sixty-seven patients are met the criteria of iNPH. Among them, 33 patients also have other neurodegenerative disorders (iNPHwith) including 18 PD (27%), 8 PSP (12%), 5 DLB (7%) and 3 AD patients (4%). Remaining 34 patients (49%) developed iNPH without accompanying neurodegenerative disorders (iNPHonly). There are several differences in clinical features between iNPHwith and iNPHonly.  First, the mean onset age of iNPHwith PD tends to younger than the remaining other groups (p = 0.65). Second, iNPHwith PD and DLB show a decrease in 123I-ioflupan SPECT accumulation in striatum (p < 0.01).  Third, iNPHwith AD and DLB show lower MMSE (Minimum State Examinations) scores (p < 0.01). Finally, while iNPHonly consistently improves after LP shunt surgeries, the iNPHwith patients show transient improvements after surgeries.

Conclusion: Our results illustrate that iNPH are often associated with neurodegenerative disorders, and coexisting these diseases affect clinical features of iNPH and most importantly, may limit the benefit of shunt surgeries.

References: 1. Gallia GL, Rigamonti D, Williams MA. The diagnosis and treatment of idiopathic normal pressure hydrocephalus. Nat Clin Pract Neurol 2006;2(7):375-381. 2. Relkin N, Marmarou A, Klinge P, Bergsneider M, Black PM. Diagnosing idiopathic normal-pressure hydrocephalus. Neurosurgery 2005;57(3 Suppl):S4-16; discussion ii-v. 3. Marsili L, Rizzo G, Colosimo C. Diagnostic Criteria for Parkinson’s Disease: From James Parkinson to the Concept of Prodromal Disease. Front Neurol 2018;9:156. 4. McKeith IG, Boeve BF, Dickson DW, et al. Diagnosis and management of dementia with Lewy bodies: Fourth consensus report of the DLB Consortium. Neurology 2017;89(1):88-100. 5. Hoglinger GU, Respondek G, Stamelou M, et al. Clinical diagnosis of progressive supranuclear palsy: The movement disorder society criteria. Mov Disord 2017;32(6):853-864. 6. McKhann GM, Knopman DS, Chertkow H, et al. The diagnosis of dementia due to Alzheimer’s disease: recommendations from the National Institute on Aging-Alzheimer’s Association workgroups on diagnostic guidelines for Alzheimer’s disease. Alzheimers Dement 2011;7(3):263-269.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/the-effect-of-coexistent-neurodegenerative-disorders-on-the-clinical-features-of-idiopathic-normal-pressure-hydrocephalus/