Normal Pressure Hydrocephalus with Primary Presentation of Psychiatric Disturbance?

I read with great interest the article by Kogan et al in which they describe a patient with normal pressure hydrocephalus (NPH) with a primary presentation of psychiatric disturbance.[1] The authors emphasize that their case was a unique example of NPH with primary symptoms of anxiety that might provide insight into similar future cases. I agree with the interesting aspect of the report. However, I would like to make some comments for a better understanding of the report and avoid some potentially misleading conclusions.

The initial admission of the patient was to a psychiatric hospital because of anxiety and belligerence, a remarkable point as described by the authors. But as I understand it, NPH was also suspected at that time, leading to a neurology consultation and the decision to perform a cerebrospinal fluid (CSF) tap test. However, large-volume CSF drainage was not performed initially, and no clinical improvement was noted. The association between the volume of CSF removed and the response to a tap test is controversial in the literature.[2] [3] However, diversion of a large volume of CSF during a tap test has been general knowledge for a long time.[4] In my opinion, in light of the presentation of this case, the significance of the amount of CSF drainage while interpreting the postdiversion response and making the diagnosis of NPH should have been described more specifically.

Second, I found the clinical description of the patient to be insufficient for a clear understanding of the clinical picture. Neuropsychiatric manifestations are common in NPH and may be present in up to 73% of patients.[5] In addition, after apathy, anxiety and aggression are the most common neuropsychiatric symptoms in patients with NPH.[5] However, interestingly the authors state the psychiatric manifestation of debilitating anxiety was so profound that the patient eventually required 24-hour supervision and assistance in activities of daily living (ADLs) before admission to their clinic. Remarkably, they state that informed consent was obtained from the patient and family. They also explain that the patient's degree of anxiety made the discussion of surgery and anesthesia very difficult.

Considering that the authors associate the significant disruption in ADLs with anxiety, I think they should have described that symptom in more detail. For example, what were the causes leading to the anxiety, was there an accompanying condition (panic disorders, depression, claustrophobia, etc.) leading to anxiety, and/or did they use a scale to measure the level of anxiety? The authors state that cognitive assessment with the Mini-Mental Status Examination was difficult because of the patient's severe anxiety and belligerence. However, no additional test was performed to elucidate the patient's cognitive profile. Frontal cognitive functions are known to be disturbed prominently in NPH, and their improvement following shunt surgery is typical.[6] [7] Neuropsychiatric manifestations including anxiety and aggression are frequently encountered in all dementia subtypes affecting frontal functions.

Taken together, I would say the involvement of cognitive impairment in the clinical picture as well as the improved function following shunt surgery were not clearly understood in this patient and may constitute a major limitation. Detailed documentation of the cognitive profile of the patient might have made a substantial contribution to our understanding of the clinical presentation. I think the main manifestation in this patient may have been the cognitive impairment, and the neuropsychiatric manifestations may have been one of the clinical manifestations of frontal type dementia (not the primary presentation). Clarification of these points might have provided a better understanding of the report as well as improving the mechanisms of shunt surgery.

• References

• 1 Kogan M, Agyei J, Cuddahee KJ, Gibbons KJ. Normal pressure hydrocephalus with primary presentation of psychiatric disturbance: case report. J Neurol Surg A Cent Eur Neurosurg 2019; 80 (05) 404-408
• 2 Thakur SK, Serulle Y, Miskin NP, Rusinek H, Golomb J, George AE. Lumbar puncture test in normal pressure hydrocephalus: does the volume of CSF removed affect the response to tap?. AJNR Am J Neuroradiol 2017; 38 (07) 1456-1460
• 3 Onder H, Hanalioglu S. Does the volume of CSF removed affect the response to a tap in normal pressure hydrocephalus?. AJNR Am J Neuroradiol 2018; 39 (01) E5-E6
• 4 Wikkelsø C, Andersson H, Blomstrand C, Lindqvist G. The clinical effect of lumbar puncture in normal pressure hydrocephalus. J Neurol Neurosurg Psychiatry 1982; 45 (01) 64-69
• 5 Kito Y, Kazui H, Kubo Y. , et al. Neuropsychiatric symptoms in patients with idiopathic normal pressure hydrocephalus. Behav Neurol 2009; 21 (03) 165-174
• 6 Saito M, Nishio Y, Kanno S. , et al. Cognitive profile of idiopathic normal pressure hydrocephalus. Dement Geriatr Cogn Disord Extra 2011; 1 (01) 202-211
• 7 Laidet M, Herrmann FR, Momjian S, Assal F, Allali G. Improvement in executive subfunctions following cerebrospinal fluid tap test identifies idiopathic normal pressure hydrocephalus from its mimics. Eur J Neurol 2015; 22 (12) 1533-1539