Table 4.
The clinical procedures for the diagnosis of idiopathic normal pressure hydrocephalus
| n | Procedure | Characteristic | Diagnostic findings | Remarks |
|---|---|---|---|---|
| 1 | CSF removal test/tap test | 30-50 ml CSF tap is performed via lumbar puncture in patient with VM | A positive response when there is improvement in the clinical symptoms. (Gait can be assessed quantitatively using the 3-m TUG test or the 10-m straight walk test)[30] | The mini-mental state examination, FAB, and/or trail-making tests are applied for the assessment of cognition[30] |
| FAB postdiagnostic CFSTT comparing responder and nonresponder | Higher preoperative FAB score in CFSTT responder (10.4±3.7) than nonresponder (7.6±4.4)[31] | There was association of FAB with the gait function suggesting similar circuits producing gait symptoms and frontal lobe functions in iNPH[31] | ||
| Logistic regression analysis using the FAB score as independent variable showed a significant influence of the FAB on the differential diagnosis of CSFTT responders and nonresponders (P=0.025; OR 1.186; 95% CI 1.022-1.377)[31] | ||||
| Finger tapping and verbal fluency post CSF tap test | Post-lumbar puncture amelioration of verbal fluency and finger tapping deficits in iNPH compared with nonneurocognitive improvement in iNPH-like group[32] | The test can be used to predict positive postshunt clinical outcome[32] | ||
| Simultaneous quantification of cognition and gait (dual task gait assessment and mental imagery of locomotion) before and 24 h after CSF tapping | Improvements seen in iNPH compared to iNPH mimics[1] | iNPH mimics (i.e., vascular dementia or other parkinsonian syndromes)[1] | ||
| Comparing cognitive impairment (iNPH-CI) and patients with iNPH and normal cognition, looking at gait improvement 2-4 h following STT | Significant improvement of gait parameters in patients without cognitive impairment following STT, but patients with iNPH-CI did not benefit from STT[33] | Further studies are needed to elucidate the associations of cognitive impairment and quantitative gait parameters measured early and at later time points after STT[33] | ||
| TUG and its iTUG after CSF tapping between iNPH and its mimics | Mental imagery of locomotion was modified after CSF tapping in iNPH patients, but not in the mimics[34] | The test before and after CSF tapping could help to identify iNPH patients from patients with similar neurological conditions[34] | ||
| A comparison of trunk sway was performed between HE and patients with various types of hydrocephalus VM | iNPH have significant higher trunk sway compared to HE in standing task, measured by body-worn gyroscopic system (P<0.001). If compared with VM, iNPH patients had significant lower sway velocity during gait (P<0.05). This sway velocity improved after CSF drainage[35] | The gyroscopic system quantitatively assessed postural deficits in iNPH[35] | ||
| ONSD between supine and upright positions ONSD-V before and after lumbar puncture | Mean prepuncture ONSD-V was significantly lower in healthy volunteers and patients with no response to CSF removal (Fisher’s test) (0.05 ± 0.14 mm [SD]) than in responsive patients (0.37 ± 0.20 mm [SD], P<0.001). The higher the ONSD-V, the better the therapeutic effect[36] | The ONSD-V before and after STT correlated well with the clinical effects of CSF removal[36] | ||
| 2 | SVW | Time-averaged signal strength was calculated over the full recording time (ICPS mean) and over the wave periods (ICPS) following ELD and ventriculoperitoneal shunting | Significant association between ICPS (P=0.014) and ICPS mean (P=0.022) with NPH[37] | Comparison between NPH patients and non-NPH patients[37] |
| 3 | CSF markers | The expression of hsa-miR-4274 in CSF in patients clinically diagnosed with iNPH, possible iNPH with PS, possible iNPH with AD, and nonaffected elderly individuals | The expression of hsa-miR-4274 in CSF was decreased in cohort of PS group patients (P<0.0001), and was able to distinguish PS from iNPH with high accuracy (area under the curve=0.908)[38] | A three-step qRT-PCR analysis of the CSF samples was performed to detect miRNAs that were differentially expressed in the groups[38] |
| PTPRQ in iNPH and AD patients | PTPRQ concentration in the CSF was significantly higher in patients with iNPH compared with those with AD | PTPRQ may be a useful biomarker for discriminating between patients with iNPH and AD, and may be a potential companion biomarker to identify SNRs among patients with iNPH[39] | ||
| The PTPRQ concentration in the CSF of nonresponders to shunt operation (SNRs) tended to be relatively lower compared with that in the responders[39] | ||||
| CSF proteins: Tf | Brain-type Tf levels decreased in iNPH compared with non-iNPH patients[40] | Brain-type Tf is a prognostic marker for recovery from dementia after shunt surgery for iNPH[40] | ||
| Brain-type Tf levels rapidly returned to normal levels within 1-3 months after shunt surgery in iNPH[40] | ||||
| 4 | The computer-aided intrathecal infusion test | The resistance to CSF outflow in the intrathecal infusion test with a constant-flow technique between NPH or those with cerebral atrophy | Resistance to CSF outflow correlated significantly with improvement (P<0.05).[41] Other markers such as amplitude in CSF pulse pressure, the slope of the amplitude-pressure regression line, or elasticity did not show any correlation with outcome[41] | A further differentiation into early stage and advanced stage was made by measuring the compliance[42] |
CSF – Cerebrospinal fluid; FAB – Frontal assessment battery; CSFTT – CSF fluid tap test; OR – Odds ratio; CI – Confidence interval; NPH – Normal pressure hydrocephalus; iNPH – Idiopathic NPH; STT – Spinal tap test; TUG – Timed Up and Go; iTUG – Imagined version TUG; HE – Healthy elderly; VM – Ventriculomegaly; ONSD – Optic nerve sheath diameter; ONSD-V – ONSD variability; ELD – External lumbar drainage; PS – Parkinsonian spectrum; AD – Alzheimer’s disease; PTPRQ – Protein tyrosine phosphatase receptor type Q; qRT-PCR – Real-time quantitative reverse transcription polymerase chain reaction; ICP – Intracranial pressure; Tf – Transferrin; SVW – Slow vasogenic ICP wave; SD – Standard deviation; ICPSmean – ICP over the full recording time; ICPS – ICP over the wave periods; SNRs – Shunt non-responders