Table 5.

Intracranial pressure monitoring

Study	Shunted patients	Methodology	Criteria for SR	Side effects	Main reported outcomes
Stephensen et al. (2005) [62]	n = 13	• Assessments: gait, balance, social function, climbing stairs, psychometric test • Overnight intraparenchymal ICPM (17 to 26 h) at 50 Hz (B-wave analysis) 1-day pre-shunting • Follow-up: 3–6 months	• Mean of difference between results from preoperative and postoperative test battery, > 0 implies improvement	• Not reported	• B-waves were seen in all NPH patients • No significant correlation between percentage of B-waves and post-shunting outcomes were found
Mahr et al. (2016) [37]	n = 31	• Assessments: Kiefer score, SLHS, MMSE, standardized gait testing, grooved pegboard test, and mRS • Overnight intraparenchymal ICPM was used for 24–48 h • Follow-up: 12 months	• Excellent (relief of all symptoms) • Improved (Kiefer score reduction of at least 10%)	• 1 patient experienced temporary neurological deficit, 2 patients were non-compliant	• RAP index, mean ICP, and slow wave amplitude did not differ significantly between shunt responders and non-responders • RAP > 0.8 shunt outcome prediction: sensitivity = 74%, specificity = 70%; PPV = 61%, NPV = 81% • RAP < 0.7 shunt outcome prediction: sensitivity = 91%, specificity = 41%; PPV = 55%, NPV = 86% • Slow wave > 1.5 shunt outcome prediction: sensitivity = 35%, specificity = 71%; PPV = 80%, NPV = 25% • TP = 9, FN = 3, FP = 6, TN = 14
Garcia-Armengol et al. (2016) [20]	n = 89	• Assessments: NPH score, MRI (DESH) • Overnight intraparenchymal ICPM (10 h) 1-day pre-shunting • Follow-up: 12 months	• Improvement in NPH score	• Not reported	• High ICP pulse amplitude (> 4 mmHg) was significantly more prevalent among shunt responders (84.4%) than non-responders (12%), p < 0.001 • ICP pulse amplitude > 4 mmHg: Youden index = 0.72, PPV = 94.7% and NPV = 68.8% • ICP pulse amplitude was more sensitive (84.4% vs 79.7%) and more specific (88.0% vs 80.0%) than a positive DESH finding in predicting SR • TP = 54, FN = 10, FP = 3, TN = 22
Sorteberg et al. (2004) [61]	n = 15	• Assessments: NPH score (including gait disturbance, urinary incontinence, and dementia) • Intraparenchymal ICPM was used for 24 h • Follow-up: 6 months	• Post-shunt increases in NPH score relative to baseline	• Not reported	• No relationship between the number of ICP elevations to 20 mmHg (lasting 0.5 or 1 min) and SR • No significant relationship between mean ICP and SR
Eide et al. (2010) [18]	n = 27	• Assessments: NPH grading scale (gait disturbance, urinary incontinence, and dementia) • Intraparenchymal ICPM and ABP monitoring • Software computed mean ABP, mean ICP, mean ABP wave amplitude, mean ICP wave amplitude, and cerebral perfusion pressure (CPP) measured in 6-s time windows • Shunt insertion 1–3-week post-assessment • Follow-up: 3, 6, 12 months	• Increase ≥ 2 scores on NPH scale	• Not reported	• Mean ICP wave amplitude was significantly increased in shunt responders compared with non-responders (p < 0.001) • Compared to other parameters (static ABP, static ICP), mean ICP wave amplitude (≥ 4 mm Hg) was highly predictive for SR (PPV = 100% and NPV = 100%) • TP = 21, FN = 0, FP = 0, TN = 6
Eide and Stanisic (2010) [17]	n = 31	• Assessments: NPH grading score • Continuous overnight intraparenchymal ICPM • Criteria for increased intracranial pulsatility: mean ICP wave amplitude ≥ 4 mm Hg on average in addition to mean ICP wave amplitude ≥ 5 mmHg in 10% of recording time • Follow-up: 3 and 6–12 months	• Increase of ≥ 2 scores on the NPH scale	• Not reported	• 95.8% patients with high pulsatile ICP were shunt responsive • Pulsatile ICP was significantly higher (p < 0.001) in shunt responders than non-responders • TP = 23, FN = 1, FP = 1, TN = 6 • Pulsatile ICP (mean ICP wave amplitude) was significantly correlated with NPH score (Spearman correlation − 0.47; p = 0.002) • Only 14.3% of patients with low pulsatile ICP were shunt responsive • ICP pulsatility: PPV = 96% and NPV = 86%
Pfisterer et al. (2007) [51]	n = 55	• Assessments: Dutch classification • Invasive CIPM was used for 48 h • ICP abnormally high: continuously > 10 mmHg • Positive ICPM: B-waves between 5 and 10% • Follow-up: 1 to 10 years (median 6.5 years)	• Improvement in gait/cognition/urinary incontinence on an ordinary scale using the Dutch classification	• 1 patient suffered from acute ventriculitis	• Positive CIPM followed by shunt insertion correlated with a significant improvement of gait (96.1%), memory (77.1%), and urinary disturbance (75.7%) (p < 0.004) • Patients with pressure levels > 10 mmHg improved following shunting (p < 0.01) • No significant relationship between B-wave amplitude and SR
Eide (2005) [13]	n = 39	• Assessments: NPH grading scale • Continuous intraparenchymal ICPM • The percentage time the mean ICP wave amplitude was ≥ 2 mmHg, ≥ 3 mmHg, ≥ 4 mmHg, ≥ 5 mmHg, ≥ 6 mmHg, or ≥ 7 mmHg was recorded within cconsecutive 6-s time windows during a 10-h recording • Follow up: 12 months	• An increase of ≥ 1 point in NPH score	• Not reported	• Mean ICP or ICP wave latency did not differ between shunt responders and non-responders • Mean ICP wave amplitude was significantly different between the groups (p < 0.001) • Mean ICP wave amplitude was significantly higher (p < 0.001) in those with a ≥ 1-point change in NPH score compared to those who did not • Mean ICP wave amplitude of ≥ 4 mmHg in 70% of time windows: PPV = 90% and NPV = 100% • Mean ICP wave amplitude of ≥ 5 mmHg in 40% of time windows: PPV = 89% and NPV = 91% • TP = 32, FN = 0, FP = 1, TN = 16
Eide and Brean (2006) [14]	n = 23	• Assessments: NPH grading scale • Intraparenchymal ICP monitoring • Elevated ICP amplitudes: when mean wave amplitudes were either ≥ 4 mmHg in ≥ 70%, ≥ 5 mmHg in ≥ 40%, or ≥ 6 mmHg in ≥ 10% of the recording time • Follow up: 12 months	• Increase in NPH score	• Minor complications in 4 patients (6.5%)—subcutaneous wound infections (treated with antibiotics)	• 91% of patients with elevated mean wave amplitudes (> 2 mmHg) demonstrated a marked improvement (median change in NPH score + 4) • Ranges of SR prediction of the threshold values: PPV = 82–90% and NPV = 91–100%
Eide (2011) [12]	n = 22	• Assessments: NPH grading scale • Overnight intraparenchymal ICPM, CO, and ABP wave amplitude monitoring • Elevated ICP wave amplitudes: average of mean ICP wave amplitude ≥ 4 mmHg in addition to mean ICP wave amplitude ≥ 5 mmHg in ≥ 10% of time recording • Follow up: 12 months	• An increase ≥ 2 in NPH score	• Not reported	• NPH score did not correlate to the CO and to ABP wave amplitude but correlated significantly to ICP wave amplitude (p = 0.003) • Patients with higher preoperative ICP wave amplitude levels showed greater improvement in iNPH symptoms at 12-month follow-up • Elevated ICP wave amplitude: sensitivity = 100%, specificity = 50% • TP = 16, FN = 0, FP = 3, TN = 13
Eide and Sorteberg (2010) [16]	n = 131	• Assessments: NPH grading scale • Intraparenchymal continuous ICPM • Abnormal intracranial pulsatility: average mean ICP of > 4 mmHg in addition to mean ICP wave amplitude of > 5 mmHg in > 10% of time recordings, in 6-s time windows • Follow-up: from 3 months (2-year median)	• An increase ≥ 2 in NPH score	• Not reported	• Threshold of mean ICP (8 mmHg): sensitivity = 51%, specificity = 74%, PPV = 88%, and NPV = 28% • Mean ICP wave amplitude ≥ 4 mmHg: sensitivity = 98%, specificity = 70%, PPV = 93%, and NPV = 91% • Mean ICP wave rise time coefficient threshold of 20 mmHg/s: sensitivity = 74%, specificity = 74%, PPV = 92%, and NPV = 43% • RAP threshold of 0.8: sensitivity = 66%, specificity = 48%, PPV = 82%, and NPV = 27% • TP = 100, FN = 2, FP = 8, TN = 20

Studies included assessing the use of intracranial pressure monitoring (ICPM) in predicting shunt responsiveness. CT, computerized tomography; MRI, magnetic resonance imaging; ICP, intracranial pressure; ABP, arterial blood pressure; ICPM, ICP monitoring; SLHS, Stein and Langfitt hydrocephalus score; MMSE, mini mental state exam; mRS, modified Rankin scale; LIFT, lumbar infusion test; CIPM, continuous ICPM; ELD, extended lumbar drainage; RAP, correlation coefficient between pulse amplitude and ICP; DESH, disproportionately enlarged subarachnoid space hydrocephalus; NPH, normal pressure hydrocephalus; INPH, idiopathic NPH.