Introduction: NPH is a reversible cause of dementia and gait dysfunction in the elderly. High volume lumbar drainage has been used to select patients for shunting. Predicting likelihood of cognitive improvement is challenging in this population. The authors considered whether hippocampal volumes (HV) are predictive of cognitive outcomes following shunting.
Methods: Patients with NPH who underwent VP shunt placement were retrospectively reviewed to consider HV as a predictor of clinical outcome. Assessment of HV was performed using volumetric measures derived from NeuroQuant and FreeSurfer. Measurements of cognitive and gait function prior to and following CSF diversion were assessed per our clinic standard. Patients were stratified based upon presurgical HV. Clinical outcomes were compared within the two groups
Results: 22 patients underwent VP shunt placement for NPH between May 2012 and November 2013 and had preoperative MRI with volumetric measures. 16 patients had abnormal HV (<1st percentile ADNI classification); 6 had normal HV. 4 patients with abnormal HV (25%) demonstrated cognitive improvement and 12 (75%) demonstrated no improvement or cognitive decline following shunting. 5 patients with normal HV (83%) demonstrated cognitive improvement and 1 (17%) demonstrated no improvement or cognitive decline. HV was associated with cognitive response to shunting (p=0.013). 9 patients with abnormal HV (56%) demonstrated improvement in gait and 7 (44%) demonstrated no improvement or a decline in their gait symptoms. 5 patients with normal HV (83%) demonstrated improvement in gait and 1 (17%) demonstrated no improvement in gait following surgery. This did not suggest a correlation between HV and gait improvement following shunting (p=0.23).
Conclusions: It is challenging to predict patients’ cognitive response to shunting for NPH. This preliminary analysis suggests that preoperative HV can help predict cognitive improvement. This suggests a benefit to further prospective assessment of HV as an imaging marker in NPH
Patient Care: This research identifies a potential imaging marker to be used to predict cognitive outcome following shunt placement for treatment of NPH. This represents a noninvasive tool that can be used in pre-operative counseling for patients undergoing surgical treatment of NPH.
Learning Objectives: By conclusion of this session, participants should be able to: 1) Describe the importance of volumetric measurements in predicting cognitive outcomes following CSF shunting of NPH patients 2) Consider using volumetric measurement of HV when counseling patients about possible surgical outcomes of shunting
References: 1. Savolainen S, Laakso MP, Paljärvi L, Alafuzoff I, Hurskainen H, Partanen K, Soininen H, Vapalahti M. MR imaging of the hippocampus in normal pressure hydrocephalus: correlations with cortical Alzheimer's disease confirmed by pathologic analysis. AJNR Am J Neuroradiol. 2000 Feb;21(2):409-14
2. Tarnaris A, Kitchen N, Watkins L. Nonivasive biomarkers in normal pressure hydrocephalus: evidence for the role of neuroimaging. J Neurosug. 2009 May; 110:837-851
3. Teipel S, Grothe M, Lista S, Toschi N, Garaci F, Hampel H. Relevance of magnetic resonance imaging for early detection and diagnosis of Alzheimer Disease. Med Clin N Am. 2013; 97: 339-424
4. Clifford J, Petersen R, Xu Y, O’Brien P, Smith G, Ivnik R, Boeve B, Waring S, Tangalos E, Kokmen E. Prediction of AD with MRI-based hippocampal volume in mild cognitive impairment. Neurology. 1999 April: 52 (7): 1397-1403
5. Relkin N, Marmarou A, Klinge P, Bergsneider M, Black PM. Diagnosing idiopathic normal-pressure hydrocephalus.Neurosurgery. 2005 Sep;57(3 Suppl):S4-16
6. Gallia G, Rigamonti D, Williams M. The diagnosis and treatment of idiopathic normal pressure hydrocephalus. Nature Clinical Practice Neurology. 2005 March; (2): 375-381