Regional cerebral blood flow in normal pressure hydrocephalus: diagnostic and prognostic aspects

Abstract

Relative regional cerebral blood flow (rrCBF) was measured by single-photon emission tomography (SPET), using technetium-99m-d,l-hexamethylpropylene amine oxime (HMPAO) as flow tracer, in 23 patients with normal pressure hydrocephalus (NPH). 1000 MBq 99mTc-HMPAO was given intravenously and the rrCBF calculated as regional/cerebellar count level ratios. The patients were examined before and 3-12 months after ventriculoperitoneal shunt surgery. rrCBF was also determined in ten healthy aged matched volunteers who served as controls. The NPH patients had decreased rrCBF in the hippocampal regions and in the frontal and parietal white matter as compared to the controls. The frontal/parietal rrCBF ratio correlated with both psychiatric disability and the preoperative degree of incontinence. Decreased flow in frontal white matter, frontoparietal and hippocampal grey matter and a low frontalparietal grey matter flow ratio preoperatively correlated with improvement in both Mini Mental State score and psychiatric disability after shunt surgery. After shunt surgery the rrCBF increased in the mesencephalon, frontal grey and white matter, parietal white matter and hippocampus. The flow increase in hippocampal regions and frontal white matter correlated with improvement in psychiatric symptomatology. The results of this study regarding the frontal and hippocampal rrCBF patterns, and the clinical correlation, support the hypothesis that CBF changes in these regions are of pathophysiological and prognostic importance in NPH.

Guidelines for Management of Idiopathic Normal Pressure Hydrocephalus Guidelines From the Guidelines Committee of Idiopathic Normal Pressure Hydrocephalus, the Japanese Society of Normal Pressure Hydrocephalus

“…82) There are few studies supporting the correlation between reduced flow and degree of symptoms. 57) There are many studies showing an association between improved symptoms and increased CBF after shunt procedure, 54B,70,74,118,128) but the contradictory result has been reported. 128) CSF tap test reveals no changes in CBF in normal controls, but some studies show an increase of CBF in NPH including iNPH.…”

“…86,87) Neurologically, bradykinesia, hypokinesia, paratonic rigidity, glabellar reflex, snout reflex, and palmomental reflex are exhibited with high frequency. 57,62) The combination of akinesia and tremor at rest is observed to a greater degree in iNPH than in sNPH. 50) Psychiatric symptoms are seen in 88% of cases of iNPH, 59) with easy fatigability, impatience, emotional instability, and drowsiness, and a tendency …”

“…These findings are supported by other studies. 57,70,74,76,117,128) A PET study reported the mean CBF decreased in the cerebrum and cerebellum with regional decrease in the basal ganglia and thalamus but not in the white matter. 82) There are few studies supporting the correlation between reduced flow and degree of symptoms.…”

Pathophysiology of Cerebral Circulatory Disorders in Idiopathic Normal Pressure Hydrocephalus

“…9,[12][13][14][17][18][19][20][21][22]24,[26][27][28][29]31,32,34) The results from reports on preoperative ischemic sites and postoperative sites of increased blood flow have varied, 13,17,19,20,22,24,26,27,31,32) however, and no firm consensus has been reached. In this study we use N-isopropyl-( 123 I)-P-iodoamphetamine single photon emission computed tomography ( 123 I-IMP SPECT) to compare the CBF and perfusion patterns of the cerebral cortex assessed by the three-dimensional stereotactic surface projection (3D-SSP) Z-score images at each site before and after surgery in iNPH cases effectively resolved by shunt intervention (shunt-effective cases).…”

Association of cerebrospinal fluid tap‐related oscillatory activity and shunt outcome in idiopathic normal‐pressure hydrocephalus

“…8 Previous single-photon emission computed tomography studies revealed that regional cerebral blood flow decreases in the frontal and temporal regions and increases after tap test and shunt operation. [9][10][11][12][13][14][15] However, white matter injuries resulted in structural cortical abnormalities, such as cortical thinning, in patients with iNPH. 16 Quantitative electroencephalogram (EEG) provides computerized imaging and statistical procedures to detect abnormal patterns in specific pathological conditions and normative features in several disorders.…”