Takuma Ohmichi1, Masaki Kondo1, Masahiro Itsukage1, Hidetaka Koizumi1, Shigenori Matsushima2, Nagato Kuriyama3, Kazunari Ishii4, Etsuro Mori5, Kei Yamada2, Toshiki Mizuno1, Takahiko Tokuda1,6. 1. Departments of1Neurology. 2. 2Radiology. 3. 3Epidemiology for Community Health and Medicine, and. 4. 6Molecular Pathobiology of Brain Diseases, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto. 5. 4Department of Radiology, Kindai University Faculty of Medicine, Osaka; and. 6. 5Department of Behavioral Neurology and Cognitive Neuroscience, Tohoku University Graduate School of Medicine, Sendai, Japan.
Abstract
OBJECTIVE: The gold standard for the diagnosis of idiopathic normal pressure hydrocephalus (iNPH) is the CSF removal test. For elderly patients, however, a less invasive diagnostic method is required. On MRI, high-convexity tightness was reported to be an important finding for the diagnosis of iNPH. On SPECT, patients with iNPH often show hyperperfusion of the high-convexity area. The authors tested 2 hypotheses regarding the SPECT finding: 1) it is relative hyperperfusion reflecting the increased gray matter density of the convexity, and 2) it is useful for the diagnosis of iNPH. The authors termed the SPECT finding the convexity apparent hyperperfusion (CAPPAH) sign. METHODS: Two clinical studies were conducted. In study 1, SPECT was performed for 20 patients suspected of having iNPH, and regional cerebral blood flow (rCBF) of the high-convexity area was examined using quantitative analysis. Clinical differences between patients with the CAPPAH sign (CAP) and those without it (NCAP) were also compared. In study 2, the CAPPAH sign was retrospectively assessed in 30 patients with iNPH and 19 healthy controls using SPECT images and 3D stereotactic surface projection. RESULTS: In study 1, rCBF of the high-convexity area of the CAP group was calculated as 35.2–43.7 ml/min/100 g, which is not higher than normal values of rCBF determined by SPECT. The NCAP group showed lower cognitive function and weaker responses to the removal of CSF than the CAP group. In study 2, the CAPPAH sign was positive only in patients with iNPH (24/30) and not in controls (sensitivity 80%, specificity 100%). The coincidence rate between tight high convexity on MRI and the CAPPAH sign was very high (28/30). CONCLUSIONS: Patients with iNPH showed hyperperfusion of the high-convexity area on SPECT; however, the presence of the CAPPAH sign did not indicate real hyperperfusion of rCBF in the high-convexity area. The authors speculated that patients with iNPH without the CAPPAH sign, despite showing tight high convexity on MRI, might have comorbidities such as Alzheimer’s disease.
OBJECTIVE: The gold standard for the diagnosis of idiopathic normal pressure hydrocephalus (iNPH) is the CSF removal test. For elderly patients, however, a less invasive diagnostic method is required. On MRI, high-convexity tightness was reported to be an important finding for the diagnosis of iNPH. On SPECT, patients with iNPH often show hyperperfusion of the high-convexity area. The authors tested 2 hypotheses regarding the SPECT finding: 1) it is relative hyperperfusion reflecting the increased gray matter density of the convexity, and 2) it is useful for the diagnosis of iNPH. The authors termed the SPECT finding the convexity apparent hyperperfusion (CAPPAH) sign. METHODS: Two clinical studies were conducted. In study 1, SPECT was performed for 20 patients suspected of having iNPH, and regional cerebral blood flow (rCBF) of the high-convexity area was examined using quantitative analysis. Clinical differences between patients with the CAPPAH sign (CAP) and those without it (NCAP) were also compared. In study 2, the CAPPAH sign was retrospectively assessed in 30 patients with iNPH and 19 healthy controls using SPECT images and 3D stereotactic surface projection. RESULTS: In study 1, rCBF of the high-convexity area of the CAP group was calculated as 35.2–43.7 ml/min/100 g, which is not higher than normal values of rCBF determined by SPECT. The NCAP group showed lower cognitive function and weaker responses to the removal of CSF than the CAP group. In study 2, the CAPPAH sign was positive only in patients with iNPH (24/30) and not in controls (sensitivity 80%, specificity 100%). The coincidence rate between tight high convexity on MRI and the CAPPAH sign was very high (28/30). CONCLUSIONS:Patients with iNPH showed hyperperfusion of the high-convexity area on SPECT; however, the presence of the CAPPAH sign did not indicate real hyperperfusion of rCBF in the high-convexity area. The authors speculated that patients with iNPH without the CAPPAH sign, despite showing tight high convexity on MRI, might have comorbidities such as Alzheimer’s disease.
Entities:
Keywords:
123I-IMP = 123I-iodoamphetamine; 123I-IMP SPECT; ARG = autoradiography; CAP = patients with the CAPPAH sign; CAPPAH = convexity apparent hyperperfusion; CBF = cerebral blood flow; DESH = disproportionately enlarged subarachnoid space hydrocephalus; FAB = Frontal Assessment Battery; MMSE = Mini–Mental State Examination; NCAP = patients without the CAPPAH sign; ROI = region of interest; SEE = stereotactic extraction estimation; SSP = stereotactic surface projection; TMT-A = Trail Making Test A; TUG = Timed Up and Go; cerebral blood flow; convexity apparent hyperperfusion sign; iNPH = idiopathic normal pressure hydrocephalus; iNPHGS = iNPH Grading Scale; idiopathic normal pressure hydrocephalus; rCBF = regional CBF
Authors: Sauson Soldozy; Kaan Yağmurlu; Jeyan Kumar; Turki Elarjani; Josh Burks; Aria Jamshidi; Evan Luther; Kenneth C Liu; Carolina G Benjamin; Robert M Starke; Min S Park; Hasan R Syed; Mark E Shaffrey; Ricardo J Komotar Journal: Neurosurg Rev Date: 2021-11-13 Impact factor: 3.042