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Transcranial Doppler pulsatility index: not an accurate method to assess intracranial pressure.
Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Neurologi.
Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Neurologi.
Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Neurologi.ORCID-id: 0000-0001-6451-1940
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2010 (Engelska)Ingår i: Neurosurgery, ISSN 0148-396X, E-ISSN 1524-4040, Vol. 66, nr 6, s. 1050-1057Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

BACKGROUND: Transcranial Doppler sonography (TCD) assessment of intracranial blood flow velocity has been suggested to accurately determine intracranial pressure (ICP). OBJECTIVE: We attempted to validate this method in patients with communicating cerebrospinal fluid systems using predetermined pressure levels. METHODS: Ten patients underwent a lumbar infusion test, applying 4 to 5 preset ICP levels. On each level, the pulsatility index (PI) in the middle cerebral artery was determined by measuring the blood flow velocity using TCD. ICP was simultaneously measured with an intraparenchymal sensor. ICP and PI were compared using correlation analysis. For further understanding of the ICP-PI relationship, a mathematical model of the intracranial dynamics was simulated using a computer. RESULTS: The ICP-PI regression equation was based on data from 8 patients. For 2 patients, no audible Doppler signal was obtained. The equation was ICP = 23*PI + 14 (R = 0.22, P < .01, N = 35). The 95% confidence interval for a mean ICP of 20 mm Hg was -3.8 to 43.8 mm Hg. Individually, the regression coefficients varied from 42 to 90 and the offsets from -32 to +3. The mathematical simulations suggest that variations in vessel compliance, autoregulation, and arterial pressure have a serious effect on the ICP-PI relationship. CONCLUSIONS: The in vivo results show that PI is not a reliable predictor of ICP. Mathematical simulations indicate that this is caused by variations in physiological parameters.

Ort, förlag, år, upplaga, sidor
2010. Vol. 66, nr 6, s. 1050-1057
Nyckelord [en]
Blood flow velocity, hydrocephalus, intracranial pressure, middle cerebral artery, pulsatility indix
Nationell ämneskategori
Medicin och hälsovetenskap
Identifikatorer
URN: urn:nbn:se:umu:diva-34863DOI: 10.1227/01.NEU.0000369519.35932.F2ISI: 000278006200018PubMedID: 20495421OAI: oai:DiVA.org:umu-34863DiVA, id: diva2:326183
Tillgänglig från: 2010-06-22 Skapad: 2010-06-22 Senast uppdaterad: 2018-06-08Bibliografiskt granskad
Ingår i avhandling
1. Measurements in Idiopathic Normal Pressure Hydrocephalus: Computerized neuropsychological test battery and intracranial pulse waves
Öppna denna publikation i ny flik eller fönster >>Measurements in Idiopathic Normal Pressure Hydrocephalus: Computerized neuropsychological test battery and intracranial pulse waves
2014 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

Idiopathic Normal Pressure Hydrocephalus (INPH) is a condition affecting gait, cognition and continence. Radiological examination reveals enlarged ventricles of the brain. A shunt that drains CSF from the ventricles to the abdomen often improves the symptoms. Much research on INPH has been focused on identifying tests that predict the outcome after shunt surgery. As part of this quest, there are attempts to find measurement methods of intracranial parameters that are valid, reliable, tolerable and safe for patients.

Today's technologies for intracranial pressure (ICP) measurement are invasive, often requiring a burr-hole in the skull. Recently, a method for non-invasive ICP measurements was suggested: the Pulsatile Index (PI) calculated from transcranial Doppler data assessed from the middle cerebral artery. In this thesis the relation between PI and ICP was explored in INPH patients during controlled ICP regulation by lumbar infusion. The confidence interval for predicted ICP, based on measured PI was too large for the method to be of clinical utility.

In the quest for better predictive tests for shunt success in INPH, recent studies have shown promising results with criteria based on cardiac related ICP wave amplitudes. The brain ventricular system, and the fluid surrounding the spinal cord are in contact. In this thesis it was shown that ICP waves could be measured via lumbar subarachnoid space, with a slight underestimation.

One of the cardinal symptoms of hydrocephalus is cognitive impairment. Neuropsychological studies have demonstrated cognitive tests that are impaired and improve after shunt surgery in INPH patients. However, there is currently no standardized test battery and different studies use different tests. In response, in this thesis a fully automated computerized neuropsychological test battery was developed. The validity, reliability, responsiveness to improvement after shunt surgery and feasibility for testing INPH patients was demonstrated. It was also demonstrated that INPH patients were impaired in all subtests, compared to healthy elderly. 

Ort, förlag, år, upplaga, sidor
Umeå: Umeå universitet, 2014. s. 67
Serie
Umeå University medical dissertations, ISSN 0346-6612 ; 1689
Nyckelord
Hydrocephalus, Normal Pressure; Neuropsychological tests; Neuropsychology; Reliability and validity; Software; Dementia; intracranial pressure; spinal puncture; cerebrospinal fluid pressure; pulse pressure waves; Blood flow velocity; Middle cerebral artery; Pulsatility index
Nationell ämneskategori
Medicin och hälsovetenskap
Forskningsämne
neurologi
Identifikatorer
urn:nbn:se:umu:diva-96195 (URN)978-91-7601-155-3 (ISBN)
Disputation
2014-12-05, Sal E04 Unod R1, Umeå, 13:00 (Svenska)
Opponent
Handledare
Tillgänglig från: 2014-11-14 Skapad: 2014-11-12 Senast uppdaterad: 2018-06-07Bibliografiskt granskad

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Behrens, AndersLenfeldt, NiklasAmbarki, KhalidMalm, JanEklund, AndersKoskinen, Lars-Owe

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