Changes in cerebral blood flow velocity in patients with hypothyroidism

BackgroundAt present, hypothyroidism is a well-known risk factor for cardiovascular disorders. The aim of this study was to assess the effects of hypothyroidism on cerebral blood flow velocity with transcranial Doppler (TCD) ultrasonography.Design and methodsIn this study, 30 subjects were enrolled for clinical, subclinical, and healthy control groups. Bilateral middle cerebral artery (MCA) peak-systolic, end-diastolic, and mean blood flow velocities; Gosling's pulsatility index values; and Pourcelot's resistance index values were recorded and compared with each other. TCD was performed in clinical hypothyroid patients after they became euthyroid with thyroid hormone replacement therapy (HRT). The initial and post-HRT results for the clinical hypothyroid group were then compared and evaluated.ResultsThere were 30 subjects in each group. Men/women ratio and mean age in clinical hypothyroid, subclinical hypothyroid, and control groups were 3/27, 4/26, and 5/25, and 37.4, 34.4, and 36.7 respectively. Peak-systolic, end-diastolic, and mean blood flow velocities of bilateral MCA were similar in clinical and subclinical hypothyroid groups but significantly higher when compared with the control group. After adequate thyroid HRT in clinical hypothyroid group, the peak-systolic, end-diastolic, and mean blood flow velocities were significantly decreased.ConclusionsIncreased cerebral blood flow velocities were observed in clinical and subclinical patients with hypothyroidism. The normalization of increased blood flow velocity with thyroid HRT suggests a reversible condition.

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HOBOE (Head-of-Bed Optimization of Elevation) Study: Association of Higher Angle With Reduced Cerebral Blood Flow Velocity in Acute Ischemic Stroke

Physical Therapy ◽

10.2522/ptj.20100271 ◽

2011 ◽

Vol 91 (10) ◽

pp. 1503-1512 ◽

Cited By ~ 24

Author(s):

Abigail Jade Hunter ◽

Suzanne J. Snodgrass ◽

Debbie Quain ◽

Mark W. Parsons ◽

Christopher R. Levi

Keyword(s):

Blood Flow ◽

Cerebral Blood Flow ◽

Ischemic Stroke ◽

Flow Velocity ◽

Blood Flow Velocity ◽

Cerebral Blood Flow Velocity ◽

Mean Flow ◽

Study Association ◽

Blood Flow Velocities ◽

Flow Velocities

BackgroundCerebral autoregulation can be impaired after ischemic stroke, with potential adverse effects on cerebral blood flow during early rehabilitation.ObjectiveThe objective of this study was to assess changes in cerebral blood flow velocity with orthostatic variation at 24 hours after stroke.DesignThis investigation was an observational study comparing mean flow velocities (MFVs) at 30, 15, and 0 degrees of elevation of the head of the bed (HOB).MethodsEight participants underwent bilateral middle cerebral artery (MCA) transcranial Doppler monitoring during orthostatic variation at 24 hours after ischemic stroke. Computed tomography angiography separated participants into recanalized (artery completely reopened) and incompletely recanalized groups. Friedman tests were used to determine MFVs at the various HOB angles. Mann-Whitney U tests were used to compare the change in MFV (from 30° to 0°) between groups and between hemispheres within groups.ResultsFor stroke-affected MCAs in the incompletely recanalized group, MFVs differed at the various HOB angles (30°: median MFV=51.5 cm/s, interquartile range [IQR]=33.0 to 103.8; 15°: median MFV=55.5 cm/s, IQR=34.0 to 117.5; 0°: median MFV=85.0 cm/s, IQR=58.8 to 127.0); there were no significant differences for other MCAs. For stroke-affected MCAs in the incompletely recanalized group, MFVs increased with a change in the HOB angle from 30 degrees to 0 degrees by a median of 26.0 cm/s (IQR=21.3 to 35.3); there were no significant changes in the recanalized group (−3.5 cm/s, IQR=−12.3 to 0.8). The changes in MFV with a change in the HOB angle from 30 degrees to 0 degrees differed between hemispheres in the incompletely recanalized group but not in the recanalized group.LimitationsGeneralizability was limited by sample size.ConclusionsThe incompletely recanalized group showed changes in MFVs at various HOB angles, suggesting that cerebral blood flow in this group may be sensitive to orthostatic variation, whereas the recanalized group maintained stable blood flow velocities.

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