Evaluation of cerebrovascular reactivity by ultrasonography in type 2 diabetic patients with hypertension

BACKGROUND： Cerebrovascular reactivity （CVR） reflects cerebrovascular reserve capacity, and cerebrovascular reactivity damage prognosticates a very high risk of stroke. OBJECTIVE： To evaluate CVR by detecting the increase rate of blood flow volume of middle cerebral artery （MCA） before and after breathholding in diabetic patients with hypertension, and observe the effects of hypertension on cerebrovascular reserve capacity of diabetic patients. DESIGN： Controlled observation. SETTINGS： Department of Function, Affiliated Hospital of Hebei University; Department of Special Diagnosis, the 202 Hospital of Chinese PLA. PARTICIPANTS： Inpatients or outpatients with type 2 diabetes mellitus （DM） or primary hypertension admitted to Departments of Gastroenterology and Cardiology, Affiliated Hospital of Hebei University and the 202 Hospital of Chinese PLA from April to December 2004 were involved in this experiment. Inclusive criteria： type 2 DM met the criteria of the report on diabetes diagnosis announced in 1999 by WHO expert committee, totally 88 patients were involved. Primary hypertension met the diagnosis criteria announced in 1999 by WHO/ISH, totally 42 patients were involved. Another group of 43 concurrent subjects who received physical examination served as controls. According to the disease condition, the involved patients were assigned into 3 groups： DM group （only diabetic patients）, hypertension group （only hypertension patients） and DM complicated with hypertension group （diabetic patients with hypertension）. Informed consent for the examination was obtained from all the involved subjects. METHODS： Before MCA of subjects was detected, bilateral carotid artery was routinely detected by high-frequency ultrasonography. Subjects were rejected when stenosis rate of unilateral internal carotid artery or common carotid artery ≥ 70%. Vessels were expanded with transcranial color Duplex Doppler by breath holding test for detecting vascular reactivity. Hypercapnia was created by BHT. The mean velocity and diameter of blood flow were detected under the quiescent condition and 25 s after breath holding with transcranial color-coded duplex sonography. The volume of blood flow of MCA was calculated according to the following formula： Volume of blood flow of MCA （mL/ min） = （the diameter of blood flow /2） 2×π× mean blood flow velocity×60. The increase rates of mean blood flow velocity and blood flow volume of patients with hypercapnia were calculated as compared with under the quiescent condition to evaluate cerebrovascular reactivity. MAIN OUTCOME MEASURES： Mean blood flow velocity, blood flow diameter and MCA blood flow volume as well as the increase rates of them. RESULTS： Among the 173 participates, 103 patients and 39 healthy controls were involved in the final analysis, and the other 31 dropped out due to not accomplishing the examination. ①Comparison of blood flow parameter of MCA under the quiescent condition： The mean blood flow velocity of DM complicated by hypertension group was significantly higher than that of DM group （P 〈 0.05） and control group （P 〈 0.05）; The blood flow diameter of DM complicated by hypertension group was significantly smaller than that of control group （P 〈 0.01）. Under the quiescent condition, significant difference was not found in the intergroup comparison of blood flow volume of MCA. ② Comparison of increase rate of blood flow parameter： In the DM group, hypertension group, DM complicated by hypertension group and control group, the increase rate of mean blood flow velocity of was （29.34±4.50）%,（29.35±4.35）%,（26.68±4.99）% and （30.99±3.54）%, respectively, the increase rate of blood flow volume of MCA was （35.32±5.08）%, （35.36±6.16）%,（31.78±7.11）% and（37.26±4.17）%, respectively, and the increase rate of blood flow diameter was （2.29±1.09）%,（2.27±0.95）%,（1.97±1.05）% and（2.36±0.46）%, respectively. The increase rate of mean blood flow velocity and that of blood flow volume of MCA in the DM complicated byhypertension group were significantly lower than those in the other 3 groups （P 〈 0.05）. CONCLUSION： CVR is markedly lowered and cerebrovascular reserve capacity is damaged in diabetic patients with hypertension.

Bow hunter’s syndrome successfully treated with a posterior surgical decompression approach:A case report and review of literature

BACKGROUND Bow hunter’s syndrome(BHS)is a rare but surgically treatable cause of vertebrobasilar insufficiency due to dynamic rotational occlusion of the vertebral artery.Typically,patients present with posterior circulation transient ischaemic symptoms such as presyncope,syncope,vertigo,diplopia,and horizontal nystagmus,but irreversible deficits,including medullary and cerebellar infarctions,have also been described.CASE SUMMARY A 70-year-old patient presented an acute onset of vertigo and gait instability triggered by right head rotation.His medical history included previous episodes of unilateral left neck and occipital pain followed by light-headedness,sweating,and blurred vision when turning his head,and these episodes were associated with severe degenerative changes in the atlanto-dens and left atlanto-axial facet joints and right rotation of the C2 cervical vertebrae.Brain magnetic resonance imaging revealed the presence of acute bilateral cerebellar ischaemic lesions,while static vascular imaging did not reveal any vertebral artery abnormalities.Dynamic ultrasonography and angiography were performed and confirmed the presence of a dynamic occlusion of the vertebral artery V3-V4 segment when the head was rotated to the right secondary to left C1-C2 bone spur compression.Surgical decompression led to complete resolution of paroxysmal symptoms without neurological sequelae.CONCLUSION BHS should be considered in cases of repeated posterior circulation transient ischaemic attack or ischaemic stroke,particularly when associated with high cervical spine abnormalities.