Nuclear hemodynamic vertebrobasilar insufficiency. A new approach with the xenon Xe 133 method

Vertebrobasilar insufficiency is a well-known syndrome, but no corresponding hemodynamic deficit has yet been established. We propose to define nuclear hemodynamic vertebrobasilar insufficiency on the basis of an oligemia lower than 35 mL/100 g per minute in the brain stem-cerebellar region with use of the xenon Xe 133 inhalation method. Fifteen patients fulfilling this criterion underwent four-vessel angiography, computed tomography, and a standardized neurologic examination. An acetazolamide test showed poor reactivity in more than half of the patients, sometimes specifically in the vertebrobasilar area. With use of single-photon emission computed tomography and intravenous technetium Tc 99m-labeled hexamethylpropyleneamineoxime in two cases, the considerable decrease of regional cerebral blood flow in the brain stem-cerebellar region was confirmed. An excellent correlation was observed between the existence of nuclear hemodynamic vertebrobasilar insufficiency and angiographically proved arterial occlusions. The dominant nuclear oligemic zone was regularly on the side of the anatomic arterial chief lesion. Clinical manifestations included rare transient ischemic attacks (in one of 15 patients), intermittent basilar symptoms (in 15 of 15 patients), and a subacute vertebrobasilar "threatening" syndrome. Thus, imaging of a nuclear hemodynamic vertebrobasilar deficit provides an objective basis to the diagnosis of vertebrobasilar insufficiency and useful objective data for revascularization surgery.     

Assessment of cerebral blood flow and metabolism in vertebrobasilar insufficiency with 133Xenon and 15O inhalation methods

Abstract

Assessment of hemodynamic parameters in patients who had transient basilar symptoms suggesting vertebrobasilar insufficiency requires a systematic and .accurate detection of brainstem or cerebellar infarcts. Our aim was to detect with 133Xenon and ¹⁵0₂ inhalation methods, a low flow state underlying vertebrobasilar insufficiency in a patient who had no impairment of cerebrovascular control related to infarction of brainstem or cerebellum. A woman with intermittent vertebrobasilar symptoms had an angiogram, magnetic resonance imaging and evaluation of hemodynamic parameters with vertebrobasilar circulation with 133Xenon inhalation and ¹⁵0 inhalation methods MRI failed to show any border-zone or territorial infarcts or degenerative disease..Angiographic study showed significant arterial lesion involving vertebrobasilar vessels. A decrease ofblood flow within vertebrobasilar circulation was observed according to 133Xen"on and ¹⁵0 inhalation methods. These preliminary results support the view that significant arterial changes within the vertebrobasilar system might account for a low flow state. ¹⁵ 0 ₂ inhalation method might be in agreement with a previous study performed in vertebrobasilar insufficiency with 133Xenon inhalation method. [Neural Res 1997; 19: 165–168]     

Use of cerebrovascular reactivity in patients with symptomatic major cerebral artery occlusion to predict 5-year outcome: comparison of xenon-133 and iodine-123-IMP single-photon emission computed tomography.

The aim of this prospective study was to investigate whether decreased cerebrovascular reactivity to acetazolamide, as determined by single-photon emission computed tomography (SPECT), is an independent predictor of the 5-year risk of subsequent stroke in patients with symptomatic major cerebral artery occlusion. Cerebrovascular reactivity to acetazolamide in the middle cerebral artery (MCA) territory ipsilateral to the occluded artery was determined on the basis of two different methodologies: cerebral blood flow (CBF) percent change obtained quantitatively from xenon-133 (133Xe) SPECT, and asymmetry index (AI) percent change obtained qualitatively from N-isopropyl-p-[123I]-iodoamphetamine (IMP) SPECT. Seventy patients with unilateral internal carotid artery or MCA occlusion were divided into two groups within each SPECT methodology (normal or decreased CBF percent change and AI percent change) and followed up for 5 years. Cumulative recurrence-free survival rates for patients with decreased CBF percent change were significantly lower than for those with normal CBF percent change (P = 0.0205). There was no significant difference in cumulative recurrence-free survival rates between patients with decreased AI percent change and those with normal AI percent change. Only decreased CBF percent change was a significant independent predictor of stroke recurrence (P = 0.0051). The present study demonstrated that decreased cerebrovascular reactivity to acetazolamide determined quantitatively by 133Xe SPECT is an independent predictor of the 5-year risk of subsequent stroke in patients with symptomatic major cerebral artery occlusion, and that the qualitative method using 123I-IMP SPECT is a poor predictor of the risk of subsequent stroke in this type of patient.     

Comparative study of regional cerebral blood flow values measured by Xe CT and Xe SPECT

The regional cerebral blood flow (rBCF) values measured by stable xenon-enhanced computed tomography (Xe XT) and by radioactive xenon-133 single photon emission computed tomography (Xe SPECT) were compared in 16 patients with cerebral infarct. On the non-lesion side Xe SPECT recorded 10.7% higher rCBF values than Xe CT in the anterior cerebral artery territory while Xe CT recorded 9.6% higher values than Xe SPECT in the middle cerebral artery territory. These differences were not statistically significant. Although the rCBF values were almost the same no correlation was found between the two methods in the posterior cerebral artery territory and the basal ganglia. Only hemispheric CBF on the non-lesion side showed the same value and a good correlation between the Xe CT and the Xe SPECT. There was a good correlation in the hemispheric CBF values on the lesion side, too. The difference of rCBF between the non-lesion side and the lesion side was expressed smaller in the Xe SPECT than in the Xe CT. This is in agreement with the previous reports that Xe SPECT overestimates the flow in the low flow areas. The higher rCBF values in the anterior cerebral artery territory measured by the Xe SPECT was ascribed to the artifact from the radioactivities in the inhalation mask and the air passages as reported previously. In conclusion, there is no good correlation between the rCBF values measured by the Xe CT and by the Xe SPECT. Only hemispheric CBF shows a good correlation between the two methods.     

Regional cerebral blood flow during an attack of vertebrobasilar insufficiency

Using technetium-99m-labeled hexamethylpropyleneamineoxime [( 99mTc]HM-PAO) and single-photon emission computed tomography, we measured changes in regional cerebral blood flow in a 58-year-old man during an attack of vertebrobasilar insufficiency. Angiography demonstrated compression of the left vertebral artery by the osteophytes of cervical spondylosis when the patient turned his head to the left. Measured in the orthostatic position while turning his head to the left during a typical attack of vertebrobasilar insufficiency, regional cerebral blood flow was significantly reduced in the left cerebellum and the right occipital region. Our study illustrates the capability of [99mTc]HM-PAO single-photon emission computed tomography to measure transient reductions in regional cerebral blood flow and to relate these changes to the pathophysiology of vertebrobasilar insufficiency.     

Surgical correction and SPECT imaging of vertebrobasilar insufficiency due to unilateral vertebral artery stenosis.

BACKGROUND AND PURPOSE: Incapacitating vertebrobasilar insufficiency is generally associated with bilateral vertebral artery disease, whereas unilateral vertebral artery stenosis usually is clinically silent. Regional brain perfusion has not been part of the routine evaluation of patients with vertebrobasilar insufficiency. This report describes two patients who had isolated unilateral vertebral artery stenosis operatively corrected to eliminate their incapacitating vertebrobasilar insufficiency. Hindbrain hypoperfusion was identified preoperatively and evaluated postoperatively, then correlated with patient presentation and response to revascularization. CASE DESCRIPTION: Two patients with incapacitating vertebrobasilar insufficiency presented with isolated unilateral vertebral artery stenosis with patent, nonstenotic internal carotid arteries. Hindbrain hypoperfusion was demonstrated by iodine-123-iodoamphetamine single-photon emission computed tomography preoperatively and demonstrated significant improvement following vertebral-carotid reimplantation. The patients' symptoms resolved following revascularization. CONCLUSIONS: Although unusual, unilateral vertebral artery stenosis can cause incapacitating vertebrobasilar insufficiency. These cases demonstrate the value of imaging with single-photon emission computed tomography to evaluate regional brain hypoperfusion and to evaluate objectively the results of therapy.     

西比灵治疗椎基底动脉供血不足的TCD和rCBF研究

目的：研究椎基底动脉供血不足（ＶＢＩ）患者服用西比灵治疗后脑血流动力学和脑血流量变化。方法：２２例ＶＢＩ患者西比灵治疗前及治疗４周后分别行经颅多普勒（ＴＣＤ）和１３３氙吸入法局部脑血流量（ｒＣＢＦ）检测。结果：西比灵治疗后椎基底动脉系统血流速增快,但与治疗前相比无显著差异（Ｐ＞０．０５）;治疗后全脑血流量增高,其中脑干、小脑区脑血流量明显高于治疗前（Ｐ＜０．０５）。结论;西比灵能改善ＶＢＩ患者脑循环,治疗ＶＢＩ安全有效。     

Cerebral crossed diaschisis caused by cerebellar lesion: role of the cerebellum in mental functions

In 3 patients with a stroke limited to the posterior fossa, regional cerebral blood Flows were measured by the 133 Xe inhalation method (the first two cases) or by the SPECT with HMPAO method (the third case). The first patient had a median and paramedian hematoma of the left cerebellar hemisphere and the left dorsolateral portion of the pons. Remote cerebral hypoperfusion, measured 3 months later, was observed in both frontal premotor regions (but more marked in the right hemisphere) and in a circumscribed area of the right temporal region. The second patient had a right-sided ischaemic lesion of the anterior cerebellar lobe and the mesencephalic tectum. Contralateral parietal and rolandic hypoperfusion, measured 7 weeks after the stroke, was observed. The third patient had on old infarct of the right cerebellar hemisphere. The SPECT, measured 17 years later, showed a left fronto-parieto-temporal hypoperfusion and the absence of perfusion in the right cerebellar hemisphere. Preliminary data of neuropsychological assessment in our patients disclosed impairment in visuo-spatial and constructive organization, memory and learning compatible with the published findings in some patients and animals with predominantly cerebellar damage. These interesting findings should be confirmed in a large number of patients with age, sex, and sociocultural matched controls. In the absence of supratentorial insult, and during the hemodynamical stable phase, crossed cerebello-cerebral diaschisis is suggested in our 3 patients. Although it is too early to draw definite conclusions, our findings may: (1) confirm the functional interconnections between the cerebellum and the cerebrum in man and (2) provide functional basis for the behavioral function impairment reported in patients with cerebellar insult. Further rCBF, metabolism, and pathologic studies on this subject are required to elucidate this issue.     

A case of severe stenosis of bilateral distal vertebral artery successfully treated with anastomosis operation]

A 65-year-old male complained of loss of consciousness for several minutes, transient diplopia and dizziness. He had no neurological deficits nor abnormalities in MR imaging. However, flow velocity of bilateral vertebral artery on ultrasonography indicated severe stenosis of bilateral distal vertebral artery. Brain angiography revealed severe stenosis of bilateral distal vertebral artery as well as occlusion of right middle cerebral artery (MCA). Single photon emission CT (SPECT: ECD-RVR method with acetazolamide loading) showed decreased cerebral blood flow and poor perfusion reserve in bilateral cerebellar hemisphere and right MCA territory. Superficial temporal artery-superior cerebellar artery (STA-SCA) anastomosis was performed. The patient turned out to have no episodes of unconsciousness attack, transient diplopia and dizziness after operation. Cerebral blood flow (CBF) in the posterior circulation was also improved. Evaluating quantitative CBF measurement by means of ECD-RVR method was useful for evaluating CBF. In cases who have severe stenosis of bilateral distal vertebral artery with complaints of vertebrobasilar insufficiency, STA-SCA anastomosis may be one of the most effective treatments.     

A serial study of regional cerebral blood flow before and after hemispherectomy in a child

Hemimegalencephaly (HME) is a severe unilateral brain malformation the prognosis of which may be improved by hemispherectomy. HME also provides a unique opportunity to compare normal and pathological hemispheric function in the same patient. We performed a serial functional cerebral imaging study in a child suffering from a neuropathologically confirmed left HME. He was hemispherectomized at 11 months because of intractable epilepsy; this led to cessation of seizures and dramatic psychomotor improvement. Regional cerebral blood flow (rCBF) was studied at 1, 7, 10, 12 and 25 months with single photon computed tomography (SPECT) using 133-Xenon and with simultaneous EEG recording. At one month of age SPECT was performed ictally. During left EEG discharges, rCBF was 40% higher on the left hemisphere than on the right, even in occipital and frontal regions, usually immature at this age. A crossed cerebellar hyperperfusion was also found. At 7 and 10 months, SPECT was performed interictally; rCBF was 45% lower in the left hemisphere than in the right. During follow-up, global and regional CBF values showed normal levels and normal maturation in the right hemisphere except for a mild and transient decrease observed one month after hemispherectomy. SPECT provides an additional procedure for studying hemispheric function in vivo. Serial SPECT imaging may be useful for the preoperative and postoperative evaluation in unilateral cerebral malformation.     

Regional cerebral blood flow measured by 133Xe inhalation in tracheostomized and laryngectomized men and women.

The question of contamination of cerebral clearance curves utilized for measuring regional cerebral blood flow by radioactivity derived from the nasopharyngeal air passages following inhalation of 133Xe was tested in patients with chronic tracheostomy. The peak counts for head curves were 5--9% higher when 133Xe was inhaled via a face mask than when inhaled via the tracheal stoma. Calculated flow values using standard recommended start-fit-times were not significantly different between these two different methods. Present results indicate that neither overestimation of fast flow values due to contamination from rapid 133Xe washout recorded from the air passages nor the underestimation of slow flow due to contamination from 133Xe trapped in the air sinuses produced significant measurement errors. However, if earlier start-fit-times were used, flow values were artificially high, particularly for brain stem/cerebellar probes because of an initial rapid decline in the head desaturation curves due to an arterial peak believed to be derived from the basilar artery.     

Transient global amnesia followed by vertebrobasilar ischemia in a case of dolichoectatic basilar artery

A 59-year-old hypertensive patient presented with transient global amnesia without neurological signs or symptoms. During the following 3 years, he experienced several attacks of vertebrobasilar insufficiency and a cerebellar infarction. CT scan and MRI found a partially thrombosed dolichoectatic basilar artery but no significant lesion within the limbic system. These data suggest transient global amnesia was due to a transient ischemia in the basilar artery distribution.     

Crossed cerebellar diaschisis in ischemic stroke: a study of regional cerebral blood flow by 133Xe inhalation and single photon emission computerized tomography

Seventy measurements of CBF were performed in 12 stroke patients by 133Xe inhalation and a rapidly rotating single photon emission computerized tomograph. CBF was measured every other day during the acute phase and at 2- and 6-month follow-up visits. A persistent contralateral cerebellar blood flow depression was evident in five patients with severe hemispheric low flow areas, which correlated with large, hypodense lesions on the computerized tomographic scan. In a sixth patient with a small, deep infarct, a transient crossed cerebellar low flow was observed, while the clinical symptoms persisted. It is concluded from this serial study that crossed cerebellar diaschisis is a common finding in completed stroke. It is probably caused by disconnection of the corticopontine pathways, a disconnection that tends to persist. The phenomenon is in fact less variable than the stroke-related CBF changes in the infarcted hemisphere, in which a period of relative hyperemia is frequently seen.     

Correlation between diffuse alpha wave pattern of EEG and hyperfrontal pattern of regional cerebral blood flow

Regional cerebral blood flow (rCBF) was measured in three groups; (1) 20 healthy subjects, (2) 14 patients with diffuse alpha wave pattern of EEG, (3) 14 patients without diffuse alpha wave pattern matching with ages of group 2. In the group 2, one patient with transient ischemic attack, 7 with reversible ischemic neurological deficit, 3 with vertebro-basilar insufficiency, 2 with minor stroke and one with posttraumatic sequelae were selected for rCBF measurements. In the group 3, 3 patients with transient ischemic attack, 7 with reversible ischemic neurological deficit, 2 with vertebro-basilar insufficiency and 2 with minor stroke were selected for rCBF measurements. Electroencephalographic analyses were performed by using a BERG-Fourier Analyzer, simultaneously with rCBF measurements. All patients in the group 2 had diffuse alpha wave (generalized continuous simple rhythmic alpha wave--Hori et al) pattern of EEG. Regional cerebral blood flow measurement was performed with intracarotid injection method of 133Xe (10 mCi) by using the scintillation camera and on-line computer system. 133Xe clearance curve from the whole hemisphere were computed by height over area method. Regional value were obtained from brain areas of 6 mm X 6 mm. Mean hemispheric values were 59.2 +/- 7.9 ml/100 g/min in the group 1, 47.8 +/- 4.9 ml/100 g/min in the group 2 and 49.0 +/- 3.7 ml/100 g/min in the group 3. Although difference between group 2 and 3 was not significant, difference between group 1 and 2 was significant (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)     

Blood flow imaging of a posterior circulation stroke. Use of technetium Tc 99m hexamethylpropyleneamine oxime and single photon emission computed tomography

Regional cerebellar perfusion was imaged using technetium Tc 99m hexamethylpropylene amine oxime and single photon emission computed tomography (HM-PAO-SPECT) in a patient with chronic left lateral medullary syndrome with contralateral weakness due to traumatically induced thrombosis of the left vertebral artery. Despite continued neurologic deficits, x-ray transmission computed tomography was normal. However, HM-PAO-SPECT demonstrated that blood flow to the left cerebellar hemisphere was significantly impaired. This abnormality was still apparent after correction for atrophy as estimated by magnetic resonance imaging. Technetium Tc 99m hexamethyl-propyleneamine oxime and single photon emission computed tomography effectively imaged regional blood flow in the vertebrobasilar circulation and appears to more clearly reflect the nature and extent of the neurologic deficit than either x-ray transmission computed tomography or magnetic resonance scanning.     

Perfusion mapping with Tc-HMPAO in cerebral haematomas.

The cerebral distribution of HMPAO was mapped tomographically by SPECT in 20 patients with an intra cerebral haematoma. The images were assessed visually and by an analysis of an asymmetry index (AI) for various cerebral areas. Visual inspection identified the lesion in each of the 20 cases. Reduced tracer activity and abnormal AI were consistent findings. Remote effects (diaschisis) were also observed in the adjacent (19 cases) and frontal (14 cases) cortex, and in the controlateral cerebellum (16 cases). Sequential studies at 60, 150 and 300 minutes in 10 patients showed remarkably stable patterns. HMPAO maps were compared with cerebral blood flow (CBF) measured with 133 Xenon (133Xe) in eight cases. The two methods showed similar results in the region of a lesion, but remote effects were more obvious with the 133Xe in two patients.     

Comparison of external lung monitoring with end-tidal air detection using the 133xenon inhalation method

When the 133Xe inhalation method is employed for measuring regional cerebral blood flow, the arterial 133Xe concentration is usually approximated by the end-tidal air concentration. However, this approximation may be invalid in the presence of certain lung pathologies or when the breathing pattern is irregular. Jaggi and Obrist, using an intravenous injection of 133Xe, suggested that the counts detected by an external lung probe could provide an alternative estimate for arterial blood concentration once the noise produced by 133Xe in superficial tissues is removed from the signal. A mathematical model, based on hypotheses similar to theirs is presented here together with a new computational procedure for removing the noise. Results from normal rest studies on ten healthy young males indicate that the approximations for arterial blood concentration obtained from end-tidal air and from corrected lung counts are not equivalent when 133Xe is administered by inhalation. The concentration-time curves have different shapes, and these differences are reflected in blood flow values computed by head channel. However, there is no effect on comparisons between homologous regions of the left and right hemispheres.     

Bilateral vertebral artery occlusion associated with atlantoaxial dislocation due to os odontoideum]

A 17-year-old boy was hospitalized with transient consciousness disturbance on extension of the neck. At seven years of age, the patient developed delayed-onset posterior circulation stroke after the door struck him a mild blow on his forehead. A computed tomography scan revealed right cerebellar infarction with unknown etiology. He had been followed up without stroke recurrence and CT change until this hospitalization. Cerebral angiography disclosed bilateral vertebral artery occlusion at the C-2 level with the well-developed muscular collateral artery bypassing the occluded left vertebral artery. A cervical X-ray showed a posterior atlanto-axial subluxation with os odontoideum. Compression of the vertebral arteries due to mild trauma aggravating an atlanto-axial subluxation may have caused the bilateral vertebral artery thrombosis resulting in occlusion, and disturbance of the muscular collateral circulation on extension of the neck may have led to the recurrence of vertebrobasilar insufficiency. This is the first report of the angiographically confirmed bilateral vertebral artery occlusion with an established etiology in childhood.     

Clinical patterns of Arnold-Chiari malformations]

The purpose of the study was clinical analysis of the patients with Arnold-Chiari malformation and the definition of the groups according to the clinical presentation. The authors present the series of 210 patients treated between 1980 and 1997 in the Department of Neurosurgery. These patients were classified into 4 groups: syringomyelia, cerebellar syndrome, cerebello-spinal syndrome and hydrocephalus. Syringomyelia was the commonest clinical presentation in the series. Less often cerebellar and cerebello-spinal syndromes were observed. Non-communicating hydrocephalus was rare. The symptomatology of the Arnold-Chiari malformation appears extremely variable, but most often is related to the associated cavitation of the spinal cord. The signs and symptoms in patients presenting cerebellar syndrome may lead to misdiagnosis of insufficiency of the vertebrobasilar circulation. Diffuse involvement of the motor and sensory system with cerebello-spinal syndrome may cause the patient to be diagnosed incorrectly as having sclerosis multiplex. The MR is the method of choice in the diagnosis of Arnold-Chiari malformation.     

Pitfall of Electron Beam Computed Tomography Angiography in Diagnosis of Subclavian Steal Syndrome

A patient presented with vertebrobasilar insufficiency during exertion. Vertebral duplex and transcranial Doppler ultrasonography showed reversal of flow in both intracranial and extracranial vertebral and basilar arteries, suggesting bilateral subclavian and vertebrobasilar steal. Electron beam computed tomography angiography (CTA) showed no evidence of subclavian artery stenosis including normal vertebral artery origin on both sides. However, digital subtraction angiography revealed complete occlusion of both subclavian arteries with retrograde flow from both vertebral and basilar arteries to reconstitute both subclavian arteries. This false-negative finding on CTA in detection of subclavian steal syndrome (SSS) is due to inappropriate contrast administration technique and postprocessing method, inability to differentiate flow direction, and lack of hemodynamic time sequences. This study demonstrates a pitfall of CTA in diagnosis of SSS compared to more reliable hemodynamic information obtained by duplex and transcranial Doppler ultrasonography, and digital subtraction angiography.