Vertebrobasilar insufficiency revealed by xenon-133 inhalation SPECT

Transient Vestibular Symptoms Preceding Posterior Circulation Stroke: A Prospective Multicenter Study

BACKGROUND AND PURPOSE

The recognition of clinical features of transient vestibular symptoms (TVSs) preceding posterior circulation stroke (PCOS) would be informative to discriminate dizziness/vertigo due to vertebrobasilar transient ischemic attack from the acute transient vestibular syndrome. We sought to determine the prevalence and characteristics of TVSs preceding PCOS.

METHODS

We performed a prospective multicenter observational study that had recruited 447 patients with PCOS from referral-based 4 university hospitals in Korea. We investigated the timing, pattern, frequency, duration, and accompanying neurological symptoms of TVSs during the 3 months preceding PCOS.

RESULTS

The prevalence of TVSs preceding PCOS was 12% (55/447) during the previous 3 months. The TVSs preceding PCOS occurred within 1 week (33%), between 1 week and 1 month (16%), or between 1 and 3 months (51%). The TVSs were mostly dizziness/vertigo with (36%) or without (60%) imbalance, while the remaining 4% had an isolated imbalance. The dizziness/vertigo was spinning in 38% and was aggravated during head position in 45%. The duration of TVSs was mostly a few seconds (55%) or minutes (38%). Approximately 72% of the patients with PCOS had TVSs 1 to 5 times, while 16% had >10 times. Accompanying neurological symptoms, including headache, tinnitus, limb weakness, sensory change, dysarthria, visual field defect, and diplopia, were reported in 11%.

CONCLUSIONS

Preceding TVSs can occur in 12% of PCOS during the previous 3 months. Isolated dizziness/vertigo of unknown cause needs to be considered as a vertebrobasilar transient ischemic attack symptom, especially in patients with vascular risk factors. The characteristics of isolated vestibular symptom in vertebrobasilar transient ischemic attacks is highly variable and atypical compared with other transient ischemic symptoms.

Have cranio-vertebral junction anomalies been overlooked as a cause of vertebro-basilar insufficiency?

STUDY DESIGN

A prospective controlled study using single photon emission computed tomography (SPECT) to assess cerebellar perfusion in a cohort of 19 patients with congenital cranio-vertebral junction (CVJ) anomalies, with or without vertebro-basilar insufficiency (VBI).

OBJECTIVE

To correlate symptoms of VBI with the presence of posterior circulation ischemia in patients with congenital CVJ anomalies, using technetium 99m ethylene cystine dimer SPECT.

SUMMARY OF BACKGROUND DATA

Patients with VBI are rarely investigated for CVJ anomalies, despite the fact that a significant number of patients with congenital CVJ anomalies has VBI. There are also no studies quantifying outcome of surgical interventions, such as like occipito-cervical fusion, in patients with VBI and CVJ anomalies.

METHODS

There were 19 consecutive patients with congenital CVJ anomalies who were scheduled for combined transoral odontoidectomy and occipito-cervical fusion were included in the study. Technetium 99m ethylene cystine dimer brain SPECT and clinical assessment of all patients was performed in the preoperative period and at 4 weeks after surgery. Before surgery, patients were divided into 2 groups depending on the clinical findings: (1) symptomatic group, consisting of 12 patients having features suggestive of VBI (drop attacks, episodic vertigo, visual disturbances and dysarthria); and (2) control group, consisting of 7 patients without symptoms of VBI.

RESULTS

SPECT showed decreased cerebellar perfusion in 75% (n = 9) of patients in the symptomatic group compared to 14% (n = 1) in the control group before surgery (Fisher exact 2-tailed test, P = 0.019). Following surgery, 8 patients (88.9%) in the symptomatic group and none in the control group had improvement in cerebellar perfusion. Two patients in the symptomatic group who had meningitis develop during the postoperative period had a decrease in cerebellar perfusion on follow-up SPECT. Clinically, all patients with improvement in cerebellar perfusion had improvement in the symptoms of VBI at 1 month of follow-up.

CONCLUSIONS

A significant number of patients with congenital CVJ anomalies who have symptoms of VBI develop have decreased cerebellar perfusion shown by SPECT. Rigid internal fixation of the CVJ may alleviate symptoms and improve posterior circulation in some of these patients.

Investigation of the vertebrobasilar arterial system in vertigo by vestibulocochlear test, SPECT and angiography

OBJECTIVE

Perfusion of the areas of cochleovestibular structures was investigated using Tc-99m HMPAO single photon emission computerized tomography (SPECT) in the young patients with vertigo presumed to have peripheral vestibular abnormalities and compared the results with cochleovestibular test results, and vertebrobasilar angiography findings.

METHODS AND PATIENTS

The study was performed on 20 patients with vertigo and 17 control subjects who had performed vertebral arteriography due to another disease. The patients with vertigo presumed to be on peripheral vestibular disorder were included in the study. Systemic and otorhinolaryngological examination were carried out. Audiovestibular function was evaluated in all patients and control subjects. Brain SPECT was performed with a one-head rotating gamma camera system from 64 projections into a 64x64 matrix, using low energy and high-resolution fan beam collimators with a sampling time of 30 s. The images taken from cerebellum, temporal, parietal and occipital lobes which are supplied by a vertebrobasilar system were compared visually with the other side and asymmetry in the perfusion was searched. After cochleovestibular tests and laboratory had been completed, vertebral arteriography was performed bilaterally in all patients. Results of digital subtraction angiography (DSA) and the vestibulocochlear test were compared with images of SPECT. Data analysis was done with Yates Chi(2) and percentages of sensitivity and specificity were calculated.

RESULTS

There was vestibular test and cochlear test abnormalities in eight and ten of the patients with vertigo, respectively. SPECT imaging showed hypoperfusion and decreased regional blood flow in 12 of the patients. There was statistically significant differences between the study and control groups in SPECT (P<0.05). Five patients showed abnormal findings in DSA examinations.

CONCLUSION

It is believed that SPECT may be helpful in the detection of vascular pathology in the patients with vertigo.

Isolated acute vertigo in the elderly; vestibular or vascular disease?

INTRODUCTION

Elderly patients with isolated acute vertigo are commonly encountered in clinical practice, but little is known about the underlying cause of the symptoms.

MATERIAL & METHODS

We prospectively studied 24 patients aged 50-75 years with the acute onset of isolated vertigo lasting > 48 h and no abnormality on neurological examination other than nystagmus. The study protocol included neuro-imaging (MRI 22 patients, CT 2 patients), Doppler sonography, and electro-oculography.

RESULTS

MRI/CT showed the presence of an infarction of the caudal cerebellum in six patients (25%), 3 of whom had a potential cardioembolic source and normal Doppler sonography findings, whereas 3 patients had ipsilateral vertebral artery occlusion and normal cardiac findings. MRI of the posterior fossa was normal in 18 patients. On electro-oculography, ataxic pursuit eye movements was a characteristic finding in patients with cerebellar infarction, whereas caloric test findings were not discriminative.

CONCLUSION

A caudal cerebellar infarction may easily be misdiagnosed clinically as a labyrinthine disorder, and was found to be the cause in one fourth of patients presenting with isolated acute vertigo.

Vertebrobasilar insufficiency: correlation of clinical and radiologic findings

Radiological and clinical findings of 20 cases with angiographically proven stenosis or occlusion of the vertebrobasilar system and with clinical signs and symptoms attributable to posterior circulation disorder were studied. A simplified classification of vertebrobasilar arterial disease was presented; type I refers to stenosis of the vertebrobasilar system or subclavian artery, type II refers to vertebrobasilar occlusion, and type III refers to vertebrobasilar branch disease. Type I lesions were further subdivided into types Ia and Ib; type Ia cases showed no infarction in the posterior territory, whereas type Ib cases showed one or more infarctions on computed tomography or magnetic resonance imaging. This angiographic classification is based on treatment options that can be adopted to specific types of lesion. In type I cases, lesions are usually amenable to surgical or angiographic intervention. In type II cases, short-term anticoagulation is the treatment of choice. In type III cases, treatment is primarily aimed at prevention of complication and further stroke.

Hemodynamic vertebrobasilar insufficiency caused by multiple arterial lesions: results of surgical treatment

From 1982 to 1990, 111 of 1013 patients undergoing cerebral artery reconstruction presented with signs of vertebrobasilar insufficiency associated with hemodynamically significant lesions of at least three cerebral arteries. There were 71 men and 40 women whose mean age was 70.3 +/- 8.4 years. Forty patients also had hemispheric symptoms, whereas three had ophthalmic symptoms as well. A total of 191 arteries were reconstructed in 139 procedures. During the first 30 postoperative days there were nine deaths (8.1%) attributable to four neurologic events--one myocardial infarction, two hemorrhages, and one acute kidney failure. There were 18 complications including seven neurologic events (four reversible and three irreversible), one myocardial infarction, and 10 reversible local complications. Mortality and morbidity were not affected if one (87 cases) or several (52 cases) cerebral arteries were reconstructed. Of 179 arteries for which follow-up arteriograms were obtained, two (1%) were found to be occluded. Mean follow-up was 41.2 +/- 27.7 months. Four patients were lost to follow-up, and 28 died: five of cerebrovascular causes in the 21 who died of cardiovascular causes and seven secondary to noncardiovascular events. Actuarial 5-year survival and patency rates were 63.3 +/- 10.9% and 97.3 +/- 2.8%, respectively. Functional results were evaluated in 98 patients. At the last follow-up visit 73 were asymptomatic, 13 were improved (80% good results), 5 were unchanged, and 7 were worse. Mortality and morbidity rates were superior to that for isolated carotid or vertebral artery surgery performed during the same period.(ABSTRACT TRUNCATED AT 250 WORDS)

Demonstration of human motor cortex activation using SPECT

Recent advances in single photon emission computed tomography (SPECT) have allowed improved image resolution with lower doses of labelled tracer. Capitalizing on these improvements, the authors have developed a new SPECT protocol for imaging neuronal activation. We outline this technique and describe how it can demonstrate increased human motor cortex activity in normal subjects performing a motor task. The ability to accurately demonstrate neuronal activation with SPECT using this method may have important scientific and clinical implications.

Assessing the effects of antihypertensive medication on cerebral blood flow: demonstration in internal carotid artery occlusion

Dynamic cerebral blood flow (CBF) studies using acetazolamide or hypercapnia as a vasodilatory challenge have attempted to evaluate intracranial hemodynamics. We report two patients with asymptomatic internal carotid artery occlusion in whom the vasodilatory stimulus was a single oral dose of antihypertensive medication (prazosin hydrochloride or enalapril maleate). In both patients, changes in regional CBF occurred that were larger than those seen in nine normal controls. One patient experienced an improvement in regional CBF with a reduction in probe pair asymmetry. In the other patient, who had bilateral carotid artery disease, a decrease in regional CBF in all 16 probes (mean decrease 12 percent) and an accentuation of the predose asymmetry were observed. Both patients remained asymptomatic throughout the study. Assessing these effects on cerebral circulation may help identify patients at risk for iatrogenic focal cerebral ischemia and provide information regarding the functional status of the cerebral vasculature.

The use of cerebral activation procedures with single photon emission tomography

Single photon emission tomography allows the imaging of dynamic brain functioning. The use of cerebral activating procedures within the scan protocol enables investigation of the mechanisms involved in specific brain functions in health and disease. Activation studies involve the comparison of at least two data sets describing brain activity generated in conditions that differ for the specific function in question. When designing an activation study, decisions regarding methodology include: the nature of the activation regime, the tracer-ligand utilized, the SPET instrument and the manner of subsequent data analysis. These issues are discussed in this review, both theoretically and with reference to published studies. Means of activating particular cerebral structures and functions are reviewed, as are the limitations of the techniques with respect to temporal and spatial resolution and the potentially confounding nature of preconceived ideas regarding the mechanisms of brain function.