INTRODUCTION :
Stroke is one of the leading causes of morbidity and ranks next only to coronary artery disease and malignancy as the leading cause of mortality worldwide. At least fifty percent of neurological disorders in a general hospital are due to stroke.
As remarked by a renowned neurologist, C. M. Fisher, neurology is learnt stroke by stroke.
Eighty percent of stroke is ischemic; twenty percent of ischemic events involve tissue supplied by posterior circulation. The paralysis of vertebrobasilar stroke can devastating and some forms have high rates of death. Many cases of vertebrobasilar diseases remain undiagnosed or are incorrectly diagnosed. Formerly clinicians used the catchall term vertebrobasilar insufficiency to indicate a hemodynamic cause of all cases of posterior circulation ischemia.
During the past fifteen years information provided by detailed clinical studies and brain imaging has revolutionized our understanding of clinical aspects, mechanism, treatment and prognosis of posterior circulation ischemic stroke.
The etiology of posterior circulation ischemia has been thought to be primarily due to local arterial atherosclerosis (large artery disease) and penetrating artery disease (lacunes) However there is increasing evidence that cardiogenic embolization is more common than previously suspected and is responsible for 20 – 50% of posterior circulation strokes.
The posterior circulation, unlike the intracranial portions of the anterior circulation, is prone to atherosclerosis much as other systemic arteries. In the case of one vertebral artery being occluded, collateral flow comes from the opposite vertebral artery, from muscular cervical artery branches, and from posterior communicating artery.
Now with better understanding of risk factors involved in stroke the emphasis should be prevention rather than management.
AIMS OF THE STUDY :
1. To evaluate the etiology in posterior circulation stroke.
2. To study the commonest mode of clinical presentation in posterior circulation ischemic stroke.
3. To evaluate the commonest anatomical area involved and the size of the infract with the help of imaging modalities (CT and MRI).
4. To assess the outcome.
MATERIALS AND METHODS :
This study was carried out in patients who presented with posterior circulation ischemic stroke to the medicine and neurology department of PSG Institute of Medical Sciences and Research, Coimbatore.
The study was conducted during the period of January 2005 to march 2006.
All patients admitted with clinical features suggestive of posterior circulation stroke were taken. All were subjected to CT scan brain. Patients with evidence of posterior circulation stroke clinically and imaging wise were taken up for the study.
Inclusion Criteria:
All patients with clinical features suggestive of posterior circulation stroke Imaging showing infarcts within the posterior circulation territory.
Exclusion Criteria:
CT evidence of showing haemorrage
Patients having evidence of infarcts in other areas ie. , territory of anterior circulation, border zone infarcts.
Patients on ventilator, global aphasia, in coma were excluded from studies.
All the patients were evaluated in detail. A detail history was recorded with special emphasis on risk factor, mode of presentation, time interval between onset and arrival to hospital.
Major risk factor included in this study are hypertension, diabetes mellitus, dyslipidemia, age sex, coronary artery disease, smoking, alcohol intake, and transient ischemic attack
Special emphasis was given for clinical evaluation of cardiovascular system with regard to rhythm disturbances cardiac failure, and valvular heart disease.
Detailed clinical neurological examination was done and the patients were grouped into posterior circulation stroke Blood haemogram, peripheral smear, haematocrit, blood sugar lipid profile, and renal function tests were done. Echocardiogram was done. to rule out intracavitary clots and vegetation. Imaging studies including CT, MRI and Doppler Studies were done to localize the anatomical area involved and to know the size of the area involved.
Outcome was assesed according to the modified rankin scale at 30 days.
DISCUSSION :
Cerebrovascular disease was more common in men in the age group of >60 years. In ‘tufts posterior registry’ 52% were male and 48% were females. Smajlonc D33 studied ischemic insult in both anterior and posterior circulations and he found 18. 2% had posterior circulation stroke and he also found females and males were equally affected in posterior circulation stroke.
In this study 63. 75% were males. Though the above mentioned study showed sexual equality our study showed a male preponderance.
Mean age of pts in our study was 60 years which was similar to other studies.
The risk factors in stroke are classified as modifiable and non modifiable. Male sex and older age are non-modifiable risk factors.
Hypertension is the most common risk factor associated with stroke.
In our study 52. 5% were hypertensives this was similar to the stoke study of Nizam’s Institute Hyderabad.
Diabetes mellitus, hypercholesterimia, smoking, obesity, ischemic heart disease, atrial fibrillation, heamatocrit elevation are other modifiable
risk factors.
CONCLUSION :
In my study I found that
• Males were affected more than females.
• Age group commonly involved was above sixty yrs.
• Hypertension, diabetes and smoking contributed the major risk factors followed by cardio embolic source.
• Giddiness was commenest symptom at the onset.
• Most of the patients had clinical signs of cerebellum and brainstem lesions.
• The territory commonly involved was mid-brain, cerebellum, thalamus, occipital and temporal lobes.
• MRI was found to be more sensitive than CT in identifying brain stem lesions.
• Outcome in posterior circulation stroke was found to be better than anterior circulation stroke
