An observational cross-sectional study of clinical profile of posterior circulation ischemic stroke in a tertiary care teaching hospital in Eastern India

Introduction

Brain stroke remains one of the major causes of mortality and long term morbidity in the society. It has a high impact on the personal, psychological, social and economic status of the patient as well as the caregivers. After cancer and ischemic heart disease, cerebral stroke is the third most common cause of death in the developed world.^[1] This is very common in developing countries like India.^[2]

Cerebral stroke can be either hemorrhagic or ischemic. The World Health Organization (WHO) defines stroke as “rapidly developing clinical signs of focal (or global) disturbance of cerebral function, with symptoms lasting 24 hours or longer or leading to death, with no apparent cause other than vascular origin”.^[3]

Posterior circulation strokes account for 10 to 15% of all cerebral strokes. ^[4] Posterior circulation territory includes anatomical sites like occipital, medial temporal lobe, thalamus, brainstem, cerebellum. Posterior circulation blood flow consists of two vertebral arteries, one basilar artery and two posterior cerebral arteries through many short penetrating and circumferential branches. ^[5] Posterior circulation stroke differs from anterior circulation stroke with reference to risk factors, clinical symptomatology and prognosis. Clinical features of posterior circulation stroke encompasses fluctuating sensorium, cranial neuropathy, visual disturbances, cerebellar ataxia, etc. They have been described as various clinico-anatomical syndromes like Claude’s, Weber’s, Balint’s, lateral medullary, medial medullary, locked in state and top of basilar syndrome. ^[6]

There are a few hospital based studies to delineate detailed risk factors, clinical profile, vascular territory involvement, prognosis for posterior circulation ischemic strokes in India. We report 282 patients, by far the largest no of cases with posterior circulation ischemic stroke from India.

Material and Methods

An observational cross-sectional hospital based study was conducted in the Department of Medicine and Neurology at Hi-Tech Medical College and Hospital, Bhubaneswar, Odisha from January 2020 to June 2021 (Eighteen months). An informed consent was taken from all the patients/ eligible relatives. Ethical Clearance was obtained from the Institutional Ethical Committee.

During this period, all patients with posterior circulation ischemic cerebral stroke, admitted as inpatient care were included. Clinical history was documented and examined clinically. All the patients were investigated for Complete blood count, urine analysis, fasting blood sugar, renal function test, liver function test, serum electrolytes, lipid profile, chest radiography, ECG, 2-D ECHO and Carotid Doppler study. MRI Brain scan was done for all patients and analyzed with the help of neuroradiologist. Diagnosis was be made on the basis of medical history, physical examination and neuro imaging. Transient ischemic attack was defined as the abrupt onset of focal neurological deficit lasting for less than 24 hours.

Informed consent was obtained from the patients or their close relatives. Patients/ Relatives were interviewed within 48 hours of admission and at the time of discharge to collect relevant data.

The data was collected in a specially pre-designed structured proforma. The demographic data, risk factors, clinical findings, treatment and any complications during hospital stay were noted. Stroke onset symptoms, National Institutes of Health Stroke Scale Score (NIHSS) ^[7] were noted.

Results

A total of 1803 patients were admitted to the medicine/neurology department with ischemic cerebral stroke during the study period. Out of which, 293 (16.2%) patients, presented as posterior circulation ischemic stroke. Eleven patients were excluded due to inadequate history or neuroimaging.

In the study cohort of 282 patients, 196 (69.5%) were males and 86 (30.5%) were females. The male to female ratio of stroke was 2.27:1. The age ranged from 22 to 87 years with mean age of 54.4 (± 13.6) years. Stroke was more common in the middle aged and elderly group as 140 patients (49.6%) were from 40 to 59 age group. [[Table 1]] In our study group 56(19.8%) patients were young stroke (< 45 years)

Patients presented to hospital with mean duration of 15.7 (±12.26) hours after stroke onset. Ten patients presented within window period (< 4.5 hour) for intravenous thrombolysis.

The most common risk factors of stroke were hypertension [176 (62.4%)] and diabetes [(122(43.2%)]. [[Table 2]]. Some rare risk factors like systemic vasculitis (SLE, APLA syndrome), Congenital Prothrmbotic state (Protein C deficiency, Factor V Leiden mutation), oral contraceptive uses, etc were also noted in this study.

As patient had multiple stroke risk factors at the time of hospitalization, the total number of risk factors was more than the total number of patient.

The most common neurological symptoms/ sign were motor dysfunction [145 (51.4%)], altered sensorium [112 (39.7%)] and ataxic gait [98 (34.7%)]. [[Table 3]] A large number of patients presented with visual dysfunction/ diplopia [85(30.1%)], due to occipital lobe and brain stem involvement. The mean NIHSS score during presentation was 18.06 (±8.68).

All the patients, in our study, underwent MRI of brain which was reviewed by neuroradiologist. Infra tentorial stroke lesions were commoner than supratentorial lesions [158 (56.02%) v/s (92 (32.6%)]. [[Table 4]] The most common anatomical site of involvement was Cerebellum [86(30.5%)].

Large artery diseases (58.8%) were the most common aetiological causes according to TOAST Criteria. [[Table 5]]. Posterior cerebral artery territorial involvement was most common (43.6%), followed by PICA involvement (29.1%).[[Table 6]]

Patients were admitted in hospital for a mean of 11.4 (±6.13) days. Three patients were treated with intravenous thmbolysis (rTPA). Suboccipital decompressive craniectomy was done in 5 patients. All the patients were treated with antiplatelets (most common Aspirin 64.5%) and lipid lowering agent (most common Atorvastatin 66.6%) [[Table 7]]

Most common in hospital complications of stroke, were observed as electrolyte imbalance [52(18.4%)] followed by aspiration pneumonia [32 (11.3%)]. [[Table 8]] The mortality was noted in 18 (6.3%) patients in this study group.

Abbreviations: PCA- Posterior cerebral artery ; PICA- posterior inferior cerebellar artery; SCA- superior cerebellar artery; AICA-anterior inferior cerebellar artery; TOB- top of basilar artery

Discussion

The study was conducted in the department of medicine in collaboration with the department of neurology, Hi-Tech Medical college & Hospital, Odisha on 282 patients of posterior circulation ischemic stroke admitted over eighteen months duration.

We encountered posterior circulation ischemic stroke in 16.2% of total stroke patients in our study, as comparable to previous studies by Mehndiratta et al^[9] (11.3%), Richard et al^[10] (14.8%) and Jones.et al^[11] (17%).

In our cohort the incidence of posterior circulation ischemic strokes, below 60 years age group was 58.8% similar to an Indian study by Kora SA et al (56%).¹² These findings suggest posterior circulation ischemic stroke affecting the younger population in India. Incidence of stroke was more in males as compared to females (Male: Female - 2.27:1) which was in accordance with previous studies like Kora. S.A et al^[12] and R.B.Libman et al.^[13]

Incidence of infratentorial ischemic strokes was high (56.02%) as compared to supra tentorial lesions and use of MRI scan aided in identifying the infratentorial lesions promptly. CT scan is a poor diagnostic tool compared to MRI scan, especially for infratentorial lesions.^[14] The incidence was comparable to Bogousslavsky et al study (70%).^[15]

In our series, the incidence of HTN, Diabetes, hyperlipidemia and ischemic heart disease were higher, suggesting significant atherosclerotic risk factors. They were comparable with different studies by E.Ratnavalli et al,^[16] Capalan et al,^[17] Uma et al,^[18] Kora.S.A et al^[12] and Mehndiratta et al.^[9][[Table 9]]

 The clinical manifestations encountered in our study are comparable to the Kora SA et al ^[12] and Patrick et al ^[19] studies.[Table 10] The incidence of visual disturbance was higher in the present study (30.1%) compared to Patrick et al^[19] (13%) which can be due to the presence of larger number of occipital infarcts in our study (25.8% V/s 8%). The major clinical symptoms like motor weakness, vertigo, ataxia and cranial nerve deficits were attributable to the affection of brain stem, long tracts, cranial nerve nuclei and cerebellar connections. The varied clinical manifestations probably due to difference in infarct size, location, presence of collaterals and vascular territory involvement in different studies. In our patients, headache and vomiting were commonly seen as suggested by previous studies. ^[13] These symptoms are commonly seen, than in anterior circulation strokes. ^[13]

In our study, 58.8% patients had large artery disease and 15.6% had a cardio-embolic aetiology. Large artery disease stroke was present in 32% of patients in New England Medical Center Posterior Circulation Registry, while 24% had cardiac source of embolism. ^[20] Higher incidence of large artery involvement in our patients and in the study by Mehndiratta et al ^[9] could be due to the more frequent intracranial large artery atherosclerosis in Asians as compared to whites which has been suggested by many studies. ^[21], ^[22], ^[23]

The mortality noted in various studies were (25.6%) Patrick et al,^[19] (17%) Uma et al ^[18] and (27.5%) Jones et al ¹¹. Incidence of mortality (6.3%) in our series is less comparing with other studies, may be related to advancement in the neuro critical care and more number of mild to moderate strokes.

Limitation(s)

This study may not be a true reflection of posterior circulation stroke in the community since it has been undertaken in a tertiary care hospital and there can be a referral bias of presentation. Further studies would help to know more about the prognostic markers of mortality in posterior circulation stroke in relation to various risk factors and clinical features.

Conclusion

The present study from Eastern India describes the various risk factors, clinical manifestations, subtypes of stroke and management of posterior circulation ischemic strokes. Our study demonstrated the frequent occurrence of posterior circulation ischemic stroke in a relatively younger age group in India. There are higher percentages of large artery disease and low cardio-embolic strokes in our study cohort. Our study suggest that pattern of risk factors, stroke subtypes, vascular territory and lesion topography in posterior circulation strokes might have environmental, regional and ethnic variations.

Conflict of Interests

There are no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Source of Funding

The authors received no financial support for the research, authorship, and/or publication of this article.