An Unusual Presentation of Cerebrovascular accident in the bilateral ACA territory with Bacterial Meningitis and Miliary tuberculosis

Introduction

Though rare, it is important to recognize the anomalies of the cerebral circulation.  Several morphological variations of the circle of Willis exist. In the autopsy series reported by Hodes and colleagues, only 18% of specimens of the circle of Willis were found to be anatomically normal [1] and Krabbe-Hartkamp and coworkers reported that 42% of subjects showed a complete circle of Willis on magnetic resonance angiography.² Maurer et al reported that an anaplastic A1 segment was found in 0.3% to 2.0% of individuals.³ This is especially true of the anterior cerebral arteries (ACAs), as they supply blood to both the hemispheres.^4,5

Considerable variations occur in the origin and course of the ACAs. However, three distinct patterns are well recognised. The most common anomaly is the accessory ACA. The next most common anomaly is the bihemispheric ACA. The least common anomaly is the unpaired or azygous ACA, Complete infarction due to occlusion of one ACA distal to the anterior communicating artery results in a sensory-motor deficit of the opposite foot and leg and a lesser degree of paresis of the arm with sparing of the face.⁴

Case Report

A 50-year-old female was admitted to our hospital with a history of altered sensorium since 24 hours. It had begun as sudden onset aphasia with bowel and bladder incontinence. Attenders reported that there was no history of any loss of consciousness, headache, nausea, vomiting, or convulsions. Past history was not contributory, and the patient did not exhibit any vascular risk factors.

Routine full blood count and biochemical analysis were normal. Cranial computerised tomography (CT) demonstrated presence of a bilateral ACA territory infarct, and the patient was managed with conservative treatment,initially the patient was put on with ryles and folleys catheterization, and started withinjcefixime 1gm iv bdinjmannitol iv tidinjpantaprazole 40 mg iv od injemeset 4mg iv tid.

On examination, the patient was found conscious, irritable with of GCS of 9/15 eye opening spontaneous, Verbalresponse confused, Motorresponse withdrawal. The patient had aphasia, with no significant limb weakness, suggestive of frontal lobe disruption. MRI was done as in keeping with the initial suggestion ACA Infarct. Given the sudden onset of her symptoms, the possibility of vascular aetiology was considered. Magnetic resonance imaging with MR Angio (MRI + 3D TOF) revealed acute infarct in bilateral parafalcine area, lacunar infarct in left middle cerebellar peduncle and right corona radiata, hypoplastic right vertebral artery, mild focal stenosis of bilateral A2 segments of ACA [images 1-4).This finding reinforced the clinical suspicion of a bifrontal infarction and no neurosurgical intervention was proposed.

The patient improved drastically over a period of 2 weeks with low molecular weightheparin 40mg scbd, for 5 days and dual antiplatelet therapy tab clopidegrel 75mg aspirin 150mg po od. The patient was on the verge of discharge when shewent into altered sensorium again with loss of speech and loss of balance. A repeat CT was performed and it showed areas of bi frontal hypodensities in parafalcine areas in addition to previous findings.

On vigorous history extraction with family persons, it was found that the patient was having intermittent fever and cough since 2 months for which she was taking treatment with local doctor. Evaluation with CT Thoraxshowed features suggestive of miliary tuberculosis with incidental findings of multiple enlarged peri pancreatic and peri portal lymphnodes, though the baseline chest xray done had no significant findings  CSF analysis showed protein: 94.2 mg%[N 15-45 mg%], sugars :41 mg% [N 45-80%] and  25 cells (all lymphocytes).

The patient was then managed conservatively with osmotic diureticsinjmannitoltid, IV steroids injdexona 4mg ivtid with tapering and first line Anti tuberculosis drugs based on weight. The patient made a gradual recovery. Aphasia showed slight recovery. However imbalance was persisted. The patient was discharged with first line  Anti-tuberculosis drugs, anti oedema drugs (syp glycerol 10ml tid) oral steroids  with tapering (tab methylprednisolone) dual antiplatlets(tab clopidigrel 75mg tab od aspirin 150mg od tab atorvastatin40 mg hsand was adviced for regular follow ups.

Discussion

The ACA is a major vessel responsible for the blood supply to the inter-hemispheric regions. Infarction of the ACA territory accounts for only 0.3% to 4.4% of cerebral infarctions reported.^6,7 Bilateral ACA infarction is even rarer. Twenty-seven cases of ACA territory infarction were reported among 1490 cases of cerebral infarction in the Lausanne Stroke Registry; however, there were only two cases of bilateral ACA territory infarction.⁸

Baptista.⁹ defines a bihemispheric ACA as one, which in its initial portion furnishes branches only to the homolateral cerebral hemisphere and then, at some point in its further course sends, one or more branches across to supply the opposite cerebral hemisphere.⁵ He has further sub-classified them into eight sub-groups, based on the different variations. However, our patient does not fit into any of these sub-groups as no portion of the right ACA was visualised on angiography (Fig. 3, 4), signifying that our patient had a rudimentary or an aplastic middle cerebral artery.

Incontinence and gait aplaxia are two of the commonest manifestations of ACA territory infarction. However, the clinical picture depends on the location and size of the infarct, which in turn relates to the site of occlusion, the pattern of blood flow through the circle of Willis and other ischaemia-inodifying factors.

Unilateral occlusion of the stem of the ACA proximal to its connection with the anterior communicating artery is usually well tolerated since adequate collateral flow comes from the ACA of the opposite side. Maximal disturbance occurs when both arteries arises from one ACA stem, in which case there will be infarction of the medial parts of both the cerebral hemispheres. This produces Para paresis; with weakness more marked peripherally, urinary incontinence and aboulic and aphasic symptoms. These patients lie in bed unwilling to initiate any voluntary movement including speaking, appear to watch other people by following them with their eyes, take food and drink only if it is placed in their mouth and make sucking noises and chewing movements but otherwise seem uninterested in their surroundings.

According to Bogousslavsky and Regli, 63% of ACA infarctions result from cardiogenic emboli or arteryto-artery emboli.⁸ Gacs et al. reported other causes such as  unilateral occlusion of the internal carotid artery (ICA), distal extensions of ICA thrombosis and local thrombus by vasculitis.⁷ Bilateral ACA territory infarction is usually due to vasospasm that occurs as a complication of subarachnoid haemorrhage following rupture of one or more aneurysms of the anterior communicating arteries or distal ACAs.⁶  However, in the case of an anomaly in the anterior part of the circle of Willis, thrombosis or embolism can lead to bilateral infarction.

Anomalies of the ACA are not rare as was previously believed. Baptista demonstrated anomalies of the ACA in 25% of the brain specimens studied.⁹ Considerable variations occur in the origin and course of the ACA (6).⁸ However, three distinct patterns are well recognised: accessory ACA, bihemispheric ACA and unpaired or azygousACA (6). The true incidence of bilateral ACA infarction is unknown, with few cases are reported in the literature. In 2004, Yamaguchi et al reported a similar case with a patient presenting with lower limb weakness and magnetic resonance angiography had demonstrated bilateral anaplastic ACAs.⁵

In our patient, MR Angio demonstrated a hypoplastic left ACA and branches of the right ACA supplying part of the left frontal lobe Serial CT scans confirmed that this was indeed a case of infarction with bacterial meningitis with military tuberculosis. If investigations were not performed to confirm or exclude the clinical suspicion Tuberculous meningitis despite the findings of the initial cranial CT, a diagnosis of bacterial meningitis and miliary tuberculosis would have been delayed or missed and the patient might have had to undergo an unnecessary complication. However, it should be noted that other investigations such as CT Thorax and CSF Analysis, if performed during the time of presentation could have resulted in an accurate diagnosis more acutely.

Conclusion

This case report highlights that simultaneous bilateral cerebral infarction can be the result of a unilateral cerebral artery occlusion It also demonstrates that anomalies of cerebral vasculature are not as rare as is usually believed, and this should be borne in mind while investigating unusual presentations of cerebrovascular infarction.