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|NI FEATURE: THE EDITORIAL DEBATE-- PROS AND CONS
|Year : 2016 | Volume
| Issue : 5 | Page : 868-870
Tuberculous vasculitis: The neurosurgeon's perspective
Department of Neurosurgery, G.B. Pant Institute of Medical Education and Research, New Delhi, India
|Date of Web Publication||12-Sep-2016|
Department of Neurosurgery, G.B. Pant Institute of Medical Education and Research, New Delhi
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Jagetia A. Tuberculous vasculitis: The neurosurgeon's perspective. Neurol India 2016;64:868-70
Tuberculous cerebral vasculitis (TCV) is a devastating sequel of tuberculous meningitis (TBM) if the latter is not adequately treated in a timely manner. The incidence of TCV is estimated to be between 6 to 41% in patients with TBM, and brainstem involvement is seen in 4.5% of pediatric and adult population. The etiopathogenesis of TCV is pan-arteritis of the basal arteries of circle of Willis and also of the lenticulostriate arteries. It usually occurs due to an inflammatory reaction within the subarachnoid spaces and basal cisterns, leading to vasculopathy and steno-occlusive changes with precipitation of ischemic events. It can occasionally involve capillaries and veins. The other mechanisms, leading to vascular narrowing, may be vessel infringement by the inflammatory exudate, or vasospasm mediated by the vascoconstrictive substances.
Historically, if symptoms of tuberculous meningitis are persisting with the additional appearance of new neurological signs and symptoms, or with a deteriorating neurological status even when the patient is receiving adequate anti-tuberculous treatment (ATT), the diagnosis of TCV should be suspected. The international Haydarpasa -3 study done by Cag et al., states that a delayed fever response also strongly suggests the presence of TCV. A persistently deteriorated neurological status, especially when other causes such as hydrocephalus and convulsions have been excluded, also points towards the existence of TCV.
The confirmatory diagnosis of the presence of TCV can only be established in the post-mortem examination by the histopathological study of vessels. Various imaging modalities such as the computed tomographic (CT) or magnetic resonance (MR) scan, magnetic resonance angiogram (MRA) or the digital subtraction angiogram (DSA) may, however, be helpful in patients suffering from different stages of the disease. These investigations may reveal infarcts, basal exudates, tuberculous abscesses, beaded appearance of arteries as well as narrowing of arteries at the skull base.
The risk factors for the development of TCV reported in literature include the female gender, the concomitant presence of human immunodeficiency virus syndrome, a prolonged duration of pre-existing symptoms, the presence of hydrocephalus, a high persisting cerebrospinal fluid neutrophil count, the meningeal enhancement on initial brain imaging, the presence of stage II or III of meningitis, and the presence of tuberculomas. Vascular endothelial damage, stasis and hypercoagulability act synergistically to cause vascular thrombosis. Therefore, treating the risk factors can avoid the occurrence of TCV.
Early imaging to observe the vessel changes and to ascertain the ischemic changes is helpful in preventing TCV. An early imaging protocol, however, is not very practical to implement due to the lack of easy accessibility and the high cost of imaging in the emergency setting. Under these circumstances, one has to rely on clinical examination to ascertain the presence of TCV.
Treatment options for TCV involve both general as well as specific recommendations. Large-sized tuberculomas at non-eloquent locations may be safely excised; this could also have a bearing in combating the development of TCV. Maintaining adequate hydration in these patients, especially in children, is a big concern to avoid an aggravation of TCV, as these patients receive many dehydrants during the course of their illness to decrease their intra-cranial pressure.
Hydrocephalus should be addressed in a timely manner, either by medical therapy (by administration of acetazolamide, frusemide and/or mannitol), or by surgery in the form of a ventriculoperitoneal shunt or an endoscopic third ventriculostomy. Based on the modified Vellore grading of tuberculous meningitis and hydrocephalus, medical management could be tried for a few days or a week in patients in grades I and II (better grade) with close monitoring for any deterioration; and, a shunt should be promptly offered in the cases that have a failure of medical management. This is because the outcome is better with an early surgery. Prolonging medical therapy in patients in a good grade could be harmful and may lead to an irreversible brain damage. The institution of early surgery for obstructive hydrocephalus and medical therapy for communicating hydrocephalus has often been suggested. Singh et al., reported a success rate of 77% following an endoscopic third ventriculostomy among 35 patients with TBM associated with hydrocephalus, where 60% patients had an early, and 17%, a delayed recovery.
A cytokine-mediated inflammatory response causes vasculitis, and tumor necrosis factor alpha (TNF-alpha) is an important cytokine in this response. Due to the important role of inflammation in the genesis of this entity, corticosteroids are routinely used to reduce death and the disabling neurological deficits among survivors. Dexamethasone 1 mg/kg/day in a tapering dose over 4-6 weeks, or prednisolone starting with a high dose (60 mg) that is gradually reduced over 6 weeks, may be given. The latter medication may then be stopped or continued as a low dose (5 mg) regimen, depending upon the patient's condition. The advantages of the adjunctive corticosteroid therapy with ATT over the standard ATT therapy alone, are an increased survival rate and a reduction in the sequel of TBM. Thalidomide is a drug with pleiotropic effect that also downregulates the production of TNF-alpha and other proinflammatory cytokines. Due to its anti-inflammatory effects, thalidomide has been evaluated as an adjunctive medication in the management of difficult-to-treat central nervous system tuberculosis; however, it is reserved for cases refractory to corticosteroids and may be used as a “salvage therapy.”
Once the TCV sets in, treatment should include the combination of the 4 agent regimen, as is the standard for the treatment of tuberculous meningitis, which includes isoniazid, rifampicin, ethambutol, and pyrazinamide. Addition of antiplatelet-aggregating agents, as is used in the acute phase of non-infective ischemic strokes, does not prevent the development of recurrent ischemia. The procedure, however, lowers the risk of death and neurological sequel of TBM with TCV. Surgical treatment may follow the pattern of management utilized in non-infective ischemic strokes, which includes cerebral blood flow augmentation procedures. There is, however, scanty literature (only in the form of case reports) on the management of TCV. Thus, large randomized trials are required in the future to unequivocally establish the treatment protocol for this entity. This protocol includes both the endovascular as well as the exovascular procedures. The endovascular treatment includes angioplasty using inflatable balloons or stent placement. Exovascular procedures include both the direct (the arterial bypass technique) as well as the indirect bypass procedures (such as encephalomyosynangiosis or encephalomyodurosynangiosis and the multiple burr-hole technique).
In a case reported by Martin et al., of a 5-year old girl, TCV manifested after an year of her presentation with tuberculous infection in the form of multiple tuberculomas, involvement of roof of the fourth ventricle, and contrast enhancement of basal arteries, She presented with delayed and repeated transient ischemic events, treated by repeated endovascular treatment in the form of transluminal angioplasty, stent placement in the middle cerebral artery (MCA), and followed later by in-stent balloon angioplasty under the cover of pentoxyphylline and clopidogrel, which were subsequently changed to aspirin alone. Her ischemic episodes were finally managed by superficial temporal artery – MCA bypass. The neuropsychological status of these patients needs to be thoroughly assessed in order to enhance their quality of life after undergoing such extensive procedures to improve the cerebral circulation. In childhood tuberculosis, the negative predictors for the neurodevelopmental outcome are a younger age, unilateral multiple or bilateral infarctions seen on CT scans at 1 month, and an advanced stage of tuberculous meningitis
To conclude, TCV can develop despite treatment with antituberculous drugs, corticosteroids, and aspirin. Corticosteroids are the cornerstone of therapy for TBM with TCV and should be prescribed in combination with anti-tuberculous regimens to treat TBM. Preventive measures should help in avoiding the development of TCV. Randomised control trials are required to establish the role of cerebral blood flow augmentation procedures in improving the quality of life in these individuals.
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