DISCUSSION:
Tuberculosis (TB) remains a common health issue in developing countries even though TB has not been seen widely as before [6]. Osseous TB involvement may account for up to 35% of patients with extrapulmonary TB, and vertebral osteomyelitis infections (Pott’s disease) account for 25–60% of all osseous infections caused by TB [7-9]. Approximately 10% of patients with extrapulmonary tuberculosis (TB) experience central nervous system (CNS) involvement, typically resulting from the bacteremic stage of the disease. During this stage, tuberculous lesions known as Rich foci may develop in the meninges or within the brain or spinal cord tissue [10,11]. After several months or even years, these foci can rupture into the cerebrospinal fluid, leading to meningitis, or they can enlarge and form tuberculomas within the brain or spinal cord parenchyma,
The Mycobacterium bacilli can also spread hematogenously to various parts of the body, including the brain, due to minor bacteremia. The pathogenesis of central nervous system tuberculosis involves the development of small foci of tuberculosis, known as Rich foci, in the brain, spinal cord or meninges [10]. Earlier studies by Rich and McCordock showed that TBM requires direct inoculation of the bacilli through a meningeal focus in the central nervous system. However, later studies showed that disseminated tuberculosis plays a crucial role in the development of tuberculosis [12]. Tumor necrosis factor alpha (TNF-α) is a critical cytokine in M. tuberculosisneuropathogenesis. Although it helps in granuloma formation and control of mycobacterial infections, local production of TNF-α in the central nervous system can alter the permeability of the blood-brain barrier and promote the progression of TBM [13].
M. tuberculosis has a unique ability to enter and multiply in macrophages. Human microglia are selectively infected by M. tuberculosis and the CD14 receptor facilitates engulfment of unopsonized bacilli by microglia. Microglia infected with M. tuberculosis produce a variety of cytokines and chemokines, including TNF-α, IL-6, IL-1β, CCL2, CCL5, and CXCL10. Microglia play a central role in the neuropathogenesis of tuberculosis, and their infection can lead to immunosuppressive effects, especially in more virulent strains [14].
Tuberculous meningitis is the most common form of central nervous system (CNS) tuberculosis (TB) compared to tuberculomas. Similarly, among various forms of spinal TB involvement such as Pott disease, non-osseous spinal TB, tuberculous spinal meningitis, and tuberculous arachnoiditis, non-osseous spinal tuberculoma is infrequent. In a review conducted by Dastur, 74 cases of spinal tuberculomas were analyzed, revealing that 65% were located extra-durally, 8% were intramedullary, 5% were intradural extramedullary, and 20% were arachnoidal [15-17]. Non-osseous spinal tuberculomas typically originate from a primary pulmonary focus, spreading hematogenously or through direct extension from hilar lymph nodes [18]. In our case, a rare and unexpected involvement occurred in the form of a non-osseous intradural extramedullary (IDEM) tuberculoma of the spinal cord, resulting in paraparesis despite the patient receiving antitubercular therapy (ATT). To our knowledge, this is the first reported case of a tuberculoma at the juxta-medullary location in the thoracic region.
The clinical presentation of the case aligns with the findings reported in the literature, which often show a higher prevalence among males [19]. The most common presentation in our case was spastic paraplegia, post-ATT liver failure, and respiratory problems associated with tuberculosis and COVID-19. Nevertheless, tuberculomas are slow growing with areas of necrosis that are encapsulated, avascular, and infrequently calcification. Our patient exhibited involvement of the thoracic spinal cord, which aligns with the reported incidence of up to 70% of cases in the literature. The thoracic spine is the most frequently affected site in Pott’s syndrome [20]. The radiological imaging findings of tuberculomas can vary depending on the stage of the lesion. On MRI, tuberculomas may present with non-caseating granulomas or caseating granulomas characterized by a solid or liquid center [21]. The tuberculous lesion typically appears isointense on T1W images, isointense to hypointense on T2Wimages, and exhibits ring enhancement with a hypointense center on gadolinium-enhanced MR scans. As the lesion undergoes caseation, the center becomes bright and gives rise to a target sign, as observed in our case [22-24].
A combination of surgical intervention and medical treatment has shown excellent outcomes. While some authors argue that anti-tuberculous therapy alone is sufficient when a paradoxical reaction develops into a tuberculoma [25,26], a literature review on intradural extramedullary spinal tuberculoma confirms the limited effectiveness of medical therapy alone and highlights the need for surgical intervention [27-33]. The reason for the poor response to chemotherapy in this condition remains unclear. Therefore, we believe that surgery is warranted when intradural extramedullary spinal tuberculoma arises as a paradoxical response to therapy.
The list of similar published cases is mentioned in Table 1: