Spinal tuberculosis: A neglected disease?

Spinal TB (STB) has been demonstrated in mummies from the ancient Egypt and Peru, ^[1] but it was first described by an extraordinary surgeon of the XVIIIth. century, Sir Percival Pott (1714-1788) who published the description of paraplegia associated to “a curvature of the spine”. His contributions to medicine include, among others, the description of a special wrist fracture, known as Pott’s fracture and a major contribution to the public health: the relationship between coal tar and cancer of the scrotum among chimney sweeps. ^[2]

Extrapulmonary tuberculosis (EPTB) does not deserve the same attention by the TB control programmes as the pulmonary TB due to its low infectivity. Moreover, cases of extrapulmonary TB are usually notified all together, so there is a lack of epidemiological information about the incidence of its different presentations; specifically in relation to spinal tuberculosis (STB), mainly isolated case series are published, highlighting clinical and therapeutic issues.

According to the WHO global TB report 2010, ^[3] the global incidence of EPTB is 14%, with higher proportions in the Eastern Mediterranean Region (18.9%) and African Region (18%). In the 8 African countries belonging to the 22 TB high burden countries (WHO) the average proportion of EPTB is 20.9%. From the 80’s, HIV infection has been considered a determinant factor in the incidence of extrapulmonary and disseminated TB.

Scarce information is found in the bibliography about the magnitude of STB among EPTB, considered the most frequent among bone and joint TB. In the USA, the proportion of bone and joint TB during the period 1993-2006 was 11.3% (28,600 cases); ^[4] other publications from countries with higher prevalence of TB reported a concomitant higher incidence of this EPTB.

In this issue of the Journal the article by Corti et al described the experience in spinal TB in HIV positive and negative patients admitted in a Argentina Infec­tious Diseases hospital. Out of the clinical manifestations (back pain, consumption and neurological manifestations) an important consideration is the delay in the diagnosis of a chronic back pain which implicates a greater possibility of severe neurological complications, such as paraplegia

If the STB is associated with pulmonary TB, the suspicion of Pott’s disease related to thoracic or lumbar pain is great, but in the absence of pulmonary compromise often the retard in the diagnosis is very important (in this paper, a mean of 120 days, with a maximum of one year). The initial involvement of the disc and vertebral body without para-vertebral tissues compromise and epidural, psoas or inguinal cold abscesses is easier to treat medically and the possibility of espondylolisthesis is minimal. Over time, the disease has a local progression and neurological complications with its subsequent sequelae are more frequent. Abou Raya diagnosed STB in Alexandria in 12 among 40 elderly patients presenting to medical consultation with backache. ^[6]

The magnetic resonance imaging is a mainstay of the imaging diagnosis together with CT and ultrasonography, but the cornerstone of the diagnosis of Pott’s disease is the isolation of the Mycobacterium tuberculosis from punctures of the spine or related abscesses. Mycobacteria and mycoses can be ethiological agents of a Pott like disease and primitive or metastatic cancer use to be more frequent than the Pott’s disease itself.

Another interesting observation of the authors is related to migrations and Pott’s disease. The incidence of EPTB is linked to that of TB in the country of origin. Developed countries consider the migration of countries with a high TB prevalence as a risk factor for EPTB. ^[2]

About the medical treatment of STB, the regimen is the same that for pulmonary TB (an initial phase of two months with isoniazid, rifampicin, pirazinamide and ethambutol followed by a continuation phase based on isoniazid and rifampicin). There is some discordance about the duration of the second phase: even though there is evidence of the effectiveness of a 6 month regimen for pulmonary and EPTB, ^[7] many experts consider that Pott’s disease (like meningitis or disseminated TB) needs a longer continuation phase: from 7 to 9 months. Additional therapeutic measures are the immobilization of the spine (a controversial issue), kinesiological rehabilitation and, if necessary neurochirurgical procedures.

Pott’s disease is a severe presentation of TB that affects mainly thoracic and lumbar spine usually with an important delay in the diagnosis, fortunately for its poor prognosis the cervical compromise is less frequent. The diagnosis requires a high degree of suspicion, and the burden of the disease is proportional to the TB prevalence. As Nioku concludes, ^[8] once been diagnosed, the effective management of STB requires a teamwork involving the physician trained in TB treatment, orthopedic surgeon, neurosurgeon as well as the radiologist.

DOI: 10.4103/1755-6783.109261