Keywords
tuberculosis - intraspinal extradural lesion - without osseous involvement
Introduction
Spinal tuberculosis (TB) comprises nearly 50% of the skeletal TB.[1]
[2] Most frequently involved are the upper lumbar and lower thoracic spine. Spinal TB
is characterized by destruction of the intervertebral disc space and adjacent vertebral
bodies, collapse of the spinal elements, and anterior wedging leading to the characteristic
angulation and gibbus (palpable deformity due to involvement of multiple vertebrae)
formation. The neurologic manifestations of spinal TB are most often secondary to
bone involvement but can also be due to neural and per ineural tissues involvement,
that is, epidural space, subdural space, meninges, or cord tissue directly. Intraspinal
extradural tubercular lesion is a rare cause of compressive spinal cord lesion, and
especially infrequent is an isolated granuloma without vertebral involvement.[3]
[4] Interestingly, no study has explained the reasons for this localized involvement.
We reported an uncommon case of isolated intraspinal extradural tuberculous lesion
without osseous involvement of the thoracic spine.
Case Report
A 21-year-old adult man presented at the neurosurgery OPD with complaints of backache
in the mid-thoracic region since 1 to 2 months and progressively increasing weakness
in both the lower limbs since 15 to 20 days. There was no history of trauma, fever,
chronic cough, weight loss, and antituber cular treatment (ATT). No bowel and bladder
complaints were present. No significant family history of Koch's was present. On physical
examination, slight tenderness was present in the upper thoracic region and sensory
loss was found below D6 spinal level. Power in both the lower extremities was 2/5
with normal muscle tone. Deep tendon reflexes (DTRs) in both the lower limbs were
hyperactive. Babinski's sign was positive. Routine laboratory examination was within
normal limits, except erythrocyte sedimentation rate (ESR) that was 25 mm/h. Conventional
radiograph of the chest and dorsolumbar spine were normal, without any evidence of
vertebrae destruction. Magnetic resonance imaging (MRI) of the spine showed relatively
well-defined T1 isointense intraspinal extradural mass lesion measuring 4 cm × 3 cm
at D6 vertebral level, causing mass effect on adjacent thoracic spinal cord evident
by anterior displacement and compression without obvious cord signal intensity changes.
Minimal postcontrast enhancement of mass was seen in T1 contrast ([Fig. 1]). No extension into bilateral neural foramina or bony involvement, no obvious sign
of arachnoiditis, or bone marrow altered signal changes were noticed. Mid-saggital
T2 images showed mildly hyperintense mass lesion posterior to the spinal cord at D6
level causing mass effect on cord. MRI features were suggestive of possibility of
either nerve sheath tumor or inflammatory granuloma.
Fig. 1 (a) Magnetic resonance imaging of spine showing mid-saggital T2 images showing mildly
hyper intense mass lesion posterior to spinal cord at D6 level causing mass effect
on cord. (b) Axial section with T1 isointense intraspinal extradural mass lesion at D6 vertebral
level. (c) Axial section with postcontrast enhancement of lesion in T1 contrast.
The patient underwent D5–D6 laminectomy and excision of lesion. Intraoperatively,
posterior elements of the dorsal spine were intact, and the mass was totally extradural,
adhered to the spinal dura mater. Lesion was gently separated from the dura mater
and excised ([Fig. 2]). Lesion size was around 4 cm × 2 cm and sent for histopathologic examination and
microbiological culture. The cultures of the biopsy specimen were negative for anaerobes,
fungi, and mycobacteria. Histopathologic investigation revealed chronic inflammation
and ill-formed granulomas embedded on a fibrocollagenous tissue ([Fig. 3]). Great sheets of delicate vessels lined by a flattened endothelium and separated
by scant connective tissue stroma were also observed. The patient was con tinued on
ATT empirically. Neurologic symptoms improved, and he was discharged with moderate
neurologic deficit. On follow-up, he showed remarkable improvement.
Fig. 2 (a) Lesion after D5–D6 laminectomy showing extradural lesion adhered to the spinal dura
mater. (b) Excised lesion. (c) Whitish spinal dura mater after lesion excision.
Fig. 3 (a) Microphotograph showing scattered ill-formed granulomas embedded on a fibrocollagenous
tissue (H&E, 100X). (b) Microphotograph showing high-power view of ill-formed granuloma (H&E, 400X).
Discussion
Tuberculosis continues to be a major public health prob lem in developing countries
despite widespread national TB programmes. Approximately 10% of patients with extrapulmonary
TB have skeletal involvement. The spine is the most commonly affected skeletal site,
followed by the hip and knee.[5] TB of the spine comprises approximately 25 to 60% of all osseous infections caused
by TB.[6]
[7]
Owing to nonspecific history and widely varying spectrum of clinical features, its
diagnosis needs special attention. Fever and systemic symptoms may not become evident
until the late stage. Almost one-half of the patients with extrapulmonary TB have
normal chest X-ray findings.[8] ESR, though nonspecific, is found to be elevated in most cases.
Tuberculosis may involve any level from the cervical to lumbosacral region.[9] Extradural tubercular granuloma without vertebral involvement is uncommon. Also,
isolated intraspinal TB without radiologic evidence of vertebral involvement is rather
uncommon. Kumar et al reported 22 cases with intraspinal TB, in which 3 out of 12
cases with extradural granulomas were without osseous involvement.[10] We reported another such similar case of tubercular granuloma in an adult male without
vertebral involvement of the thoracic region.
Among spinal TB, isolated intraspinal TB with absence of vertebral destruction and
with neural deficit is less than 5%.
Multiple imaging modalities such as conventional radiography, scintigraphy, computed
tomography (CT), and myelography have all been reported to be helpful in the diagnosis
of spinal TB, but MRI is relatively more sensitive and is believed to be the modality
of choice.[11]
[12]
The final diagnosis is established by histologic examination. It is suggested that
tubercular granuloma should be considered in the differential diagnosis when a case
of spinal tumor syndrome is encountered in an endemic area of TB. Without losing the
precious time, ATT should be started when the investigations are awaited to avoid
treatment delay and the patient be monitored timely.
As per the “Standards for TB Care in India” guidelines by the World Health Organization
(WHO), all new patients should receive an internationally accepted first-line treatment
regimen. The initial phase consists of treatment with isoniazid (H), rifampicin (R),
pyrazinamide (Z), and ethambutol (E) for 2 months followed by the continuation phase
comprising three drugs H, R, E given for at least 4 months. Owing to risk of disability
and mortality and difficulties in assessing the treatment response, WHO recommends
that the duration of continuation phase may be extended by 3 to 6 months in special
situations such as bone and joint TB, spinal TB with neurologic involvement, and neurotuberculosis.[13]
Surgical intervention along with ATT is one of the preferred treatments for intraspinal
extradural tubercular lesion. Combination of microsurgical resection and antitubercular
chemotherapy provides promising results. Similar were the suggestions by Türeyen regarding
optimal treatment for isolated intraspinal extradural tubercular lesion.[14] With this treatment plan, patients usually show good neurologic recovery after adequate
surgical decompression and necessary antitubercular treatment. In this case also,
the patient showed good neurologic recovery with this treatment modality.
Although isolated intraspinal extradural tubercular lesion without osseous involvement
is an uncommon entity, but it should be kept in mind as a possible differential diagnosis
in cases of extradural spinal lesions.
