Spinal tuberculosis and atypical infections

Spinal tuberculosis

Incidence

Until recent AIDS epidemic a rare disease in the first world


M > F


Most common level L1

Aetiology

Mycobacterium tuberculosis

Pathology

Usually a secondary infection – primary lesion in lung, GIT or GUT

Rarely spine involved in direct spread from other structures

The infection begins in the paradiscal vertebra.

Infection tends to spread across the periphery of the disc – to involve the metaphyses of the vertebrae above and below.

It is typical to see more than one vertebra involved.

The ant and post longitudinal ligs and periosteum are stripped up, arteries thrombose and bone dies as well being directly destroyed by the granulomatous process

The disc, being relatively avascular is relatively spared and destroyed late in the disease

Thus progression:          granuloma formation


pus production +/- abscess formation


bone loss, death +/- collapse


neuro involvement may be seen in active or healed disease

Active disease à pressure from pus, granuloma, bony sequestra, disc material, bony collapse


Can get TB meningitis or meningomyelitis


Healed disease à due to internal bony bridge or fibrous tissue constriction

Clinically

Depends on stage of disease


General -fever, malaise, weight loss

Evidence of TB elsewhere

Local –rest pain, worse with motion ,muscle spasm, deformity, sinus

Neurological -“Pott’s Paraplegia”

Deformity progression occurs in two distinct phases

Phase I – changes in the active phase

Phase II – changes after the disease is cured

Investigation –    

Bloods:

WCC, ESR, CRP

Mantoux:

Radiology: 

CXR

Plain films

CT

MRI –  sensitivity of 100% and specificity of 88%

Biopsy: Z-N staining of material high yield in active disease, poorer in healed disease

Diagnosis

Combination of the above


DDx other infection, neoplasia


Healed TB can resemble congenital fusions

Treatment

Medical

Triple therapy:    

Streptomycin: initial 2-3 mths

Isoniazid: 9 mths


Rifampicin: 9 mths

Nonsurgical treatment alone –

Patients with early disease

Minimal bone involvement

Medical contraindications to operation

Therapeutically refractory cases of tuberculosis of the spine are increasing in association with the presence of HIV and multidrug-resistant tuberculosis.

Surgery

Kyphosis of 60 degrees or more, or one which is likely to progress

Anterior decompression, posterior shortening, posterior instrumented stabilisation and anterior and posterior bone grafting in the active stage of the disease

Internal kyphectomy (gibbectomy) –  late onset paraplegia with severe healed kyphosis.

Advantages of surgery –


prevention of progression of abscess


relieve pressure on neural tissue


graft under compression – fusion almost sure- thus late kyphosis prevented

Complications

Neurological deficit – paraplegia/quadriplegia

Deformity