Entrapment neuropathy secondary to tubercular abscess: Uncommon presentation of a common disease.

Dear Sir,

Entrapment neuropathy due to nerve abscess secondary to Hansen's disease is common in South-East Asia and Indian subcontinent, but till now there is no report of entrapment neuropathy secondary to tubercular nerve abscess. Many such cases empirically treated as Hansen's disease. Hence a high index of suspicion is required in all such cases. Here we are reporting a case of a 30-year-old male farmer who presented with cord-like swelling over medial aspect of right arm, tingling sensation on ulnar aspect of forearm, difficulty in making fist and associated fever and loss of appetite and weight for 6 month. Past history of treatment for pulmonary Koch's was taken 8 year back.

Examination revealed pallor, a single 1.5-cm posterior cervical lymph node, significantly thickened cord like right ulnar nerve (Cold abscess) extending 3.0 cm above and 7.0 cm below medial epicondyle [Figure 1]., weakness of finger adduction along with poor handgrip, diminished pain and touch sensation on ulnar aspect of right forearm along with partial clawing of little and ring finger, wasting of muscles of hypothenar eminence. Routine haematological investigation showed microcytic hypochromic anaemia, relative lymphocytosis, and monocytosis and elevated Erythrocyte sedimentation rate (48 mm/hr). Human immunodeficiency virus-Enzyme linked immunosorbent assay and X-ray chest was negative. Montoux test was positive (12 mm). Ultrasonography of lesion revealed hypoechoic area of 5.1 × 2.7 × 1.2 cm with two central echogenic lines suggestive of perineural cold abscess with septa. Diagnostic aspiration done and microscopic examination of purulent material showed acid-fast bacilli bacteria suggestive of tubercular abscess. Nerve conduction study of patient showed not recordable of motor and sensory potential in right ulnar nerve.

Figure 1

Tubercular abscess of right ulnar nerve extending 3.0 cm above and 7.0 cm below medial epicondyle

Neurological involvement in tuberculosis can occur due to disease itself or as an adverse effect of therapy.[1] Peripheral nerve involvement in tuberculosis is either due to compression by cold abscess and vertebral collapse or toxicity of anti-tubercular drugs primarily isoniazid and pyridoxine. According to Kornilova et al., Mono and polyneuropathy of predominantly the lower extremities are frequently detectable in tuberculosis. However, concomitant alcoholism, diabetes mellitus, and isoniazid treatment make their course poorer.[2] A case of tuberculous radiculitis in the lumbosacral region resulting in flaccid paresis of the lower limbs has been reported by Myllylδ et al.,[3] Neuropathy due to tubercular abscess per se till now is not reported, but involvement in cases of tuberculosis is rarely reported. One such case was reported by Naha et al., where patient had disseminated tuberculosis with sensory neuropathy of both lower limbs.[4] After 4 months of treatment, swelling over the nerve and the neck lymph node subsided. Patient was advised for regular follow-up and to take full course of anti-tubercular treatment.

Thus to conclude, because the disease is potentially curable, any patient from a developing country particularly of South-East Asia and Indian subcontinent who presents with such an illness must be evaluated for tubercular aetiology, so that early treatment can be done and complications can be prevented.