Hybrid PET/MRI findings in a case of pulmonary and extra-pulmonary tuberculosis associated with motor-neuron disease-like illness—a coincidence or a causation?: a case report

The association of tuberculosis and motor neuron disease-like illness has not been described previously. We present a case of co-existent pulmonary and extra-pulmonary tuberculosis in a young man whose clinical presentation was suggestive of a motor neuron disease-like illness and was subsequently diagnosed with tubercular infection. This case provokes our thought as to whether the association between tuberculosis and motor neuron dysfunction was just a co-incidence, given the high prevalence of tuberculosis in our set-up, or does it point towards a possible causative role of infection in motor neuron disease. A 31-year-old man presented with progressive thinning of bilateral upper and lower limbs with associated pain and twitching sensation in upper and lower limb muscles. He had a history of loss of appetite and unintentional weight loss. On clinical examination, there was evidence of fasciculations in bilateral quadriceps, bilateral biceps, and paraspinal muscles which was further confirmed with electrophysiology. The work-up for underlying autoimmune, toxic and metabolic aetiology, and paraneoplastic aetiology was found to be negative. CT scan of the chest was suggestive of consolidations in bilateral upper lobes with multiple tree-in-bud nodules in both the lungs. Hybrid 18-Flourine-flourodeoxyglucose positron emission tomography and magnetic resonance imaging (F-18-FDG PET/MRI) imaging was also suggestive of pulmonary and extra-pulmonary tuberculosis. Imaging of the brain revealed atrophy along bilateral motor cortices with reduced tracer uptake. Diagnosis of tubercular infection was confirmed with nucleic acid amplification test and the patient was put on anti-tubercular therapy. On follow-up after 6 months, the patient reported improvement in the symptoms and the muscle power in bilateral upper and lower limbs. We have described a very rare association of pulmonary and extra-pulmonary tuberculosis with motor neuron-like illness. It may be debated that such an association may just be co-incidental; however, given the improvement in the symptoms and signs of the motor neuron disease-like illness on follow-up while the patient was on anti-tubercular therapy, it may point towards a causative relationship between tubercular infection and motor neuron dysfunction. Further epidemiological studies should be sought for in order to reach a conclusive answer.