2. Progression and Diagnosis
Two weeks later the patient was re-admitted with ataxia, gait disturbance and loss of power bilaterally in her lower limbs. On examination, power was 3/5 in both lower limbs and 5/5 in her upper limbs. Tone was normal, sensation and reflexes were intact without evidence of coordination deficits and an extensor plantar reflex. A repeat MRI Brain and whole spine with contrast was negative for leptomeningeal or parenchymal enhancement. Without a diagnosis and progressive neurological deficits, a broader differential was conducted to include nerve conduction studies, a repeat autoimmune, vasculitic and viral screen, CT thorax, abdomen & pelvis, and serum ACE all of which were non-diagnostic. Finally, a repeat LP with CSF immunophenotyping and second MRI whole spine with contrast were ordered to exclude infiltrative disease (Figure 1). This MRI result was discussed at three major neuroradiology sites in our country to form a consensus on the presence of infiltrative disease. Subtle posterior meningeal enhancement involving the distal cord at T10 and T11 vertebral bodies was observed. In the context of macroglobulinaemia, a bone marrow biopsy was performed which showed a normocellular specimen with no evidence of lymphomatous infiltration. While awaiting her CSF sample to return from flow cytometry she deteriorated with ascending paralysis compromising respiratory drive and requiring transfer to the intensive care unit (ICU). The following morning, CSF immunphenotyping revealed a clonal population of kappa light chains restricted B cells, which were CD5 and CD10 negative, consistent with CNS involvement by lymphoma, in keeping with a diagnosis of BNS.