A 71-year-old woman presented with a 2-year history of progressive, painless numbness of hands and feet. Medical history was significant for breast cancer 17 years previously with no recurrence after mastectomy as the sole treatment, bronchiectasis and of episodes of herpes zoster in the right leg. Her initial symptoms were numbness affecting the feet with gradual spread to mid-calf and gait unsteadiness. Later, numbness of hands and forearms developed associated with difficulty in writing, weakness of hands and lower extremities followed by inability to climb stairs.
Physical examination was normal except for diminution of touch and pain sensation in the hands and to the level of mid-calves, and severe impairment of vibration and position senses in the legs. There was distal weakness of upper extremities and wasting of small muscles of the hands and all muscle groups of legs were slightly weak with hyporeflexia throughout.
Laboratory investigation disclosed normal hematology, elevated ESR of 40, elevated protein in CSF to 0.88 g/l (nl:0.2-0.4), and a monoclonal increase in serum IgM (kappa) to 17.8 g/l (nl:0.6-2.8). Nerve conduction studies demonstrated a 70% decrease in conduction velocities throughout. Thirty percent of the cells in bone marrow biopsy had mature lympho-plasmacytic features (Fig 1). A sural nerve biopsy was performed.