Plexopathy „turning into“ contralateral multiplex polyneuropathy in a patient with chronic CSF inflammation and monoclonal gammopathy

Introduction: Immunologically mediated PNP displays a variety of heterogeneous and dynamic patterns that are often diagnostically challenging.

Case: A 70-year-old well-adjusted diabetic patient presented with lower back pain and painful weakness of hip flexion and adduction on the left. EMG/ENG showed acute signs of denervation in the M. rectus femoris and M.adductor magnus as well as in the paravertebral muscels of nerve roots L2, L3 and L5 on the left. MRI showed inflammatory signal abnormalities of the left lumbosacral plexus. A compressive / infiltrative tumour or paraneoplastic disorder was was not found. The condition was interpreted as diabetic asymmetric polyneuropathy with radicular involvement and further diabetic treatment enhancement recommended. One and a half year later, the same patient had almost completely recovered from the symptoms in the left thigh, but had instead developed weakness of hip flexion and thumb function on the right. EMG/ENG showed signs of a predominantly motor, but also sensory, axonal asymmetric neuropathy, i.e. signs of regeneration in the left M.rectus femoris but acute signs of denervation in the right M.rectus femoris as well as in the M. interosseus dorsalis I and M. abductor pollicis on the right. This time, CSF anlaysis revealed signs of chronic inflammation and serum analysis a monoclonal gammopathy.

Methods: EMG/ENG, MRI, CSF analysis, laboratory tests, nerve biopsy

Conclusions: We propose an unusual course of immunologically mediated PNP, potentially linked to the gammopathy and/or the diabetes. The diagnostic material will be fully displayed and the differential diagnosis be discussed with regard to the current literature.