Chronic Acquired Demyelinating Polyneuropathy following Renal Transplantation

The clinical, laboratory, and treatment findings of a patient with chronic acquired demyelinating polyneuropathy (CADP) in association with renal transplantation are described. Like the present case, many such patients have been described under the rubric of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). 1. Introduction The chronic acquired demyelinating polyneuropathies (CADP) are treatable heterogeneous disorders. Electrodiagnosis, which distinguishes primary demyelination from primary axonal neuropathy, achieves 95% sensitivity in CIDP [1]. Numerous conditions have been associated with CADP, among them solid organ transplantation [2]. Only ten heterogeneous patients [3] with preexisting axonal polyneuropathy met definite demyelinating electrodiagnostic criteria after solid organ transplantation [2]. We present the detailed clinical findings of another patient with progressive demyelinating neuropathy suggested by serial electrodiagnostic studies, diagnostic features on cutaneous nerve biopsy, and a positive response to intravenous immune globulin (IVIg), a preliminary report of which has been published [4]. 2. Patient Report A previously healthy 74-year-old man with solitary kidney developed renal insufficiency in 2008 prompting hemodialysis and eventual donor transplantation in 2009. Afterward, he was maintained on tacrolimus. This was followed shortly afterward by glycemic intolerance managed with diet. In 2011, he noted numbness, tingling sensation, and gait instability. Neurological examination showed tandem gait imbalance and symmetrical stocking vibratory and cold temperature sensory loss to below the knees, with slight weakness of the tibialis anterior muscles versus firm resistance that was graded Medical Research Council (MRC) 4/5 bilaterally. There was generalized hyporeflexia with intact limb strength, cognition, and cranial nerve function. Electrodiagnostic studies (Table 1) showed low amplitude compound muscle action potentials (CMAP), slow motor nerve conduction velocities, prolonged distal motor latencies, prolonged or absent F wave latencies, and abnormal temporal dispersion without active or chronic spontaneous activity at rest on concentric needle electromyography (EMG). Epidermal nerve fiber (ENF) studies of the left calf and thigh showed significantly low ENF density: distal leg 0.06 and thigh 5.4？ENF/mm (5th percentile reference values, resp., 5.0 and 8.0？ENF/mm 9) without histologic abnormalities or amyloid deposition. The serum creatine kinase was 172？U/L (normal < 150). Left sural nerve biopsy showed chronic