An n-of-one RCT for intravenous immunoglobulin G for inflammation in hereditary neuropathy with liability to pressure palsy (HNPP)

Hereditary neuropathy with liability to pressure palsy (HNPP; tomaculous neuropathy) is a rare autosomal dominant disorder caused by a loss of function of the peripheral myelin protein 22 gene ( PMP22 ; OMIM #601097) for which no curative treatment exists. Symptoms consist of recurrent painless episodes of focal sensory loss and muscle weakness, which are often provoked by nerve compression and resolve spontaneously within days to months.1 In this report, we describe the case of a female patient with HNPP who initially presented with symptoms of a painful neuropathy which were successfully treated with intravenous immunoglobulin G (IVIg), and the results of a double-blind, placebo-controlled n-of-one trial to assess the effectiveness of IVIg in this patient. In 2002, a 35-year-old female patient presented with a 15-month history of neuropathic pain in the right leg, and recurring episodes of weakness and sensory loss in the legs which resolved spontaneously after several weeks. Her medical and family history was unremarkable. Physical examination showed mild proximal weakness of the left leg (Medical Research Council (MRC) grade 4), severe weakness of the left foot extensors (MRC 0–2), hypoalgesia of the left hand and lower leg, and reduced tendon reflexes with absent Achilles reflexes. All additional investigations were normal, except electromyographic (EMG) studies which showed bilateral demyelinating conduction blocks at ulnar nerve compression sites, prolonged distal motor latencies of the ulnar, tibial, peroneal and median nerves, and absent F-waves in peroneal and right tibial nerves, …