Axonal sensorimotor neuropathy in patients with [beta]-thalassaemia

Thalassaemia comprises a heterogeneous group of hereditary disorders characterised by a decrease in the production of one or more globin chains. Multiple complications can result from chronic anaemia on one hand to transfusion related haemosiderosis on the other. The peripheral nervous system, however, is rarely affected. Myopathic syndromes ^{1- 3} and peripheral neuropathy have been reported. ^{4- 6} Desferrioxamine (DFO), used as chelation therapy to reduce transfusion induced iron overload, can cause ophthalmological disorders and high frequency sensorineural hearing loss. ^{7- 9} Sensorimotor neurotoxicity, associated with high dose DFO treatment has also been reported. ¹⁰

In this study we evaluated patients with [beta]-thalassaemia clinically and electrophysiologically, and investigated whether factors such as age, clinical severity of thalassaemia (homozygous [beta] or intermedia), antibodies against hepatitis C virus (HCV), ferritin levels, haematocrit (Ht), and history of transfusions, splenectomy, or DFO treatment are associated with abnormal findings.

PATIENTS AND METHODS

We examined a consecutive series of 36 patients with thalassaemia (19 women, 17 men; mean age 29.2+-8.2 years, range 16-58) followed up at two tertiary referral centres. Patients with diabetes or other known possible causes of neuropathy were excluded from the study. Thirty two had homozygous [beta]-thalassaemia and four [beta]-thalassaemia intermedia. All patients had normal vitamin B₁₂ , folic acid, and serum protein electrophoresis and immunofixation. No patient had clinical evidence of visual or auditory dysfunction. The control group consisted of 17 healthy individuals (12 women, 5 men; mean age 27.6+-9.1 years, range 16-55).

In all patients the electrophysiological studies were performed by the same investigator. Standard procedures were used. Motor nerve conduction studies (NCS) of the right ulnar and peroneal nerves were performed. Surface electrode recordings were obtained from the abductor digiti minimi and the extensor digitorum brevis. Antidromic sensory nerve conduction studies of the right ulnar and sural nerves were performed. Measurements were taken at temperatures of 32 °C and 29 °C for the upper and lower limbs, respectively. Deviations of 2 standard deviations (SD) or more relative to the mean values of the controls were considered abnormal.

The neuropathy was assessed clinically by the neuropathy symptoms score (NSS) and the neuropathy disability score (NDS). ¹¹ Serum ferritin levels were assessed at the same time. The haematocrit used in the statistical analysis was the...