INTRODUCTION: Chloroquine is a drug that is widely used in rheumatology and 
occasionally prescribed in dermatology. From a neurotoxicological point of view, 
chloroquine can have effects on the peripheral nerves, muscles, neuromuscular 
junctions and the central nervous system. In this study we analyse the clinical, 
neurophysiological and anatomopathological findings in two patients with 
chloroquine induced neuromyopathy, which took the form of a 
polyradiculoneuropathy.
CASE REPORTS: Case 1: a 75 year old female with rheumatoid arthritis treated 
with daily doses of 250 mg of chloroquine for four years. The patient visited 
because of several months history of predominantly proximal progressive 
tetraparesis with areflexia. Analytical tests and lumbar puncture were normal. 
Electromyogram (EMG): proximal myopathic and distal neuropathic patterns. 
Muscular biopsy: vacuolar myopathy with accumulations of phagolysosomes, lipids, 
lipofuscin, myelinic curvilinear bodies. Case 2: a 74 year old female with 
arthropathy treated with daily doses of 250 mg of chloroquine for nine months. 
The patient presented a progressive proximal paraparesis with generalised 
areflexia. Analytical tests and lumbar puncture were normal. EMG: mixed sensory 
motor polyneuropathy, myogenic pattern with high frequency discharges in the 
iliac psoas and a neurogenic pattern in the distal muscles. Muscular biopsy: 
vacuolar myopathy suggesting a myopathy due to chloroquine. After stopping 
treatment with this drug the patients progressed favourably.
CONCLUSION: Chloroquine can induce a clinical pattern that suggests a 
polyradiculoneuropathy. It is important to establish a history of having taken 
this drug. If this is indeed the case, then an electromyographic study of the 
most proximal muscles should be performed in order to detect a myogenic pattern 
and the same exploration should be applied to the distal muscles to reveal a 
neurogenic pattern. The final diagnosis will be established by muscular biopsy.