Exercise-Induced Weakness of the Leg Muscles - Cycling

Abstract

HISTORY: A 40 year old hobby cyclist (annual training volume 10,000 km, regular participation in cycling marathons) with a history of weakness, numbness and “pins/needles” sensation of both lateral buttocks, thighs, calves and feet over the past two years. The discomfort occurred during cycling, especially uphill and most recently when walking quickly after at least 200 meters. The discomfort disappeared immediately at rest. Due to the discomfort he had to substantially reduce cycling-training. PHYSICAL EXAMINATION: 40 year old healthy, in good general health, the examination of the heart and the lungs produced no pathological findings, blood pressure was normal, and a supraumbilical systolic murmur could be heard at the abdomen. Examination of the pulses revealed a weak but symmetrical finding in both legs and feet. No muscular atrophy, no paresis and no loss of sensation. The reflexes were normal. Examination of cranial nerve status revealed no pathological findings. DIFFERENTIAL DIAGNOSIS: Central or peripheral neurological disease Myopathy Disease of the spinal column Vascular disease TEST AND RESULTS: Before admission to our clinic, preceding neurological examination including electroneurography, EMG and MR tomography of the spinal column revealed only a mild prolapsed intervertebral disc L¾ und L4/5. Exercise testing: Continuous walking at 6 km/h induced pain in both legs after 1 min. Calf muscle (CF) oxygenation as measured by Near-infrared spectroscopy (NIRS) showed a persistent decrease of StO2 from 60 to 27 %. Ultrasound of the abdomen: 10x7 mm large flap valve structure at the infrarenal abdominal aorta with luminal constriction and pronounced turbulent flow in the duplex scan. The Doppler scan revealed an acceleration of the flow to more than 6 m/sec in the stenosis. Angiography: High grade short focal stenosis of the infrarenal aorta with collateral circulation through lumbal arteries and the A. mesenterica inferior. FINAL WORKING DIAGNOSIS: Peripheral arterial occlusive disease stage IIb, due to the high grade short focal stenosis of the infrarenal aorta. TREATMENT AND OUTCOMES: Angioplasty and stenting with a self-expanding Nitinol Stent Secondary prophylaxis: Platelet aggregation inhibitor, statin therapy, advice to quit smoking, continue the aerobic exercise. The patient returned to cycling, starting with basic endurance training. No recurrence of prior symptoms and return to a good physical performance. Using the walking protocol as mentioned above, oxygenation kinetics (NIRS) in CF normalized with an initial smaller decrease in StO2 from 62 to 52%, followed by an increase to 72% until the end of exercise.