Upper extremity nerve involvement in Swedish female machine milkers

• Published in: American journal of industrial medicine Vol. 33; no. 6; pp. 551 - 559
• Main Authors: Stål, Marianne, Hagert, Carl-Göran, Moritz, Ulrich
• Format: Journal Article
• Language: English
• Published: New York Wiley Subscription Services, Inc., A Wiley Company 01-06-1998; Wiley-Liss
• Subjects: Adult; Agricultural Workers' Diseases - epidemiology; Agricultural Workers' Diseases - etiology; Agricultural Workers' Diseases - surgery; Biological and medical sciences; Cranial nerves. Spinal roots. Peripheral nerves. Autonomic nervous system. Gustation. Olfaction; Dairying - instrumentation; Female; Follow-Up Studies; Forearm - innervation; Forearm - surgery; Humans; Male; median entrapment; Median Nerve - surgery; Medical sciences; Middle Aged; milker; Nerve Compression Syndromes - epidemiology; Nerve Compression Syndromes - etiology; Nerve Compression Syndromes - surgery; Nervous system (semeiology, syndromes); Neurologic Examination; Neurology; occupational injury; Pronation; pronator syndrome; Syndrome; Weight-Bearing - physiology; Sweden; Europe; Human; Nervous system diseases; Compression; Diseases of the osteoarticular system; Occupational exposure; Trauma; Median nerve; Milking; Female; Upper limb; Diagnosis; Peripheral nerve disease; Occupational medicine
• ISSN: 0271-3586; 1097-0274
• DOI: 10.1002/(SICI)1097-0274(199806)33:6<551::AID-AJIM5>3.0.CO;2-T

Entrapment of the median nerve in the proximal forearm, the so‐called pronator syndrome, is considered a rather rare condition but it is four times more common in women than in men. In this study, 23 of 30 female machine milkers with symptoms in the forearm and hand were clinically diagnosed as having the pronator syndrome. The diagnosis of median nerve involvement was based on the clinical history and on physical examination by a hand surgeon. All 23 milkers complained of aching in the volar part of the forearm and had a sensation of numbness, tingling, and decreased muscle strength in their hands, mostly in the hands which usually were statically loaded with heavy equipment. Objectively, all had an experience of tenderness over the pronator teres muscle. Furthermore, they showed reduced muscle strength, especially in the following muscles: pronator teres (PT), flexor carpi radialis (FCR), flexor pollicis longus (FPL), and flexor digitorum profundus II (FDP II).
To validate the manual muscle testing, Mannerfeldt's intrinsicmeter was used to quantify the clinically observed weakness.
Eight of the 23 milkers with pronator syndrome were surgically released from neuropathy and were almost symptom‐free at follow‐up after six months. One patient had a slight sensation of numbness and had to be given surgical carpal tunnel release later on. The external exposure of the arm during the application of the milking cluster probably causes muscle and fascial tensions that induce compression of the nerve. Further studies are needed to establish the level of the internal exposure. Am. J. Ind. Med. 33:551–559, 1998. © 1998 Wiley‐Liss, Inc.