Studies of upper limb pain in occupational medicine, in general practice, and among computer operators .

Diagnostic consensus criteria cannot be applied in a major proportion of patients with upper limb complaints, many of which are regarded as "non-specific". The three empirical studies in this thesis aimed to address this diagnostic challenge by incorporating representative neurological qualities in the physical examination.
Patterns of muscle weakness, sensory abnormalities and nerve trunk allodynia based on the nerves' topography and their motor and cutaneous innervation were defined to reflect peripheral nerve afflictions and their locations. The physical examination was first validated on patients in clinical occupational medicine. Next, the neurological patterns were studied among computer operators in order to contribute to the characterization of their disorder. Finally, self-reported work-exposures for patients in general practice presenting with symptoms and findings consistent with brachial plexopathy were compared with the exposures of matched control patients without upper limb symptoms.
The inter-rater reliability of manual individual muscle testing, and of assessments of sensibility (touch, pinprick and vibration) and mechanosensitivity of nerve trunks was generally moderate to good. Patterns of findings in accordance with neuropathy at ten locations were identified with moderate to good reliability. The identified patterns reflected the presence of symptoms with high positive and negative predictive values. An examination limited to the assessment of strength in six muscles was shown to be sensitive but non-specific.
Computer operators with severe upper limb complaints are characterized by rather uniform physical findings in accordance with an infraclavicular brachial plexopathy in combination with median and posterior interosseous neuropathy at elbow level. In spite of reduced symptoms at follow-up, the prognosis in terms of work-status and persisting pain is serious. A cross-sectional study of computer operators in current work showed that individual and patterns of neurological findings in symptomatic subjects reflected these three locations of focal neuropathy. Pain was common in the studied sample, but of low intensity. Physical abnormalities were frequent and related to summarized pain. Patterns in accordance with brachial plexopathy, and median (elbow) and posterior interosseous neuropathies were identified in a minor proportion of limbs, in particular in the mouse-operating limb. A stretching course designed to improve the mobility and available space for the nerves at the three locations reduced the pain level but did not influence physical findings at follow-up. The relation of symptoms to the identified neurological patterns and the effect of stretching provide additional support to the construct validity of the applied neurological examination. This study indicates the role of nerve afflictions in computer-related upper limb disorders.
The most frequent pattern in the first two studies was in accordance with brachial plexopathy. Therefore additional analyses addressed the relation of this condition to me-chanical exposures at work. Whether assessed as the extent during the workday or days per week, many exposures, in particular adverse upper limb postures, repetitive work, work pace, and the use of force, were significant risk indicators for brachial plexopathy with clear dose-response relationships.
The identification of patterns of physical findings that reflect the function of the peripheral nerves appears to be a rewarding diagnostic procedure in subjects with upper limb symptoms. The relation of patterns to symptoms indicates the diagnostic feasibility of the examination and can contribute to explain symptoms in workers such as computer operators. Patterns in accordance with brachial plexopathy are frequent and related to mechanical work-exposures.