Treating Muscular Dysfunction of Upper Limbs
Muscular dysfunction of the upper limb muscles—from an array of etiologies—is associated with pain.1 Those etiologies can be classified in several categories: neural, vascular, osteo-capsular, myofascial, muscular, traumatic (including repetitive motion and chronic fatigue), endocrine, psychosomatic or somatoform, immuno-deficient (including autoimmune), or mixed. The categories listed above are not exhaustive, but they encompass the most frequent conditions that a clinical pain practitioner may need to rule out. In addition, one may have to consider whether the pain pattern is derived from the structures of the upper limb or may be secondary to a referred pattern from the viscera, including anginal type of pain.
The discussion below will refer mainly to musculo-skeletal dysfunction pain and other symptoms related mainly to myofascitis and other related traumatic etiologies.
Pain in muscles is usually associated with abnormal electric patterns. In terms of the upper limb muscular dysfunction, there is frequently a history of repetitive motion followed sequentially by lack of adequate rest, fatigue, and pain. SEMG testing has helped to clarify a number of functional clinical observations in regards to the fatigue-pain continuum often associated with repetitive motion injury.
Repetitive motion injury of muscles of the upper limb is a historical phenomenon. It is interesting to note the evolution of such injuries in the industrial era from primary shoulder injuries to elbow injuries and the recent epidemic of wrist injuries with the advent of work with the keyboard.
Acute upper limb pain usually lasts less than 6-12 weeks. Sub-acute pain and recurrent pain may last beyond 12 weeks. Chronic pain is usually the result of delayed or unresolved healing and may last for several months or years, until the underlying condition is resolved. Chronic upper limb muscular or myofascial pain may lead in time to hyperalgesia and allodynia.1,2,3 Phantom limb pain is a neural phenomenon more commonly associated with traumatic amputation of the limb or parts thereof.
Effects of Trauma
In the case of trauma to one limb, that limb tends to undergo a ‘guarded’ or ‘splinted’ posture for several days or weeks. Commonly, the contra-lateral limb will offer ‘protective guarding’ for as long as necessary. The upper limb has distinct joint functions but functions also as a ballistic or postural myotatic vector, with all the muscles subtending the same action at one given time. It is comprised of four myotatic units: shoulder, elbow, wrist and hand. A number of muscles participate in more than one primary joint unit because of their anatomy. Brachioradialis is a case in point.
Unless the healing of the injured upper limb occurs within a very short period of time, one result may be the loss of strength of the myofascial unit or vector involved.
The overall conditioning level of the entire injured myotatic unit or vector will decrease over time, even over the space of a few weeks. The suffering muscle may become shortened and the adjoining muscles from the unit may start functioning at a suboptimal length. The affected joint may have to function at a reduced range of motion (ROM).4 The protective guarding activity involves not only the contra-lateral limb but also the muscles of the proximal and distal joints of the affected limb.
Over time, the functional changes, including the loss of strength (LOS) and the joint/ capsule range of motion (ROM) may contribute to the change in the spread of the neuromuscular cortical engram.5 Chronic muscular dysfunction and its pain harbinger may be associated with deleterious (negative, pathologic) neuroplastic changes until healing occurs.6
Evaluation and Diagnosis
The rehabilitation process of dysfunctional upper limb muscles needs to take into consideration a number of factors. These include, but are not exclusive to, the following: the diagnosis, current treatments, age, overall state of muscular conditioning, motivation to improve the overall muscular function to reduce pain, emotional make-up and emotional state, concurrent psycho-social, and familial change of roles related to the muscular dysfunction, and concurrent conditions.7
The evaluation of the muscular dysfunction and pain of the upper limb is done within the framework of a comprehensive physical examination.7 The next step involves the performance of objective assessments such as dynamometry for the measurement of the muscular strength and loss of strength (LOS). The ROM of the upper limb joints, i.e., the shoulder, elbow, wrist and hand is best measured with inclinometry according to established methods.4 Joint/ muscular proprioception needs to be assessed by semi-quantitative means, in comparison to the contra-lateral limb. The pain intensity may be assessed on a visual analogue scale, in a semi-quantitative fashion.8
The electrical potential changes associated with upper limb dysfunction, such as (electric potentials) spasm, hypertonus, hypotonus, co-contraction, co-activation, difficulty with control or achievement of the resting tonus, myokimia, fasciculations, loss of mirror image of segmental motions, utilization of increased numbers of contractile elements, fatigue (as evaluated by the use of the spectral analysis, median frequency), etc. can be achieved via the utilization of well documented dynamic protocols of surface electromyography (SEMG).9
“In general, the electric potentials pattern during movement through a classic joint ROM is such that more energy is expended by a dysfunctional muscle during any given motion, even if executed at the minimal level of effort.”
This electrophysiological modality has a dual application: (1) the investigation of the muscular dysfunction through motion and rest during the classic or functional upper limb ROM, and (2) the muscular re-education of the resting tonus and activity tonus of the dysfunctional muscles.
Both applications can be achieved by utilizing well established protocols, within the framework of the clinical presentation.7
This modality is rather unique in terms of the rehabilitation component: it is active. The healing process noticed peripherally on the upper limb muscles is related to the re-establishment of the neuro-motor engram and the positive neuroplastic process.
The availability of a database of the SEMG of the upper limb ROM of over 1,000 asymptomatic muscles, completed by the author, allows for a more focused and objective diagnostic and rehabilitative process.9,10 In addition to the SEMG amplitude potentials data of asymptomatic upper limb muscles, the author has compiled a similar data set for symptomatic upper limb muscles.10,11