SHOULDER PAIN DIFFERENTIAL DIAGNOSIS

weakness and/or decreased motor reflexes (if a motor nerve is involved). The pain is described as sharp and travels along a very narrow pathway, often identified by the patient with a single finger, however the pain distribution can be similar to that of somatic pain referral patterns, so differentiation is difficult. Due to the anatomy of the cervical spine, radiculopathy cannot occur at multiple levels, and if identified urgent referral needs to be arranged.

Visceral Many visceral diseases are well known

GENERALLY HAVE A LOWERED IRRITABILITY THRESHOLD

to present as unilateral shoulder pain, this is usually due to disease of the autonomic nervous system (Table 1 and 2). This pain is not well localised but generally within the segmental innervation of the affected organ. Shoulder pain associated with any of the following should be taken as an indication of visceral illness, even

TABLE 1: SHOULDER PAIN OF VISCERAL ORIGIN (ADAPTED FROM ZOHN DA (8)) RIGHT SHOULDER Location

LEFT SHOULDER

Systemic origin Peptic ulcer

Myocardial ischemia Acute cholecystitis

Liver abscess Gallbladder Liver disease

Pulmonary Pleurisy Kidney

Lateral border right scapula Right shoulder, down arm

Right shoulder, between scapulae (right subscapular area)

Right shoulder Right upper trapezius

Right shoulder, right subscapula Right shoulder Upper trapezius Right shoulder

Systemic origin Ruptured spleen

Myocardial ischemia

Ectopic pregnancy (ruptured) Pancreas

Location Left shoulder

Myocardial ischemia Left shoulder

Left shoulder

MUSCLES WHICH ARE PRONE TO TIGHTNESS

if the shoulder pain is exacerbated by movements; persistent cough, blood speckled sputum, deep inspiration, coughing, laughing, chest pain, exacerbation by laying down, nausea, vomiting, jaundice or urological complaints amongst others (3).

Muscular Recent developments in the management of chronic pain have identified localised areas of soft tissue dysfunction (trigger points), which produce pain in both local and distant structures (4). According to Melzack and Wall (4), 80% of these trigger points lay at the same sites as traditional Chinese acupuncture points.

Pulmonary Pleurisy Kidney

Left shoulder Upper trapezius Left shoulder

TABLE 2: SYSTEMIC CAUSES OF SHOULDER PAIN (ADAPTED FROM ZOHN DA (8))

Neck Bone tumors

Metastases

Nodes in neck (from leukaemia, and Hodgkin’s disease)

Cervical cord tumors

Chest Angina/myocardial infarct

Pericarditis Aortic aneurysm

Empyema and lung abscess

Pulmonary TB Pancoast’s tumor

Lung cancer (bronchiogenic carcinoma)

Spontaneous pneumothorax

Nodes in mediastinum/ axilla

Thoracic spine metastases Breast disease

Primary/secondary cancer Mastonia Hiatal hernia

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Abdomen Liver disease

Ruptured spleen Spinal metastases

Dissecting aortic aneurysm

Diaphragmatic irritation Peptic ulcer Gallbladder disease

Subphrenic abscess Hiatal hernia Pyelonephritis

Diaphragmatic hernia Ectopic pregnancy rupture

Upper urinary tract Systemic disease

Collagen vascular disease Gout Syphilis/gonorrhea

Sickle cell anaemia

Haemophilia Rheumatic disease Metastatic cancer

Breast Prostate Kidney Lung

Thyroid Testicle

Trigger points A trigger point is defined as an exquisitely tender spot in an indiscreet taught band of hardened muscle which produces symptoms (5). Causative factors of trigger points include: n Constant muscular contraction n Overuse n Emotional stress n Localized trauma n Sub-optimal local environment such as heat, cold, damp n Prolonged muscle inactivity n Hormonal imbalances n Nutritional imbalances n Compensation within antagonist for agonist n Visceral disease

Trigger points can be sub-divided into “active” or “latent” according to the patient’s appreciation of the pattern of referred pain. If a trigger point is stimulated and produces a characteristic pattern of pain referral then it is classified as “active”. Painful points which do not refer symptoms distally are termed “latent”. The way in which trigger points refer pain to distal sights is thought to involve the brain “mislocating” the pain messages it receives (6).

There are many muscles around the upper quadrant which can cause referred pain to the area of the glenohumeral joint, due to the presence of active trigger points (see table 3). These can be distinguished by active palpation of the muscle, which may (in the presence of an active trigger point) reproduce or heighten the patient’s distal pain response, or illicit pain within the muscle’s characteristically tight

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