Page 374 - Medicine and Surgery

P1: KTX
BLUK007-08 BLUK007-Kendall May 12, 2005 19:48 Char Count= 0

370 Chapter 8: Musculoskeletal system

may be oral ulcers, dental caries and firm non-tender age of 40 years. The inflammation within muscle causes
enlargement of the parotid gland. necrosis and patchy regeneration with fibrosis and atro-
Other manifestations include arthralgia, Raynaud’s phy in later stages. The skin shows collagenous thicken-

phenomenon and an association with other organ ing of the dermis with chronic inflammatory cell infil-
specific autoimmune disorders in primary Sj¨ ogren’s trates.
syndrome, e.g. thyroid disease. Occasionally there are
systemic features including vasculitis and renal tubu- Clinical features
lar defects. Gradual onset of non-specific systemic features followed
by symmetrical, progressive, proximal muscle weakness.
Investigations In more chronic presentations there is muscle atrophy,
Anaemia of chronic disease, leucopenia and high ESR contractures and calcinosis. Skin manifestations include

Rheumatoidfactor(RhF)ispositivein80–100%,ANA a purple rash on the eyelids often with oedema (he-

positive in 60–80%, anti-Ro (SSa) antibodies are seen liotrope rash) and scaly vasculitic patches on the knuck-
in primary Sj¨ ogren’s syndrome and may cause neona- les(Gottron’spapules).Theremaybeskinulcerationand
tal heart block in offspring of affected women. Raynaud’s phenomenon. Occasionally there is cardiac
Schirmer’s test for keratoconjunctivitis sicca measures involvement leading to heart failure, respiratory involve-

tear production. An edge of a strip of filter paper is ment, including nonspecific interstitial pneumonia, and
placed in the lower eyelid and the length that becomes oesophageal involvement, which may be sufficiently se-
wetis measured. vere so as to require gastrostomy feeding.

Management Investigations
Artificial tears and saliva replacement solutions provide Inflammatory markers: The ESR is raised.
symptomatic relief. Autoantibodies: Anti-histidyl-tRNA synthetase (anti-
Jo1) are seen in 30%, and rheumatoid factor is positive
Polymyositis and dermatomyositis in 30%.
CK-MB fraction and troponin I can be used to assess
Definition cardiac involvement.
Myositis is an inflammatory disorder of striated muscle. Raised muscle enzymes such as creatine kinase (prior
When associated with skin manifestations it is termed to biopsy).
dermatomyositis. EMG:Spontaneousfibrillationsatrest,abnormallow-
amplitude, short-duration polyphasic motor poten-
Prevalence tialsonvoluntarycontractionandhigh-frequencydis-
1per 100,000 population. charges.
Muscle biopsy is definitive.

Age MRI of thighs is routinely performed.
Any, peaks 40–50 years.
Management
Sex Acute phases are treated with corticosteroids, which
2F: 1M should be reduced gradually to a low-maintenance dose.
Methotrexate, azathioprine or cyclophosphamide are
Aetiology/pathophysiology used in resistant cases.
Lymphocytic infiltration, autoantibody production and
HLA-DR3 association suggests an immune-mediated Prognosis
pathogenesis. There may be environmental trigger The condition may last several years. The disease is
factors. Dermatomyositis is associated with malignancy of variable severity, and spontaneous remissions can
(e.g. lung, stomach carcinoma) predominantly over the occur.