A clinical study on the utility of muscle biopsy in patients with suspected myopathy
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Date
2019-12
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SCTIMST
Abstract
Myopathy is one of the common disorders in patients attending neuromuscular clinic.
Systematic approach comprising a comprehensive clinical history, thorough neurological and
systemic examination, nerve conduction studies, EMG and relevant biochemical tests should
be undertaken in all cases. Muscle biopsy is one of the most frequently used diagnostic
procedures in the evaluation of inherited and acquired myopathies. The yield of muscle biopsy
result is dependent on number of factors, including appropriate selection of patients for biopsy,
expertise of the laboratory, and techniques used in the analysis.
The history of muscle biopsy dates back to 1860 when Duchenne first performed a biopsy on
a patient with symptoms of myopathy. Introduction of enzyme histochemical methods by
Victor Dubowitz in 1970 revolutionised the role of muscle biopsy in the diagnosis of various
primary and secondary muscle diseases(7). Diagnosis of various subtypes of dystrophies was
further made easy with beginning of immunohistochemical methods in 1980s However, there
are few modern reports documenting the diagnostic yield and clinical utility of open muscle
biopsy.(1-5) Clinicians usually rely on personal experience to develop their own criteria for
performing muscle biopsy. This may explain the variable diagnostic outcome of muscle biopsy
found in previous cohorts which ranged from 13.2% to 59.9%.(8,9).
In most of the proximal myopathies and generalised/systemic diseases; vastus lateralis is the
standard muscle biopsied by international consensus. (6) The other muscles that are good
choices for biopsy are biceps and gastrocnemius. However, many forms of hereditary muscle
disorders can now be diagnosed with molecular genetic testing, thereby eliminating the need
for performing a muscle biopsy in every patient.
In this study, we evaluate the clinical utility of muscle biopsy in patients with suspected
myopathy. The primary objective is to determine the diagnostic value of muscle biopsy, as
measured by the probability of specific myopathy and depending on the available pre procedure clinical and laboratory data