1653 - Cloud Interference Analysis for Diagnosis of Neuropathic versus Myopathic Disorders: A Literature Review

Objectives: Both visual assessment of the motor unit potential (VMUP) and quantitative assessment of motor unit potential (QMUP) are used to discriminate between neuromuscular disorders during electromyography. However, neither method is highly accurate and both invite subjectivity. Interference pattern analysis (IPA) is another electrodiagnostic method used to analyze myopathic versus neuropathic disease. Automatic Interference Pattern Analysis (aIPA), also known as cloud analysis, is a computational method which utilizes objective properties of EMG data to output a cloud analysis which can visualize and discriminate between neuropathic and myopathic disease. This review evaluates literature describing clinical utility of aIPA.

Design: A literature review was performed via a PubMed search with key search terms including “electromyographic interference pattern”, “automatic analysis”, “interference pattern”, “cloud analysis”, and “neuropathic AND myopathic”, either individually or in combination.

Results: A total of 39 articles on EMG models used to differentiate between neuropathic and myopathic diseases were reviewed, of which 10 focused on aIPA. aIPA consists of three cloud analysis methods which measure the log activity between turns and amplitude, number of small segments and activity, and envelope activity. Analysis of the cloud analysis patterns in combination yields the greatest accuracy in identifying neuromuscular disease as compared to VMUP and QMUP. Three of the articles refer to this process as cloud analysis, four as aIPA, and three as interference patterns. Four articles focused on sensitivity/specificity evaluation and four articles described establishing normative cutoffs.

Conclusions: Overall, literature on aIPA is limited, despite it being a method widely available on commercial electromyographic devices. Studies are published using variant nomenclature to describe the method and no standard term has been accepted. Within the available literature, aIPA demonstrates superiority in sensitivity and specificity over VMUP and QMUP in differentiating between neuropathic, myopathic, and normal muscles. The diagnostic accuracy and objectivity suggest a benefit from expanded clinical use.