A Pattern Recognition Approach to Patients with a Suspected Myopathy - 17/07/14

Doi : 10.1016/j.ncl.2014.04.008

Richard J. Barohn, MD ^a,^⁎ , Mazen M. Dimachkie, MD ^b, Carlayne E. Jackson, MD ^c
^a Department of Neurology, University of Kansas Medical Center, 3901 Rainbow Boulevard, Mail Stop 2012, Kansas City, KS 66160, USA
^b Neuromuscular Section, Neurophysiology Division, Department of Neurology, University of Kansas Medical Center, 3901 Rainbow Boulevard, Mail Stop 2012, Kansas City, KS 66160, USA
^c Division of Neurology, UT Medicine San Antonio, University of Texas Health Science Center, 8300 Floyd Curl Drive, Mail Code 7883, San Antonio, TX 78229-3900, USA

^∗Corresponding author.

Résumé

Myopathies are a heterogeneous group of disorders that can be challenging to diagnose. This review provides a diagnostic approach based predominantly on the clinical history and neurologic examination. Laboratory testing that can be used to confirm the suspected diagnosis based on this pattern recognition approach is also discussed. Careful consideration of the distribution of muscle weakness and attention to common patterns of involvement in the context of other aspects of the neurologic examination and laboratory evaluation should assist the clinician in making a timely and accurate diagnosis and can sometimes minimize the expense of further testing.

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Keywords : Myopathy, Limb-girdle, Distal myopathy, Inflammatory myopathy, Metabolic myopathy, Myotonia

Plan

Key points

Introduction

Clinical evaluation

Which Negative and/or Positive Symptoms Do Patients Demonstrate?

What is the Temporal Evolution?

Is There a Family History of a Myopathic Disorder?

Are There Precipitating Factors That Trigger Episodic Weakness or Stiffness?

Are There Associated Systemic Symptoms or Signs?

What is the Distribution of Weakness?

Pattern recognition approach to myopathic disorders

Pattern 1: Proximal Limb-Girdle Weakness

Pattern 2: Distal Weakness

Pattern 3: Proximal Arm/Distal Leg Weakness (Scapuloperoneal)

Pattern 4: Distal Arm/Proximal Leg Weakness

Pattern 5: Ptosis with or Without Ophthalmoparesis

Pattern 6: Prominent Neck Extensor Weakness

Pattern 7: Bulbar Weakness

Pattern 8: Episodic Pain, Weakness, and Myoglobinuria

Pattern 9: Episodic Weakness Delayed or Unrelated to Exercise

Pattern 10: Stiffness and Decreased Ability to Relax

Laboratory approach in the evaluation of a suspected myopathy

Electrophysiologic Studies

The Muscle Biopsy

Molecular Genetic Studies

Other Tests

Summary

Web sites

This publication (or project) was supported by an Institutional Clinical and Translational Science Award, National Institutes of Health/National Center for Advancing Translational Sciences grant number UL1TR000001. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the National Institutes of Health.