Manual Muscle Testing: A Method of Measuring Extremity Muscle Strength Applied to Critically Ill Patients

Summary

Survivors of acute respiratory distress syndrome (ARDS) and critical illness frequently develop long-lasting muscle weakness. Manual muscle testing (MMT) is a standardized clinical examination commonly used to measure strength of peripheral skeletal muscle groups. This video demonstrates MMT using the 6-point Medical Research Council scale.

Abstract

Survivors of acute respiratory distress syndrome (ARDS) and other causes of critical illness often have generalized weakness, reduced exercise tolerance, and persistent nerve and muscle impairments after hospital discharge.^1-6 Using an explicit protocol with a structured approach to training and quality assurance of research staff, manual muscle testing (MMT) is a highly reliable method for assessing strength, using a standardized clinical examination, for patients following ARDS, and can be completed with mechanically ventilated patients who can tolerate sitting upright in bed and are able to follow two-step commands. ^{7, 8}

This video demonstrates a protocol for MMT, which has been taught to ≥43 research staff who have performed >800 assessments on >280 ARDS survivors. Modifications for the bedridden patient are included. Each muscle is tested with specific techniques for positioning, stabilization, resistance, and palpation for each score of the 6-point ordinal Medical Research Council scale.^7,9-11 Three upper and three lower extremity muscles are graded in this protocol: shoulder abduction, elbow flexion, wrist extension, hip flexion, knee extension, and ankle dorsiflexion. These muscles were chosen based on the standard approach for evaluating patients for ICU-acquired weakness used in prior publications. ^1,2.

Protocol

1. Introduction

During manual muscle testing (MMT), each muscle group is tested bilaterally. For demonstration purposes, only one side is tested in this video for each of the 6 muscle groups. One hand of the examiner applies resistance or palpates the muscle or tendon for contraction while the other hand stabilizes the extremity being tested to keep it in the test position. The test is repeated if the patient does not understand the instructions or is not applying maximum effort.

2. Grading follows the Medical Research Council (MRC) system (Table 1).¹

Figure 1 illustrates an....

Discussion

Depending on the diagnostic criteria, 9 – 87% of ICU patients develop neuromuscular complications, which are associated with prolonged mechanical ventilation, increased hospital stay and rehabilitation time, and potentially associated with increased mortality.^1,2,16-18 Periodic reassessment of muscle strength, using a reliable method which minimizes inter-rater variability is helpful to detect changes over time. An important limitation of MMT using the MRC score system is the 6-point ordinal scale. M.......