Chapter 12: Electroneurodiagnostic Assessment and Interpretation

Objectives

On completion of this chapter, the student/practitioner will be able to:

• Understand why the electroneurodiagnostic examination is an important diagnostic tool for rehabilitation professionals.

• Define the components of the electroneurodiagnostic examination.

• Discuss the purpose of the electroneurodiagnostic examination.

• Interpret the results of the electroneurodiagnostic examination and translate the results into clinical practice.

Key Terms

• Electromyography

• F wave

• Motor nerve conduction

• Sensory nerve conduction

Introduction

Electroneurodiagnostic studies are the natural physiological extension of the neurological physical examination. They are used to confirm, add to, or remove differential diagnoses suggested by clinical scripts taken from the history, prior diagnostic workup, and physical examination. This chapter is not meant to be a “how to” primer for the performance of the spectrum of electroneurodiagnostic testing; many other well-written texts are available. Rather, the author presents the subject of electroneurodiagnostic testing in a conceptualized state to allow the reader to develop an understanding of the various types of testing available and the clinical and diagnostic implications of normal and aberrant testing results and, for the rehabilitation clinician, to develop an appreciation of the ability of this powerful tool to facilitate diagnostics, goal setting, and interventional planning for patients with peripheral nerve injury.

In the performance of clinical testing, the electroneurodiagnostic clinician works to prove, disprove, or add to the differential diagnosis list via the scientific method. Clinical scripts provide differential diagnoses, and the clinician, through the use of various electroneurodiagnostic tests, collects data, develops the diagnostic hypotheses, collects more data, reworks the diagnostic hypothesis, and confirms or disproves the differential diagnosis. During the testing, the patient is awake and alert and can provide additional historical data if needed to the clinician. In contrast to many diagnostic studies, the electroneuromyogram does not have a strict procedural component; the clinician may perform as many or as few specific tests as needed to isolate a diagnosis. Electroneurodiagnostic testing is a unique test in that the patient by supplying the clinician with information during the study is an active partner in the diagnostic process.

The primary goal of the electroneurodiagnostic evaluation is to determine the site of the lesion; the findings do not identify the process leading to the aberrant findings. To obtain information about the “localization,” the following processes are used: motor nerve studies, sensory nerve studies, and needle electromyography (EMG). Correlation with aspects of the physical examination and other diagnostic tests is needed to isolate the diagnosis.

Electroneurodiagnostic Process

The complete electroneurodiagnostic process is as follows:

1. History taking: Following the development of the clinician-patient collaborative relationship, the clinician should take a thorough history of the present illness using open-ended questions and follow-up queries. Past ...