Skip to Main Content

++

ABSTRACT

++

Patients who present with weakness may be left with marked disability unless a diagnosis is made quickly. The motor divisions of the nervous system are responsible for every movement a person makes. Any injury to the motor parts will have a direct consequence on one’s ability to perform meaningful motions. Motor disorders can cause a variety of weakness patterns; therefore, it is important for the reader to recognize that the disorders mentioned in this chapter are not restricted to a specific pattern and have tremendous overlap. In this chapter, readers will review patterns of weakness in specific motor disorders of the nervous system.

++

INTRODUCTION

++

The motor parts of the nervous system are responsible for every movement a person makes. Any injury to the motor division will have a direct consequence on one’s ability to perform meaningful motions. Therefore, it is vital to identify sources of motor injury in order to assist patients in regaining the ability to move. The purpose of this chapter is to identify patterns of weakness in specific motor disorders of the nervous system (Table 28-1). Motor disorders can cause a variety of weakness patterns; therefore, it is important for the reader to recognize that the disorders mentioned in this chapter are not restricted to a specific pattern and have tremendous overlap. Further descriptions of each disorder can be found in subsequent chapters in much more detail and are beyond the scope of this chapter.

++
Table Graphic Jump Location
Table 28-1.

Patterns of Weakness With Associated Motor Disorder Localization and Common Etiologies

++

ELEMENTS OF THE MOTOR EXAMINATION

++

Several objective assessments can be performed to ascertain a pattern of weakness in order to better localize the neurologic dysfunction involved in a patient’s presentation of weakness. Common motor assessments include power, muscle bulk, tone, and muscle stretch reflexes (MSRs). Motor examination findings differentiating upper from lower motor neuron injury can be found in Table 28-2.

  • Power: Muscle power (strength) can be objectively tested using the Medical Research Council motor grading system.1

    • Grade 5: Strength normal against resistance.

    • Grade 4: Reduced strength but can still move joints against resistance.

    • Grade 3: Movements against gravity but not against resistance.

    • Grade 2: Movements only with the elimination of gravity.

    • Grade 1: Only fasciculations are noticed, and no movement is observed.

    • Grade ...

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.