Examination of the Patient With Weakness Or Sensory Loss
GOAL
The goal of examining the patient with weakness or sensory loss is to try to determine the localization and mechanism of the neurologic problem causing the symptoms.
PATHOPHYSIOLOGY
Weakness
The basic neuroanatomy of the motor pathways in the central and peripheral nervous system is outlined in Chapter 24, Approach to the Motor Examination. Weakness can occur due to any kind of lesion affecting the upper motor neuron within the brain or spinal cord, or affecting the lower motor anywhere from the anterior horn cells of spinal cord to the nerve roots, plexus, peripheral nerves, neuromuscular junction, or muscles. Note that the term weakness here means any true muscle weakness less than 5 out of 5 (see Chapter 24, Approach to the Motor Examination) and not a subjective generalized sense of fatigue (also called asthenia); fatigue is a nonspecific and nonlocalizing symptom that can be seen in many systemic and neurologic illnesses.
Sensory Loss
The basic neuroanatomy of the sensory pathways in the central and peripheral nervous system is outlined in Chapter 28, Approach to the Sensory Examination. Sensory symptoms (such as numbness and tingling) can occur due to any kind of lesion affecting the sensory pathways in the central or peripheral nervous system.
TAKING THE HISTORY OF A PATIENT WITH WEAKNESS OR SENSORY LOSS
The history of the patient with a complaint of weakness or sensory loss should be obtained with the goal of looking for additional clues that may help you determine the localization and mechanism of the problem.
For a complaint of weakness, during the history, try to pinpoint the areas involved in the weakness (e.g., which extremities are weak or which movements of an extremity are weak), because lesions in various regions of the central and peripheral nervous system produce characteristic patterns of weakness (see Table 24-3). For example, weakness of one side of the body suggests the possibility of a contralateral cerebral hemispheric localization, whereas distal weakness in the lower extremities suggests the possibility of a peripheral neuropathic process. When neuromuscular junction disease (i.e., myasthenia gravis) is a consideration, make sure to ask about any waxing and waning of the weakness, especially worsening at the end of the day, as well as any symptoms of dysarthria, dysphagia, ptosis, or diplopia.
For a complaint of sensory loss, ask the patient to point to the area or areas involved, because lesions in various regions of the central and peripheral nervous system produce characteristic patterns of sensory loss (see Table 28-2). For example, analogous to weakness, numbness of one side of the body suggests the possibility of a contralateral cerebral hemispheric (or thalamic) localization, whereas distal numbness in the lower extremities suggests the possibility of a peripheral neuropathic process.Related posts:
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