Components of a Neurological Evaluation
Clinical and Laboratory Assessment of Nervous System Disorders
Jul 5, 2009
The medical community knows about many neurological conditions, such as stroke, seizure disorder, and multiple sclerosis. As with any clinical problem, a patient with a neurological issue undergoes an evaluation by a physician to diagnose the condition. This involves a variety of general steps as well as procedures specific to the realm of neurology.
Patient History
When a physician, such as a neurologist, takes a patient history, he or she asks questions about the presenting neurological symptom, whether it involves generalized weakness, focal muscle weakness, sensory loss, numbness and tingling (paresthesias), imbalance, or other complaint. The patient provides information that helps the clinician understand the symptom, its timing, and its situational context. In addition, the physician explores various non-neurological medical issues in case they are related to the present neurological issue.
Physical Exanimation
A physical examination of the patient's body elicits additional diagnostic information. The neurological portion of the exam begins with the assessment of mental status, which refers to the ability to pay attention and perform other higher-level cognitive functions, such as judgment and orientation to self, place, and time.
The neurological exam also includes maneuvers to test the 12 cranial nerves that emerge from the brain itself. Their major functions are as follows:
- Cranial Nerve I (Olfactory Nerve): Sense of smell (rarely necessary to test in most cases)
- Cranial Nerve II (Optic Nerve): Sense of sight
- Cranial Nerve III (Oculomotor Nerve): Movement of eye muscles and constriction of the pupils
- Cranial Nerve IV (Trochlear Nerve): Movement of eye muscles
- Cranial Nerve V (Trigeminal Nerve): Facial sensation and movement of the jaw
- Cranial Nerve VI (Abducens Nerve): Movement of the lateral eye muscles
- Cranial Nerve VII: (Facial Nerve): Movement of the facial muscles
- Cranial Nerve VIII (Vestibulocochlear Nerve): Sense of hearing and equilibrium
- Cranial Nerve IX (Glossopharyngeal Nerve): Gag reflex
- Cranial Nerve X (Vagus Nerve): Gag reflex and elevation of the palate
- Cranial Nerve XI (Spinal Accessory Nerve): Movement of the sternocleidomastoid (SCM) muscle to turn the head and trapezius muscle to lift the shoulders
- Cranial Nerve XII (Hypoglossal Nerve): Movement of the tongue
Similar types of tests are done with the rest of the body. Strength testing for each of the arm and leg muscles assesses motor function. The use of sharp tips and tuning forks evaluates pain sensation (nociception) and vibration sense, respectively, while movement of the patient's digits, such as the big toe, can assess positional awareness (proprioception). Other steps include the evaluation of deep tendon reflexes using a reflex hammer and the assessment of gait and coordination.
Laboratory and Imaging Studies
Laboratory testing includes general blood tests, such as a complete blood count and chemistry panel, to rule out medical conditions that have neurological implications. Depending on the suspected condition, evaluation may also include computed tomography (CT) and magnetic resonance imaging (MRI) of the brain or spinal cord, a biopsy of abnormal tissue, and a lumbar puncture in which spinal cord fluid is extracted and analyzed.
Neurological Function Studies
In some situations, a neurological evaluation requires function testing on certain parts of the nervous system. This is done using at least one of the following tests:
- Nerve Conduction Studies: Nerve conduction studies entail the stimulation of a peripheral nerve and recording the time it takes for the impulse to stimulate contraction of the muscle innervated by the nerve.
- Electromyography (EMG): Often performed in conjunction with nerve conduction studies, EMG records muscle activity through a needle inserted directly into the muscle.
- Electroencephalography (EEG): EEG records brain activity via surface electrodes on the head and may suggest particular diagnoses based on wave patterns.
- Evoked Potentials: Evoked potentials refer to the use of auditory, tactile, and visual stimuli to trigger activity in specific portions of the cerebral cortex.
References
- Merck Manual - Approach to the Neurologic Patient
- National Institute of Neurological Disorders and Stroke (NINDS) - Neurological Diagnostic Tests and Procedures
 |
