1. Evaluation of the Neurologic Patient

2. Patients with neurologic symptoms are approached in a stepwise manner termed the neurologic method, which consists of the following
Identifying the anatomic location of the lesion or lesions causing symptoms
Identifying the pathophysiology involved
Generating a differential diagnosis
Selecting specific, appropriate tests

3. Identifying the anatomy and pathophysiology of the lesion through careful history taking and an accurate neurologic examination markedly narrows the differential diagnosis and thus the number of tests needed. This approach should not be replaced by reflex ordering of CT, MRI, and other laboratory testing; doing so leads to error and unnecessary cost

4. To identify the anatomic location, the examiner considers questions such as
Is the lesion in one or multiple locations
Is the lesion confined to the nervous system, or is it part of a systemic disorder?
What part of the nervous system is affected

5. Specific parts of the nervous system to be considered include the cerebral cortex, subcortical white matter, basal ganglia, thalamus, cerebellum, brain stem, spinal cord, brachial or pelvic plexus, peripheral nerves, neuromuscular junction, and muscle

6. Once the location of the lesion is identified, categories of pathophysiologic causes are considered; they include
Vascular
Infectious
Neoplastic
Degenerative
Traumatic
Toxic-metabolic
Immune mediated

7. History
The history is the most important part of the neurologic evaluation. Patients should be put at ease and allowed to tell their story in their own words. Usually, a clinician can quickly determine whether a reliable history is forthcoming or whether a family member should be interviewed instead

8. Specific questions clarify the quality, intensity, distribution, duration, and frequency of each symptom. What aggravates and attenuates the symptom and whether past treatment was effective should be determined. Asking the patient to describe the order in which symptoms occur can help identify the cause.

9. Specific disabilities should be described quantitatively (eg, walks at most 25 ft before stopping to rest), and their effect on the patient's daily routine noted. Past medical history and a complete review of systems are essential because neurologic complications are common in other disorders, especially alcoholism, diabetes, cancer, vascular disorders, and HIV infection.

10. Family history is important because migraine and many metabolic, muscle, nerve, and neurodegenerative disorders are inherited. Social, occupational, and travel history provides information about unusual infections and exposure to toxins and parasites

11. Sometimes neurologic symptoms and signs are functional or hysterical, reflecting a psychiatric disorder. Typically, such symptoms and signs do not conform to the rules of anatomy and physiology, and the patient is often depressed or unusually frightened. However, functional and physical disorders sometimes coexist, and distinguishing them can be challenging.

12. Neurological examination

13. Diagnostic procedures
. Diagnostic procedures should not be used for preliminary screening, except perhaps in emergencies when a complete neurologic evaluation is impossible. Evidence uncovered during the history and physical examination should guide testing

14. Lumbar puncture is used to evaluate intracranial pressure and CSF composition (see see Cerebrospinal Fluid Abnormalities in Various Disorders ), to therapeutically reduce intracranial pressure (eg, pseudotumor), and to administer intrathecal drugs or a radiopaque dye for myelography

15. CT provides rapid, noninvasive imaging of the brain and skull
MRI provides better resolution of neural structures than CT. This difference is most significant clinically for visualizing cranial nerves, brain stem lesions, abnormalities of the posterior fossa, and the spinal cord; CT images of these regions are often marred by bony streak artifacts. Also, MRI is better for detecting demyelinating plaques, early infarction, subclinical brain edema, cerebral contusions, incipient transtentorial herniation, abnormalities of the craniocervical junction, and syringomyelia. MRI is especially valuable for identifying spinal abnormalities (eg, tumor, abscess) compressing the spinal cord and requiring emergency intervention

16. Myelography X-rays are taken after a radiopaque agent is injected into the subarachnoid space via lumbar puncture
EEG
Electrodes are distributed over the brain to detect electrical changes associated with seizure disorders, sleep disorders, and metabolic or structural encephalopathies. Twenty electrodes are distributed symmetrically over the scalp

17. Measurement of evoked responses (potentials)
Visual, auditory, or tactile stimuli are used to activate corresponding areas of the cerebral cortex, resulting in focal cortical electrical activity. Ordinarily, these small potentials are lost in EEG background noise, but computer processing cancels out the noise to reveal a waveform. Latency, duration, and amplitude of the evoked responses indicate whether the tested sensory pathway is intact

18. Electromyography and nerve conduction studies
When determining whether weakness is due to a nerve, muscle, or neuromuscular junction disorder is clinically difficult, these studies can identify the affected nerves and muscles
Biopsy
Nerve and muscle biopsy are usually done simultaneously