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
Identifying the anatomy and pathophysiology of the lesion through careful history-taking and an accurate neurologic examination Introduction to the Neurologic Examination The purpose of the neurologic examination is to establish whether the patient’s brain, special senses, spinal cord, peripheral nerves, and muscle and skin receptors are functioning normally... read more markedly narrows the differential diagnosis and thus the number of tests needed. The history is important in identifying the likely site of neurologic dysfunction, and the neurologic examination is used to corroborate the suspected location. This approach should not be replaced by reflex ordering of CT, MRI, and other laboratory testing; doing so leads to error and unnecessary cost.
To identify the anatomic location, the examiner considers questions such as
Are all the symptoms and signs referable to a single lesion in the nervous system or to multiple lesions?
Is the central or peripheral nervous system involved, or are both involved?
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 lumbosacral plexus, peripheral nerves, neuromuscular junction, and muscle.
Once the location of the lesion is identified, categories of pathophysiologic causes are considered; they include those originating primarily in the nervous system and those originating elsewhere in the body and affecting the nervous system secondarily (eg, vascular, infectious, immune-mediated). General categories of causes for neurologic disorders include the following:
Vascular
Infectious
Neoplastic
Degenerative
Traumatic
Toxic-metabolic
Congenital
Immune-mediated
When appropriately applied, the neurologic method provides an orderly approach to even the most complex case, and clinicians are far less likely to be fooled by neurologic mimicry—eg, when symptoms of an acute stroke are actually due to a brain tumor or when rapidly ascending paralysis suggesting Guillain-Barré syndrome is actually due to spinal cord compression.
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 can be obtained or whether a family member should be interviewed instead.
History of present illness should include asking the patient about the following:
The quality, intensity, distribution, duration, and frequency of each symptom (questions should be specific)
The duration of symptoms to differentiate between acute, subacute, and chronic (including congenital) conditions
The circumstances that aggravate and attenuate the symptom
The effectiveness of past treatments
The order in which symptoms occur to help identify the cause
Symptoms not directly related to the nervous system, which suggest a generalized or systemic condition
Specific disabilities, described quantitatively (eg, walking at most 25 feet before needing to stop to rest) and their effect on the patient's daily routine.
Past medical history and a complete review of systems are essential because neurologic complications are common in other disorders, especially alcohol use disorder Alcohol Use Disorder and Rehabilitation Alcohol use disorder involves a pattern of alcohol use that typically includes craving and manifestations of tolerance and/or withdrawal along with adverse psychosocial consequences. Alcoholism... read more , diabetes Diabetes Mellitus (DM) Diabetes mellitus is impaired insulin secretion and variable degrees of peripheral insulin resistance leading to hyperglycemia. Early symptoms are related to hyperglycemia and include polydipsia... read more , cancer Overview of Cancer Cancer is an unregulated proliferation of cells. Its prominent properties are A lack of cell differentiation Local invasion of adjoining tissue Metastasis, which is spread to distant sites through... read more , vascular disorders, and HIV infection Human Immunodeficiency Virus (HIV) Infection Human immunodeficiency virus (HIV) infection results from 1 of 2 similar retroviruses (HIV-1 and HIV-2) that destroy CD4+ lymphocytes and impair cell-mediated immunity, increasing risk of certain... read more 
.
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.
Sometimes neurologic symptoms and signs are functional, reflecting a psychiatric disorder. Typically, such symptoms and signs do not conform to the rules of anatomy and physiology, and the patient may be depressed or unusually frightened. However, functional and physical disorders sometimes coexist, and distinguishing them can be challenging.
Physical Examination and Testing
A physical examination to evaluate all body systems is done, but the focus is on the nervous system (neurologic examination Introduction to the Neurologic Examination The purpose of the neurologic examination is to establish whether the patient’s brain, special senses, spinal cord, peripheral nerves, and muscle and skin receptors are functioning normally... read more ). The neurologic examination, discussed in detail elsewhere in THE MANUAL, includes the following:
In many situations, a cerebrovascular examination Cerebrovascular Examination In a patient presenting with acute stroke, radial pulse and BP in the 2 arms are compared to check for painless aortic dissection, which can occlude a carotid artery and cause stroke. The skin... read more also is done.
Diagnostic tests Computed Tomography (CT) in Neurologic Disorders Computed tomography (CT) provides rapid, noninvasive imaging of the brain and skull. CT is superior to magnetic resonance imaging (MRI) in visualizing fine bone detail in (but not the contents... read more 
may be needed to confirm a diagnosis or exclude other possible disorders.
