Neurologic Disorders

Patients with neurologic symptoms are approached in a stepwise manner termed the neurologic method, which consists of the following:

Memory loss is a common complaint in the primary care setting. It is particularly common among the elderly but also may be reported by younger people. Sometimes family members rather than the patient report the memory loss (typically in an elderly person, often one with dementia).

The neurologic examination begins with careful observation of the patient entering the examination area and continues during history taking. The patient should be assisted as little as possible, so that difficulties in function can become apparent. The patient’s speed, symmetry, and coordination while moving to the examining table are noted, as are posture and gait. The patient’s demeanor, dress, and responses provide information about mood and social adaptation. Abnormal or unusual speech, use of language, or praxis; neglect of space; unusual posturing; and other disorders of movement may be apparent before formal testing.

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 of) the posterior fossa, base of the skull, and spinal canal.

The autonomic nervous system regulates physiologic processes. Regulation occurs without conscious control, ie, autonomously. The 2 major divisions are the

Brain infections can be caused by viruses, bacteria, fungi, or, occasionally, protozoa or parasites.

Coma is unresponsiveness from which the patient cannot be aroused and in which the patient's eyes remain closed. Impaired consciousness refers to similar, less severe disturbances of consciousness; these disturbances are not considered coma. The mechanism for coma or impaired consciousness involves dysfunction of both cerebral hemispheres or of the reticular activating system (also known as the ascending arousal system). Causes may be structural or nonstructural (eg, toxic or metabolic disturbances). Damage may be focal or diffuse. Diagnosis is clinical; identification of cause requires laboratory tests and neuroimaging. Treatment is immediate stabilization and specific management of the cause. For long-term coma, adjunctive treatment includes passive range-of-motion exercises, enteral feedings, and measures to prevent pressure ulcers.

Craniocervical junction abnormalities are congenital or acquired abnormalities of the occipital bone, foramen magnum, or first two cervical vertebrae that decrease the space for the lower brain stem and cervical cord. These abnormalities can result in neck pain; syringomyelia; cerebellar, lower cranial nerve, and spinal cord deficits; and vertebrobasilar ischemia. Diagnosis is by magnetic resonance imaging (MRI) or computed tomography (CT). Treatment often involves reduction, followed by stabilization via surgery or an external device.

Delirium (sometimes called acute confusional state) and dementia are the most common causes of cognitive impairment, although affective disorders (eg, depression) can also disrupt cognition. Delirium and dementia are separate disorders but are sometimes difficult to distinguish. In both, cognition is disordered; however, the following helps distinguish them:

Myelin sheaths cover many nerve fibers in the central and peripheral nervous system; they accelerate axonal transmission of neural impulses. Disorders that affect myelin interrupt nerve transmission; symptoms may reflect deficits in any part of the nervous system.

The cerebrum is divided by a longitudinal fissure into 2 hemispheres, each containing 6 discrete lobes:

Intracranial tumors may involve the brain or other structures (eg, cranial nerves, meninges). The tumors usually develop during early or middle adulthood but may develop at any age; they are becoming more common among the elderly. Brain tumors are found in about 2% of routine autopsies.

Meningitis is inflammation of the meninges and subarachnoid space. It may result from infections, other disorders, or reactions to drugs. Severity and acuity vary. Findings typically include headache, fever, and nuchal rigidity, Diagnosis is by cerebrospinal fluid (CSF) analysis. Treatment includes antimicrobial drugs as indicated plus adjunctive measures.

Voluntary movement requires complex interaction of the corticospinal (pyramidal) tracts, basal ganglia, and cerebellum (the center for motor coordination) to ensure smooth, purposeful movement without extraneous muscular contractions.

Dysfunction of certain cranial nerves may affect the eye, pupil, optic nerve, or extraocular muscles and their nerves; thus, they can be considered cranial nerve disorders, neuro-ophthalmologic disorders, or both. Neuro-ophthalmologic disorders may also involve dysfunction of the central pathways that control and integrate ocular movement and vision. Cranial nerve disorders can also involve dysfunction of smell, vision, chewing, facial sensation or expression, taste, hearing, balance, swallowing, phonation, head turning and shoulder elevation, or tongue movements (see table Cranial Nerves). One or more cranial nerves may be affected.

A neuron generates and propagates an action potential along its axon, then transmits this signal across a synapse by releasing neurotransmitters, which trigger a reaction in another neuron or an effector cell (eg, muscle cells, most exocrine and endocrine cells). Neurotransmitters that are released bind to receptors on another neuron. Neurons that release neurotransmitters are called presynaptic neurons. Neurons that receive neurotransmitter signals are called postsynaptic neurons. The signal may stimulate or inhibit the receiving cell, depending on the neurotransmitter and receptor involved.

Pain is the most common reason patients seek medical care.

The peripheral nervous system refers to parts of the nervous system outside the brain and spinal cord. It includes the cranial nerves and spinal nerves from their origin to their end. The anterior horn cells, although technically part of the central nervous system (CNS), are sometimes discussed with the peripheral nervous system because they are part of the motor unit.

Prion diseases are progressive, fatal, and untreatable degenerative brain disorders.

A seizure is an abnormal, unregulated electrical discharge that occurs within the brain’s cortical gray matter and transiently interrupts normal brain function. A seizure typically causes altered awareness, abnormal sensations, focal involuntary movements, or convulsions (widespread violent involuntary contraction of voluntary muscles). Diagnosis may be clinical and involves results of neuroimaging, laboratory testing, and EEG for new-onset seizures or levels of antiseizure drugs (anticonvulsants) for previously diagnosed seizure disorders. Treatment includes elimination of the cause if possible, antiseizure drugs, and surgery (if the drugs are ineffective).

Spinal cord disorders can cause permanent severe neurologic disability. For some patients, such disability can be avoided or minimized if evaluation and treatment are rapid.

Strokes are a heterogeneous group of disorders involving sudden, focal interruption of cerebral blood flow that causes neurologic deficit. Strokes can be