Neurologic symptoms vary greatly because the nervous system controls many different body functions. Symptoms can include all forms of pain and can involve muscle function, sensation, interpretation of sensory stimuli, the special senses (vision, taste, smell, and hearing), sleep, awareness (consciousness), and mental function (cognition). The following are some examples:
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. While doing the examination, clinicians should relate findings to anatomic structures in the nervous system. With this information, the differential diagnosis of the disorder causing the patient’s symptoms can be more focused. Repeated neurologic examinations can help evaluate the course of the patient’s illness and/or response to treatment.
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 of) the posterior fossa, base of the skull, and spinal canal.
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.
Headache is pain in any part of the head, including the scalp, face (including the orbitotemporal area), and interior of the head. Headache is one of the most common reasons patients seek medical attention.
In lumbar puncture (LP), a needle is inserted into the lumbar subarachnoid space to collect cerebrospinal fluid (CSF) for laboratory testing, to measure CSF pressure, and sometimes to give intrathecal diagnostic or therapeutic agents.
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 older people. 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.
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 enable neurons to communicate with each other. 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. Other factors, including drugs and disorders, affect communication between neurons by modulating the production and actions of neurotransmitters including
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.
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 electroencephalography (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).
Almost half of all people in the US report sleep-related problems. Disordered sleep can cause emotional disturbance, memory difficulty, poor motor skills, decreased work efficiency, and increased risk of traffic accidents. It can even contribute to cardiovascular disorders and mortality.