The central nervous system (CNS) is the body's major communication network. Because of localization of functions, neurologic deficits related to disease processes are variable in their presentation. In certain locations of the brain, a lesion will cause minimal or no symptoms, whereas in other areas, it will cause major neurologic deficits. CNS disease can present in many ways, including changes in consciousness, focal neurologic deficits (e.g., aphasia and amnesia, motor and sensory defects), headaches, dizziness, and seizures. Knowledge of the various neurologic pathways will allow a physician to localize the cause of the patient's symptoms.
CNS diseases are classified within one of many categories, including vascular diseases (e.g., infarcts and spontaneous hemorrhages), trauma, infections, neoplasms, degenerative diseases, toxic and metabolic disorders, and demyelinating diseases. Because the pathology of nervous system diseases is intimately related to their neurologic manifestations, this chapter will begin with a discussion of clinical presentations of central nervous system disorders. This will be followed by a discussion of basic pathologic changes, malformations, vascular diseases, traumatic disorders, infections of the CNS, neoplasms, degenerative diseases, demyelinating disorders, and, finally, a few basic peripheral nerve and skeletal muscle disorders.
Requirement for consciousness: Intact and functioning brainstem reticular activating system and its cortical projections.
Terminology for impaired levels of consciousness, in order of increasing severity
- Confusion: Impairment of the capacity to think with normal speed and clarity, associated with inattentiveness and disorientation. Delirium is a special example of an acute confusional state in which impaired attention and reasoning are associated with agitation, hallucinations, and in some cases, tremor and convulsions.
- Drowsiness: Inability to remain awake without external stimulation; often associated with some degree of confusion.
- Stupor: State in which only vigorous external stimulation can arouse the patient; once aroused, responses remain markedly impaired.
- Coma: Deep sleep-like state; patient cannot be aroused even with vigorous or repeated external stimulation.
Causes of change in consciousness
With abnormal CT scan
- Hemispheric mass lesions that cross the midline or impinge upon the brainstem.
- Brainstem lesions that directly affect the reticular formation.
- Subarachnoid hemorrhage.
With normal CT scan
- Inflammatory disorders, such as bacterial meningitis and viral encephalitis.
- Exogenous toxins, such as sedative drugs, alcohols, opioids, and carbon monoxide.
- Endogenous metabolic insults, such as global hypoxic-ischemic insults, hypoglycemia, hyperammonemia, and hypercalcemia.
- Postictal state.
- Selective brainstem ischemia.
Diagnosis of cause of changes in consciousness: Establishing a differential diagnosis for the cause of a patient's change in consciousness requires evaluation of the history preceding the change, the physical examination, and the effectiveness of initial empirical therapy.
Categories of cause of changes in consciousness
- Toxic and metabolic (e.g., opiate overdose, alcohol).
- Infectious (e.g., meningitis, encephalitis, septic shock).
- Cerebrovascular (e.g., stroke).
- Other (e.g., seizures, neoplasms).
Role of history in diagnosis of changes in consciousness
- Preceding headache suggests meningitis, subarachnoid hemorrhage, or encephalitis.
- Preceding intoxication, ...
Log In to View More
If you don't have a subscription, please view our individual subscription options below to find out how you can gain access to this content.
Want remote access to your institution's subscription?
Sign in to your MyAccess profile while you are actively authenticated on this site via your institution (you will be able to verify this by looking at the top right corner of the screen - if you see your institution's name, you are authenticated). Once logged in to your MyAccess profile, you will be able to access your institution's subscription for 90 days from any location. You must be logged in while authenticated at least once every 90 days to maintain this remote access.
If your institution subscribes to this resource, and you don't have a MyAccess profile, please contact your library's reference desk for information on how to gain access to this resource from off-campus.
AccessPhysiotherapy Full Site: One-Year Subscription
Connect to the full suite of AccessPhysiotherapy content and resources including interactive NPTE review, more than 500 videos, Anatomy & Physiology Revealed, 20+ leading textbooks, and more.
Pay Per View: Timed Access to all of AccessPhysiotherapy
24 Hour Subscription $34.95
48 Hour Subscription $54.95
Pop-up div Successfully Displayed
This div only appears when the trigger link is hovered over.
Otherwise it is hidden from view.