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natomically and functionally, the brain is the most
complex structure in the body. It controls our abil-
ity to think, our awareness of things around us, and
our interactions with the outside world. Signals to and
from various parts of the body are controlled by very
specific areas in the brain. Therefore, the brain is much
more vulnerable to lesions that in other organs might
produce no significant effects. For example, an isolated
renal infarct would not be expected to have a significant
effect on kidney function, whereas an infarct of compa-
rable size in a specific area of the brain could produce
complete paralysis on one side of the body. Alterations
in brain function can result from injury, cerebrovascu-
lar disease, infection, tumors, disruptions in electrical
activity (seizures), or impairment of memory (impaired
cognition or dementia).
Brain Injury
The brain is protected from external forces by the rigid
confines of the skull and the cushioning afforded by
the cerebrospinal fluid (CSF). The metabolic stability
required by its electrically active cells is maintained by a
number of regulatory mechanisms, including the blood–
brain barrier and autoregulatory mechanisms that ensure
adequate blood supply.
Mechanisms of Brain Injury
Injury to brain tissue can result from a number of condi-
tions, including trauma, infections, tumors, and degen-
erative processes. Brain damage resulting from these
disorders involves several common pathways, including
hypoxia and ischemia, the effects of excitatory amino
acid injury, and cerebral edema. In many cases the
mechanisms are interrelated.
Hypoxic and Ischemic Injury
The brain relies on the ability of the cerebral circula-
tion to deliver sufficient oxygen for its energy needs.
Although the brain makes up only 2% of the body
A
Disorders of
Brain Function
37
C h a p t e r
Brain Injury
Mechanisms of Brain Injury
Hypoxic and Ischemic Injury
Excitatory Amino Acid Injury
Cerebral Edema
Increased Intracranial Pressure, Herniation,
and Hydrocephalus
Brain Herniation
Hydrocephalus
Traumatic Brain Injury
Contusions
Hematomas
Concussions
Diffuse Axonal Injury
Manifestations of Diffuse Brain Injury
Consciousness
Other Manifestations of Deteriorating
Brain Function
Cerebrovascular Disease
The Cerebral Circulation
Regulation of Cerebral Blood Flow
Stroke (Brain Attack)
Ischemic Stroke
Hemorrhagic Stroke
Acute Stroke Management
Poststroke Management and Deficits
Intracranial Hemorrhage
Aneurysmal Subarachnoid Hemorrhage
Arteriovenous Malformations
Infections
Meningitis
Acute Bacterial Meningitis
Viral Meningitis
Encephalitis
Brain Tumors
Types of Tumors
Neuroglial Tumors
Medulloblastomas
Meningiomas
Primary Central Nervous System
Lymphomas
Metastatic Tumors
Manifestations
Diagnosis and Treatment
Seizure Disorders
Provoked Seizures
Febrile Seizures
Unprovoked (Epileptic) Seizures
Focal Seizures
Generalized Seizures
Diagnosis and Treatment
Antiepileptic Drug Therapy
Surgical and Neurostimulation Therapy
Generalized Convulsive Status Epilepticus
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