CNS Pathology: Signs and Symptoms

Signs and Symptoms of CNS Pathology

• Alteration of consciousness can range from confusion to coma, with hyperarousal (restless, agitation, delirium) and hypoarousal (drowsiness to stupor or coma) being possible states.
• Small restricted lesions to the brainstem can cause stupor or coma, while massive lesions to the hemispheres can cause coma.
• Attention deficits, such as confusional states, can occur due to damage to the frontal and prefrontal areas responsible for mental control and concentration.
• Disturbances of higher brain function, including delusions, hallucinations, and memory impairments, can occur depending on the area affected.
• Language and speech impairments, such as dysarthria (disturbance in articulation), anarthria (lack of ability to produce speech), and expressive/receptive aphasia (disorder of language output), can result from damage to the frontal or temporal lobes.
• Alexia (inability to read), agraphia (inability to write), and apraxia (disorder of skilled purposeful movement) can occur due to lesions in various areas of the brain.
• Agnosia (inability to recognize objects), akinesia (partial/complete lack of voluntary movement), and ataxia (uncoordinated movement) are also possible symptoms.

Lobar Disorders

• Right hemisphere syndrome can result in the inability to orient the body with external space and generate a motor response, hemineglect, spatial disorientation, and problems with interpersonal relationships and socialization.
• Temporal and limbic lobe syndrome can involve disorders of primary emotions, such as pain, anger, pleasure, and fear.
• Frontal lobe syndrome can lead to personality changes, slow processing of information, lack of appropriate judgment, disinhibition, and apathy, as well as behavior problems.

Cerebellar Disorders

• Ataxia (uncoordinated movement), hypotonicity (decreased muscle tone), asthenia (generalized weakness), postural tremor, and dysmetria (underestimation or overestimation of movement causing an "intention tremor") are possible symptoms.
• Dysdiadochokinesis (inability to perform rapid alternating movement), scanning speech, and nystagmus (inability to hold gaze) can also occur.

Sensory Disturbances

• Lesions above the brainstem can affect the contralateral side, while lesions in the brainstem and below can affect the ipsilateral side.
• Sensory disturbances can manifest as a lack of tactile sensation, numbness, tingling, parasthesia, or loss of proprioception.

Causes of CNS Pathology

• Trauma can cause traumatic brain injury or spinal cord injury, often accompanied by tearing of blood vessels causing hemorrhage and death to tissue.
• Infection, including meningitis, encephalitis, and brain abscess, can cause damage to the CNS.
• Meningitis can be caused by bacteria or viruses, and can result in brain damage if not treated promptly.
• Encephalitis can be caused by viruses transmitted by mosquitoes, ticks, or herpes simplex, and can result in inflammation and damage to the gray matter of the CNS.
• Brain abscess can occur when microorganisms reach the brain and cause a local infection, and can result in fever, chills, headache, neurological symptoms, seizures, lethargy, and confusion.

Metabolic Disorders

• Phenylketonuria (PKU) is an autosomal recessive disorder that can produce severe mental retardation if not controlled by a low phenylalanine diet.
• Tay-Sachs disease is a rare genetic disorder that involves the accumulation of lipids in the brain.
• Wilson's disease is a rare genetic disorder that involves copper metabolism, with deposits forming in the liver and brain.

Toxins and Drugs

• Venom from snakes, spiders, and scorpions can contain neurotoxins that depress cardiac and respiratory centers or prevent transmission of nerve impulses.
• Metals such as lead, mercury, and arsenic, as well as insecticides, can be toxic to the CNS.
• Certain plants, such as curare, ergot, and some mushrooms, can be toxic to the CNS.
• Drugs, including barbiturates, cocaine, heroine, and alcohol, can also be toxic to the CNS.

Deficiencies

• Vitamin B deficiency can cause polyneuritis, and vitamin B12 deficiency can cause pernicious anemia, which can lead to changes in the spinal cord and peripheral nerves if not treated.

Degenerative Diseases

• Parkinson's disease, Alzheimer's disease, multiple sclerosis, and amyotrophic lateral sclerosis are all degenerative diseases that can affect the CNS.

Tumors

• Tumors can occur in the CNS and cause damage to surrounding tissue.

Congenital Defects

• Down Syndrome is a chromosomal defect that can cause language and cognitive delay.
• Dyslexia (word blindness) is a difficulty in recognizing letters, reading words, spelling, or writing.
• Anencephaly is a failure of the forebrain or brain to develop.
• Dysraphic malformations, including myelomeningocele, meningocele, and spina bifida occulta, can occur due to incomplete fusion of the neural tube.

This quiz covers the signs and symptoms of Central Nervous System (CNS) pathology, including alterations of consciousness and arousal levels. Test your knowledge of hyperarousal, hypoarousal, and coma.