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.