Chapter 18

Chapter 18: Disorders of the Central and Peripheral Nervous Systems and the Neuromuscular Junction

CNS Disorders

• Major focus on traumatic brain injuries, spinal cord injuries, cerebrovascular disorders, infection/inflammation of the CNS, headache syndromes, and tumors.

Traumatic Brain Injury (TBI)

Classifications of TBI

• Focal/Diffuse: Refers to localized damage vs. widespread damage.

• Closed/Open: Closed injuries occur without penetrating the skull, while open injuries cause direct exposure to brain tissue.

• Glasgow Coma Scale (GCS): A tool to assess consciousness; severe injury is indicated by loss of consciousness lasting 6 or more hours.

• Coup/Countrecoup: Damage occurs at the site of impact (coup) and on the opposite side of the brain (countrecoup).

TBI Complications

• Contusions can lead to:

  • Epidural (extradural) hematoma

  • Subdural hematoma

  • Intracerebral hematoma

Clinical Presentation of TBI

• Concussions

  • Complications include post-concussive syndrome, post-traumatic seizures, and chronic traumatic encephalopathy.

Postconcussive Syndrome Symptoms

• Headaches

• Nervousness or anxiety

• Irritability

• Insomnia

• Depression

• Forgetfulness and inability to concentrate

• Fatigability

• Treatment: Reassurance, symptomatic relief, and close observation for the first 24 hours.

Spinal Cord Injury

Primary/Secondary Injury

• Clinical Manifestations:

  • Spinal and neurogenic shock.

  • Complete loss of reflexes below the lesion level; signs include:

    • Flaccid paralysis

    • Sensory deficit

    • Loss of bladder and rectal control

  • Spinal Shock: Occurs shortly after injury, ranging from a few days up to 3 months.

  • Neurogenic Shock: Specifically resulting from cervical or upper thoracic injuries; characterized by loss of sympathetic activity.

Causes of Spinal Cord Compression

• Osteophytes

• Disruption of intervertebral disks

• Ligament compression

• Compression fractures, including wedge fractures that do not compress the cord.

Autonomic Dysreflexia

• Involves an exaggerated response of the autonomic nervous system; symptoms include hypertension, bradycardia, and flushing.

• Caused by visceral distention or painful stimuli below the level of lesion; involves complex reflexes stemming from the spinal cord.

Cerebrovascular Disorders

• Most frequently occurring neurologic disorder; major examples include:

  • Cerebrovascular Accidents (CVAs) or strokes

  • Transient Ischemic Attacks (TIAs)

  • Aneurysms or malformations

• Strokes are the fifth-leading cause of death in the U.S.

Types of Strokes

• Ischemic Stroke: Caused by blockage of a blood vessel.

  • Lacunar Stroke: A type of ischemic stroke occurring in the smaller blood vessels.

• Hemorrhagic Stroke: Caused by bleeding in the brain.

• Cryptogenic Stroke: Stroke of unknown origin.

Intracranial Aneurysms

• Types include:

  • Saccular (berry)

  • Fusiform (giant)

  • Mycotic

  • Traumatic (dissecting)

Vascular Malformations

• Includes cavernous angiomas, capillary telangiectasis, venous angioma, and arteriovenous malformation.

Headache Syndromes

• Common types of headaches:

  • Tension Headaches: Feel like a tight band around the head.

  • Migraine Headaches: Throbbing pain on one side, can worsen with movement.

  • Cluster Headaches: Severe pain around one eye.

CNS Infection and Inflammation

• Caused by bacteria, viruses, fungi, parasites, or mycobacteria, leading to:

  • Meningitis

  • Abscesses

  • Encephalitis

  • NeuroAIDS

• Cardinal signs: Fever, pain, and neurologic disorders.

Bacterial Meningitis Pathophysiology

• Stages:

  • Nasopharyngeal colonization and bacteremia.

  • Meningeal invasion leading to inflammation and symptoms including increased intracranial pressure and cerebral damage.

Demyelinating Disorders

• Types include:

  • Multiple Sclerosis: Immune-mediated damage to myelin.

  • Guillain-Barré Syndrome: Autoimmune response following an infection leading to nerve demyelination.

Peripheral Nervous System Disorders

• Neuropathies:

  • Generalized symmetric polyneuropathies

  • Generalized neuropathies

  • Focal or multifocal neuropathies

• Diabetic Neuropathy: Associated with poor circulation, pain, numbness, and foot ulcers.

Neuromuscular Junction Disorders

• Disorders associated with autoantibodies:

  • Myasthenia Gravis: Autoimmune attack on acetylcholine receptors.

  • Lambert-Eaton Myasthenic Syndrome: Autoantibodies affecting calcium channels at nerve terminals.

Brain Tumors

• Types include gliomas, meningiomas, and metastatic tumors, leading to various neurological symptoms including headaches and cognitive deficits.