Neurological Disorders

Tumors and Seizures

• Types of Tumors

  • Malignant (cancerous):

  • Grow by infiltrating the surrounding tissue

  • Can produce metastases

  • Benign (harmless):

  • Especially if encapsulated

  • Damage brain tissue mainly through compression or infiltration

• Causes of Tumors

  • Tumors do not arise from nerve cells but from other cells like glial cells or may originate as metastases from other parts of the body.

  • Serious types include metastases and gliomas.

• Types of Tumors (originating cells):

  • Gliomas: arisen from glial cells

  • Glioblastoma: from glial cells

  • Astrocytoma: from astrocytes

  • Ependymoma: from ependymal cells lining ventricles

  • Oligodendrocytoma: from oligodendrocytes

  • Meningioma: from cells of the meninges

  • Neurinoma: from Schwann cells or connective tissue cells covering cranial nerves

  • Angioma: from blood vessel cells

  • Pinealoma: from pineal gland cells

• Symptoms and Effects:

  • A large benign tumor (e.g., meningioma) can displace brain structures.

• Treatment:

  • Surgery: removal of the tumor (especially if encapsulated)

  • Radiation therapy: targets remaining cells

  • Chemotherapy: may be effective for some tumors

Seizures

• Definition: A sudden, excessive activity of cerebral neurons.

  • If the motor system is involved, it may cause convulsions, though not all seizures result in this.

  • Seizure disorders can arise from multiple causes.

• Categories of Seizures:

  • Partial Seizures (localized):

  • Simple: may cause changes in consciousness

  • Complex: may lead to loss of consciousness

  • Generalized Seizures (widespread):

  • Grand Mal (Tonic-clonic): most severe, often preceded by an aura

  • Absence Seizures: common in children, cause unresponsiveness

• Effects of Seizures:

  • Brain damage correlates with seizure frequency and severity; often due to excessive glutamate release.

• Causes:

  • Scarring, high fever, chronic drug/alcohol withdrawal, idiopathic cases, and genetic factors.

• Treatment:

  • Anticonvulsant drugs: Mostly GABAergic, enhancing inhibitory synapses.

  • Brain surgery: effective if tumors are identified.

Cerebrovascular Accidents

• Types:

  • Hemorrhagic Strokes: caused by brain bleeding (often from high blood pressure).

  • Ischemic Strokes: due to blood flow obstructions (thrombus or embolus formation).

• Mechanism of Neuron Death:

  • Excess glutamate leads to excitotoxicity, contributing to neuron death.

• Treatments:

  • Medications to lower blood pressure.

  • Surgical intervention to repair blood vessels or remove blood clots.

  • Anticoagulant drugs (like tPA) to dissolve clots, and anti-inflammatory drugs.

• Follow-Up Therapy:

  • Physical, speech, and occupational therapy.

  • Constraint-induced movement therapy and brain-computer interfaces.

Traumatic Brain Injury

• Types:

  • Open-head injuries: skull fractures leading to brain wounds.

  • Closed-head injuries: impacts without skull penetration.

• Chronic Traumatic Encephalopathy (CTE): Resulting from repeated head trauma, leading to neurodegeneration.

  • Affects mood and cognitive control.

• Treatment:

  • Vigorous efforts to reduce swelling and ensure circulation.

  • Drugs to inhibit glutamate release.

Degenerative Disorders

• Transmissible Spongiform Encephalopathies (TSE): Fatal brain diseases caused by prions.

  • Cause brain to appear spongy; examples include BSE and Creutzfeldt-Jakob disease.

• Parkinson’s Disease: Degeneration of dopamine neurons, often due to environmental toxins.

• Huntington’s Disease: Genetic disorder affecting basal ganglia leading to uncontrollable movements.

• Amyotrophic Lateral Sclerosis (ALS): Targets motor neurons leading to muscle weakness and atrophy.

• Multiple Sclerosis: An autoimmune disorder causing demyelination of neurons; women are more frequently affected.

• Alzheimer’s Disease: Most common dementia. Involves memory loss due to accumulation of beta-amyloid and tau proteins.

• Korsakoff's Syndrome: Anterograde amnesia caused by chronic alcohol consumption, leading to thiamine deficiency.

Disorders from Infectious Diseases

• Encephalitis: Infection causing widespread brain inflammation; symptoms include fever, convulsions.

• Meningitis: Involves inflammation of meninges; symptoms include stiff neck and confusion; can cause severe complications.

• Comparison:

  • Meningitis: Inflammation of meninges.

  • Encephalitis: Inflammation of the brain itself.

Tonic and clonic are terms often used to describe the phases of a grand mal seizure (also known as a tonic-clonic seizure). During a tonic seizure, the muscles become stiff, and the individual may lose consciousness. The clonic phase follows, characterized by rhythmic jerking or convulsions of the limbs due to rapid muscle contractions and relaxations.