Neurological Disorders – 28/03/12
-uncontrollable growth of cells that has no function.
i) Benign – encapsulated – tumor has distinct border b/w tumor and surround. A surgeon can remove it
ii) Malignant – infiltrates the surrounding tissue. No distinction. Can give rise to metastasis in which
tumor cells go through the vascular system and grow elsewhere.
Any tumor in the brain is harmful. Two ways:
1) Occupies space and compresses the tissue or block the flow of CSF.
2) The tumor invades the surrounding tissue as it grows and destroys the cells in it’s path.
Glioma (tumors of the glial cells) is the most common and serious type of tumor.
Ependymoma (ependymal cells in the ventricle)
Meduloblastoma (cells in roof of fourth ventricle)
Seizure Disorders (Epilepsy)
-sudden, excessive activity of cerebral neurons. In the motor region = convulsion.
Partial seizures have a definite focus and remain localized. Simple partial seizures involve changes to
consciousness. Complex partial seizures lead to loss of consciousness.
Diagnosis relies on EEG, epilepsy is associated with bursts of high amplitude EEG spikes which occur
during an attack.
Simple seizures during sleep ARE NOT sleep disorders and occur during REM
Generalized Seizures (Grand Mal)
-widespread involving most of the brain. A grand mal seizure is the most severe. Proceeding the seizure
there are changes in mood, sudden jerks of muscular activity, an aura (a peculiar sensation of
psychological change) like a bad smell, hallucination, bright lights, euphoria. Nature of the aura depends
on the starting focus.
Tonic –Colonic Phases:
Beginning – muscles contract, arms outstretch rigidly, involuntary cry, rigid posture for 15 seconds
End – muscles tremble, jerk convulsively, eyes roll, face is contorted, sweating and salivation, after 30
seconds breathing begins again and muscles relax. Exhausted sleep.
Cause some level of brain damage due to muffled respiration.
Petit Mal (absence seizure)
Vacant look, blinking repeatedly, unresponsive.
Can occur up to 100 times a day. They can be disruptive to normal activities. Often go undiagnosed. Usually halt in adolescence.
Bilateral symmetry according to a 3 second cycle.
Causes of Siezures:
Scaring of tissue caused by stroke, injury, growing tumor. Alcohol or barbiturate withdrawl.
-Almost half of seizure patients will have hippocampus damage.
A single episode of status epilepticus (during which the patient experiences a series of seizures without
regaining consciousness) causes excessive gluatamate release during.
Thus, NMDA receptors are involved because:
1) NMDA receptors control calcium channels. Alchohol blocks NMDA. Long term suppression of NMDA
receptors (abuse of alch) causes supersenstivity (up-regulation)
When an alchoholic suddenly stops drinking, the receptor rebounds. Which causes seizures.
Strokes – sudden onset disorder that causes brain damage.
Hemorrhagic stroke – bleeding within the brain. Caused when a vessel ruptures due to high blood
Ischemic stroke – caused by a disruption of the blood supply to the brain. Causes:
1) Thrombus – blood clot (air bubble, tumor, fat)
2) Embolus, carried through the blood stream (material)
3) Arteriosclerosis - thickening of the cerebral wall.
Stroke Induced release of glutamate kills neurons
-K/Na pump channels stop functioning due to the lack of oxygen and glucose.
The neuron membrane depolarises which causes excessive glutamate release.
-Excessive glutamate triggers influx of Na and Ca ions by way of NMDA receptors. Causes it to
propagate to the next cell.
Damaged mitochondria produce free radicals.