Dr. Natalie Chang: Neurology Q&A Session

Introduction

• Dr. Natalie Chang: Neurologist and Assistant Professor of Clinical Neurology.
• Purpose: Answer internet questions about the nervous system.

Headaches

• Brain itself has no sensory nerves, hence no pain receptors.
• Headaches are due to pain fibers in other structures (meninges, blood vessels, head/neck muscles).

Funny Bone

• Misnamed: Actually the ulnar nerve, which runs around the medial epicondyle of the upper arm.
• Named from a 19th-century joke; bone called the humerus (sounds like "humorous").

Limbs Falling Asleep

• Term: Paresthesias (pins and needles sensation).
• Cause: Compression of a peripheral nerve halts electrical signal transmission to the brain.
• Relief: When compression stops, signals resume, causing the pins and needles sensation.

General Anesthesia

• Enables pain-free surgery; has five components:
  1. Unconsciousness
  2. Amnesia (not remembering the procedure)
  3. Pain control
  4. Maintaining bodily functions
  5. Muscle relaxation and paralysis
• Importance: Provides a safe and controlled environment for surgery.

Sympathetic vs. Parasympathetic Nervous System

• Sympathetic: "Fight or flight" response, increases heart rate, dilates muscles' arteries, reduces blood to GI system.
• Parasympathetic: "Rest and digest" or "feed and breed", aids in digestion and reproduction.

Anxiety and the Nervous System

• Anxiety symptoms (fast heart rate, trouble breathing) are fight or flight responses.
• Chronic anxiety means these responses are constantly active, causing mental, physical, and emotional stress.

Nerve Impulse Speed

• Action potentials can travel up to 100 meters per second (224 mph).
• Myelinated nerves: Insulation speeds up impulse travel via saltatory conduction.

Body Movement

• Controlled via the corticospinal tract.
• Brain's motor cortex sends signals to muscles via the spinal cord, crossing at the medulla.

Itching

• Defensive mechanism to remove irritants (e.g., mosquitoes).
• Similar to pain but less intense.

Tickling

• Functional neuroimaging: Activates somatosensory cortex and anterior cingulate cortex (touch and emotion).
• Laughter: Possible social bonding or submission mechanism.

Central vs. Peripheral Nervous System

• Central Nervous System (CNS): Brain and spinal cord.
• Peripheral Nervous System (PNS): Nerves outside the skull and spinal column.

Acupuncture

• Effective for chronic pain management according to clinical trials.

Purpose of Pain

• Defense mechanism to prevent further injury (e.g., stepping on a nail).

Nerve Regeneration

• Peripheral nerves can regenerate; immune system clears debris before new growth starts.

Reflex Testing

• Example: Knee-jerk reflex checks motor and sensory neuron integrity.
• Absent reflex: Possible lower motor neuron issue.
• Overactive reflex: Possible upper motor neuron issue.

Pain Tolerance

• Influenced by various factors: trauma history, sleep, gender, age, exercise, social support.

Carpal Tunnel Syndrome

• Compression of the median nerve in the wrist's carpal tunnel due to repetitive stress (e.g., typing, cooking).

Local Anesthesia

• Drugs like lidocaine block voltage-gated sodium ion channels, halting nerve signal transmission.

Brain Zaps

• Sensation of electrical shocks in the head, often after stopping medications (antidepressants, ecstasy, benzodiazepines).
• Cause: Possible changes in neurotransmitter levels.

Tooth Nerves and Toothaches

• Teeth are crucial and permanent; nerves in teeth provide quick alerts to avoid severe damage or infection.

Conclusion

• Dr. Chang answered diverse questions about the nervous system, providing insights into common neurological issues and mechanisms.