PH2113 - Neuropharmacology 6

Question 1

What is a cerebral ventricle?

Answer 1

Membrane bound cavity in the brain lined with ependymal cells

Question 2

What are the cerebral ventricles filled with?

Answer 2

Cerebrospinal fluid at 10 mmHg pressure

Question 3

Where is cerebrospinal fluid produced?

Answer 3

Walls of lateral ventricle and third ventricle by choroid plexus

Question 4

How does cerebrospinal fluid circulate?

Answer 4

From the lateral ventricle to the third ventricle then to the fourth ventricle via the cerebral aqueduct
Cerebrospinal fluid flows into the spinal canal and subarachnoid space, then drains back to cerebral blood via arachnoid sinus or via spinal nerve roots or via olfactory tracts

Question 5

What is ondansetron?

Answer 5

Highly specific and selective serotonin 5-HT3 receptor antagonist

Ondansetron is used to prevent nausea and vomiting caused by cancer chemotherapy, radiation therapy, and surgery.

Question 6

Where are 5-HT3 receptors located?

Answer 6

Nerve terminals of the vagus in the periphery

Centrally in the chemoreceptor trigger zone

Question 7

What is the indications of Ondansetron?

Answer 7

Prevents nausea and vomiting caused by cancer chemotherapy, radiation therapy or surgery

Question 8

What is Ondansetron not used for?

Answer 8

Vomiting caused by motion sickness

- controlled by limbic system

Question 9

What is the structure of the choroid plexus?

Answer 9

Epithelial cells present in each of the four ventricles surrounding ventricle-associated blood capillaries

Possesses tight junctions limiting passive protein transport from blood to intra-ventricular space containing CSF
- not as restrictive as BBB

Question 10

What is the function of the choroid plexus?

Answer 10

Secretes cerebrospinal fluid
Possesses transport systems
- secretes proteins
- pre-albumin
- removes waste products
Blood-CSF Barrier

Question 11

What is the dura?

Answer 11

Tissue that keeps the spinal fluid around the spinal cord and spinal nerves

Question 12

When are epidural injections useful?

Answer 12

During childbirth
- including caeareans
During some types of surgery
- pelvic area
- legs
Steroid
- treat back or leg pain caused by sciatica or prolapsed

Question 13

What are the advantages of using epidurals for surgery?

Answer 13

Remain awake and responsive
Less nausea and vomiting
Quicker recovery afterwards
Reduce risk of DVT

Question 14

What are the challenges with epidural injections?

Answer 14

Still outside the cerebrospinal fluid with a barrier remaining to cross (DURA)

Question 15

What are the advantages with epidural injections?

Answer 15

Not violated cerebrospinal fluid space and reduced risk of infection
- less technically demanding

Question 16

What are the indications for intrathecal injections?

Answer 16

Chronic spasticity due to injury, multiple sclerosis and cerebral palsy
- baclofen
Management of cancer, chronic non-malignant or neuropathic pain
- morphine
Chemotherapy lymphomatous meningitis
- methotrexate
- cytarabine
Antibiotic treatment adjuvant to systemic therapy in bacterial meningitis and other infections of the central nervous system
- gentamicin

Question 17

What are the challenges of intrathecal injections?

Answer 17

More highly skilled procedure

Greater risk of infection

Question 18

What are the advantages of intrathecal injections?

Answer 18

Bypasses dura

- accessing directly the cerebrospinal fluid

Question 19

What is the Ommaya reservoir?

Answer 19

Intra-ventricular catheter system that can be used for the aspiration of cerebrospinal fluid or for the delivery of drugs into the cerebrospinal fluid
- chemotherapy
Reservoir implanted subcutaneously with catheter in one lateral ventricle attached to a reservoir

Question 20

What is the function of the Ommaya reservoir?

Answer 20

Used to treat brain tumours, leukemia, lymphoma

In the palliative care of terminal cancer, a Ommaya reservoir can be inserted for intracerebroventricular (ICV) injection of morphine