1. ETV overview: {image source}

2. ETV endoscopic view: {image source}

3. ETV steps: 

4. A common reason for failure of ETV is not perforating the liliequist membrane, which underlies the floor of the third ventricle {image source} 

(s- sellar, m- mesencephalic, d-diencephalic)

5. In the olden days, people used to do frontal craniotomies to fenestrate the lamina terminalis for management of hydrocephalus. The idea is you generate a communication between the third ventricle and the cortical subarachnoid space, but it probably doesn't work-- in this series of 15 patients who got LT fenestrations during aneurysm surgery in an attempt to reduce the incidence of hydrocephalus, there was no evidence of free flow of omnipaque contrast between ventricles and basal cisterns (vs a + control who got ETV). 

6. Lamina terminalis anatomy: 

7. The lamina terminalis represents the most rostral part of the neural tube from which the CNS is derived. It contains the OVLT (organum vasculosum of the lamina terminalis), which is one of the circumventricular organs. These neurons respond to the osmolality of the blood, and project to neurons that control the release of ADH. The OVLT is also stimulated by angiotensin II, as well. 

8. Thoughts about precedex/dexmedetomidine 

- Central a-2 agonist 

- Less risk of delirium upon awakening from anesthesia (good for people who have a record of this n the past) 

- Can induce bradycardia, esp in kids (a2 agonism...) 

- No risk of respiratory depression

- Can take a while for people to wake up 

- Expensive!!

9. Thoughts about propofol:

- Fast on fast off IF you give a bolus, but if you run a drip for say a 6 or 8 hour case, the levels increase in the blood and levels build up in the fat, and you can be sitting on the slow end of the elimination curve. 

10. Thoughts about the volatile inhaled agents

- Increase ICP at full dose, but less of an effect at lower doses

- Often used in combo with propofol in neuro cases as propofol alone may not be sufficient to induce deep anesthesia.