Posterior Fossa Craniotomies Flashcards
Advantages of sitting position for posterior fossa craniotomies include improved drainage of blood and CSF out of the surgical site, enhanced venous drainage which helps reduce venous bleeding, easy ventilation, and patients’ head can be kept at exactly midline. Which of the following are included in the
disadvantages of sitting position?
● A. Possible air embolism
● B. Fatigue of operator’s hand and risk of postoperative hematoma at the surgical site
● C. Possible brachial plexus injury and mid cervical quadriplegia
● D. Extent of postoperative pneumocephalus is more pronounced and venous pooling of blood in the lower extremities
● E. All of the above
E. All of the above
Air embolism is suspected in any operative case in which the surgical site is higher than the heart. Transesophageal echocardiography and precordial Doppler ultrasound are the tests to see air embolism in heart. Following are included in the treatment of air embolism except?
● A. The site of air entry is found and occluded and the patient’s head is lowered if at all possible
● B. Jugular venous compression or aspiration of air from right atrium
● C. Nitrous oxide is given if it is not being used
● D. Patient is ventilated with 100% oxygen
● E. Pressors volume expanders are used to maintain blood pressure
C. Nitrous oxide is given if it is not being used
Lateral oblique position is also known as Park Bench position. Axillary roll is used for the down-side arm and upper arm is supported on pillows or towels. Adhesive tape is used to pull down the upper shoulder. Thorax is usually elevated to what degrees in such cases?
● A. 10 to 15 degrees
● B. 20 to 25 degrees
● C. 30 to 35 degrees
● D. 40 to 45 degrees
● E. It is kept flat
A. 10 to 15 degrees
Indications for paramedian suboccipital craniectomy include all of the following except?
● A. Access to CPA lesions like vestibular schwannoma or for microvascular decompression
● B. For lesions in the cerebellar hemisphere
● C. For access to the posterior communicating artery aneurysms
● D. For access to the vertebral artery for aneurysms or for vertebral endarterectomy
● E. For access to the anterolateral brain stem
C. For access to the posterior communicating artery aneurysms
Which of the following statements are correct regarding access to CP angle lesions through paramedian incision?
● A. A slightly curved retromastoid incision is made 5 mm medial to the mastoid notch
● B. 5–4-6 incision (5 mm medial to mastoid notch, 6 cm above notch, and 4 cm below notch) is made for approach to the fifth nerve like in microvascular decompression
● C. 5–5-5 incision (5 mm medial to mastoid notch, 5 cm above notch, and 5 cm below notch) is used for microvascular decompression for hemifacial spasm or for small vestibular schwannoma
● D. 5–4-6 incision (5 mm medial to notch, 4 cm above notch, and 6 cm below notch) is used for glossopharyngeal neuralgia
● E. All of the above
E. All of the above
For microvascular decompression, a craniectomy of 2 cm is used in the angle between transverse sinus and sigmoid sinus while for small tumors (< 2.5 cm), a 4-cm craniectomy is used in the same space. What are the boundaries of craniectomy for large tumors?
● A. Transverse sinus superiorly
● B. Foramen magnum inferiorly
● C. Sigmoid sinus laterally
● D. Midline medially
● E. All of the above
E. All of the above
Burr hole for placement of emergency ventriculostomy is done at Frazier point which is 3 to 4 cm from midline and how much distance from the inion?
● A. 6 to 7 cm above the inion
● B. 3 to 4 cm above the inion
● C. 6 to 7 cm above the inion in adults, while 3 to 4 cm above inion in children
● D. 8 cm above inion in adults, while 5 cm above inion in children
● E. None of the above
C. 6 to 7 cm above the inion in adults, while 3 to 4 cm above inion in children
For midline suboccipital craniectomies, Y-shaped durotomy is often used and craniectomy is done with no intention of replacing the bone. What is the advantage of not replacing the bone at this location?
● A. It is cumbersome to place bone here
● B. It can dip into cerebellum when the patient lies on head
● C. If there is postoperative swelling, the inelastic bone will cause more pressure to be transmitted to the brainstem
● D. There is more chance of postoperative infection if bone is placed
● E. None of the above
C. If there is postoperative swelling, the inelastic bone will cause more pressure to be transmitted to the brainstem
The two main approaches for the 4th ventricle are transvermian approach and telovelar approach. Following statements are correct regarding these approaches except?
● A. Transvermian approach gives wider and slightly more rostral exposure than telovelar approach
● B. The risks of caudal vermis syndrome, cerebellar mutism, and injury to caudate nucleus are more in case of transvermian approach
● C. No nerve tissue is harmed in case of telovelar approach
● D. Telovelar approach causes decreased access to the lateral recess of the 4th ventricle
● E. Telovelar approach provides narrower corridor as compared to transvermian approach
D. Telovelar approach causes decreased access to the lateral recess of the 4th ventricle
The causes of CSF fistula are abnormal CSF hydrodynamics, poor wound closure, or subarachnoid scarring. The treatment of CSF fistula includes elevation of the head of bed, lumbar
subarachnoid drainage, reinforcement of skin incisions, or surgical correction. What are the treatment options for suboccipital pseudomeningocele?
● A. Noninvasive measures like expectant management, fluid restriction, head wrapping, keeping head of bed elevated, and acetazolamide use
● B. Percutaneous aspiration
● C. Direct surgical exploration with multilayer closure
● D. Lumbar drainage or ventricular drainage
● E. All of the above
E. All of the above
