Multiple Choice Questions on Brainstem Lesions for Neurosurgery
Question 1: Surgical Indications for Brainstem Cavernomas
A 42-year-old patient presents with a brainstem cavernoma that has hemorrhaged once, causing mild dysarthria that resolved. MRI shows a 1.2 cm pontine cavernoma with hemosiderin ring. What is the most appropriate management?
A) Immediate surgical resection
B) Stereotactic radiosurgery
C) Conservative management with serial imaging
D) Surgical resection after second symptomatic hemorrhage
Correct Answer: D
Explanation: After a second symptomatic hemorrhage, surgical resection of brainstem cavernomas is appropriate due to their potentially more aggressive course 1. Following a single hemorrhage, the indication for resection is weaker, as early postoperative morbidity for brainstem cavernomas affects almost 50% of cases 1. The risk of rebleeding after the first hemorrhage is 29.5% over 5 years 1. For asymptomatic brainstem cavernomas, conservative treatment is recommended, as the natural risk of death or non-fatal stroke is approximately 2.4% over 5 years, compared to 6% after surgical resection 1. Stereotactic radiosurgery may be considered for solitary cavernomas with prior symptomatic hemorrhage if located in eloquent areas with unacceptably high surgical risk, but the recommended prescription dose is between 11-13 Gy 1.
Question 2: Posterior Fossa Lesion Management
A 58-year-old presents with progressive headaches and subtle left leg weakness. MRI reveals a 4.1 x 2.3 cm petroclival meningioma with brainstem compression and fourth ventricular effacement. What is the most appropriate initial management?
A) Stereotactic radiosurgery
B) Observation with serial MRI
C) Surgical decompression via infratentorial craniectomy
D) Whole brain radiation therapy
Correct Answer: C
Explanation: Surgical decompression is the primary treatment modality for posterior fossa meningiomas with significant brain/brainstem compression, especially when there is evidence of neurological symptoms and tumor growth 2. Even when smaller than 3 cm, posterior fossa lesions with significant edema and incipient brainstem or fourth ventricular compression are better treated with open surgery rather than radiosurgery 3, 2. Resecting these lesions resolves mass effect more rapidly than radiosurgery 3. The subtle weakness in the left proximal leg muscles indicates early neurological compromise, further supporting the need for surgical intervention 2. Stereotactic radiosurgery is not appropriate as primary therapy due to the large tumor size (>3 cm) and significant mass effect requiring immediate decompression 2. The appropriate CPT code would be 61519 (Craniectomy for excision of brain tumor, infratentorial or posterior fossa; meningioma) 2.
Question 3: Cerebellar Hemorrhage with Brainstem Compression
A 65-year-old on warfarin presents with acute onset ataxia, vomiting, and declining consciousness (GCS 10). CT shows a 20 mL cerebellar hemorrhage with fourth ventricular compression and hydrocephalus. What is the most appropriate management?
A) External ventricular drainage alone
B) Medical management with ICP monitoring
C) Immediate surgical evacuation
D) Observation for 24-72 hours then reassess
Correct Answer: C
Explanation: Immediate surgical evacuation is recommended for patients with cerebellar hemorrhage who are deteriorating neurologically, have brainstem compression, hydrocephalus from ventricular obstruction, or cerebellar ICH volume ≥15 mL 4. This is a Class 1, Level B-NR recommendation from the American Heart Association 4. External ventricular drainage alone is potentially harmful and insufficient when there is brainstem compression 4. Surgery has been demonstrated to reduce mortality in cases of cerebellar hemorrhage 4. While a period of observation (24-72 hours) is recommended after initial stabilization for brainstem hemorrhage to improve decision-making quality, this patient is actively deteriorating with a large volume hemorrhage requiring urgent intervention 4. For rapidly deteriorating patients, craniotomy for hematoma evacuation may be considered as a life-saving measure 4.
Question 4: Multiple Middle Cranial Nerve Palsies
A 55-year-old presents with acute onset diplopia, facial numbness, and facial weakness on the right side. What is the most appropriate initial imaging study?
A) CT head without contrast
B) MRI head with contrast focusing on brainstem and skull base
C) CTA head and neck
D) FDG-PET/CT skull base to mid-thigh
Correct Answer: B
Explanation: MRI is useful for investigating potential brainstem, cavernous sinus, and leptomeningeal processes leading to multiple middle cranial nerve palsies 3. Imaging should focus on the brainstem, central skull base, and cavernous sinus 3. Pre- and postcontrast imaging provides the best opportunity to identify and characterize a lesion 3. Thin-section high-resolution techniques should be used extending through the course of the affected cranial nerves 3. DWI can be used to assess for acute brainstem infarction, with thin-section coronal DWI or thinner axial DWI improving sensitivity, as nearly 25% of acute brainstem infarcts are more easily seen on thin-cut coronal DWI compared with standard axial DWI 3. The combination of ipsilateral CN V and CN VII palsies raises concern for perineural spread of a tumor 3. Ischemic and hemorrhagic infarcts are the most frequent cause of acute brainstem syndromes 3.
Question 5: Cerebral Infarction with Swelling
A 52-year-old develops progressive somnolence 36 hours after a large MCA infarction. Exam shows ipsilateral pupillary dilation and worsening hemiparesis. What clinical signs indicate brainstem compression?
A) Contralateral Babinski sign and irregular breathing
B) Seizures and fluctuating consciousness
C) Hypertension and bradycardia
D) Hyperreflexia and clonus
Correct Answer: A
Explanation: A Babinski sign contralateral to the hemiparesis as a result of brainstem notching against the tentorium can occur, and abnormal respiratory patterns signaling lower brainstem dysfunction typically occur late in the course 3. The most commonly described signs in deterioration from hemispheric supratentorial infarction are ipsilateral pupillary dysfunction, varying degrees of mydriasis, and adduction paralysis 3. Worsening limb power progressing to extensor posturing of the extremity indicates deterioration 3. Abnormal respiratory patterns include central neurogenic hyperventilation, ataxic respiratory patterns, and periodic breathing 3. Clinicians should frequently monitor level of arousal and ipsilateral pupillary dilation in patients with supratentorial ischemic stroke at high risk for deterioration 3. Gradual development of midposition pupils and worsening of motor response may also indicate deterioration 3. Seizures are uncommon after a hemispheric infarct 3.