A 68-year-old man is brought to the emergency department because of a severe headache, nausea, and vomiting for 30 minutes. Forty-five minutes ago, he fell and struck his head, resulting in loss of consciousness for 1 minute. After regaining consciousness, he felt well for 15 minutes before the headache began. On arrival, the patient becomes rigid and his eyes deviate to the right; he is incontinent of urine. Intravenous lorazepam is administered and the rigidity resolves. Which of the following is the most likely cause of the patient's condition?

Bleeding between dura mater and skull

Cerebrospinal fluid production/absorption mismatch

Acute insufficiency of cerebral blood flow

Four days after being hospitalized, intubated, and mechanically ventilated, a 30-year-old man has no cough response during tracheal suctioning. He was involved in a motor vehicle collision and was obtunded on arrival in the emergency department. The ventilator is at a FiO2 of 100%, tidal volume is 920 mL, and positive end-expiratory pressure is 5 cm H2O. He is currently receiving vasopressors. His vital signs are within normal limits. The pupils are dilated and nonreactive to light. Corneal, gag, and oculovestibular reflexes are absent. There is no facial or upper extremity response to painful stimuli; the lower extremities show a triple flexion response to painful stimuli. Serum concentrations of electrolytes, urea, creatinine, and glucose are within the reference range. Arterial blood gas shows: pH 7.45 pCO2 41 mm Hg pO2 99 mm Hg O2 saturation 99% Two days ago, a CT scan of the head showed a left intracerebral hemorrhage with mass effect. The apnea test is positive. There are no known family members, advanced directives, or individuals with power of attorney. Which of the following is the most appropriate next step in management?

Court order for further management

A six-month-old male presents to the pediatrician for a well-child visit. The patient’s mother is concerned about the patient’s vision because he often turns his head to the right. She has begun trying to correct the head turn and places him on his back with his head turned in the opposite direction to sleep, but she has not noticed any improvement. She is not certain about when the head turning began and denies any recent fever. She reports that the patient fell off the bed yesterday but was easily soothed afterwards. The patient is otherwise doing well and is beginning to try a variety of solid foods. The patient is sleeping well at night. He is beginning to babble and can sit with support. The patient was born at 37 weeks gestation via cesarean delivery for breech positioning. On physical exam, the patient’s head is turned to the right and tilted to the left. There is some minor bruising on the posterior aspect of the head and over the sternocleidomastoid. He has no ocular abnormalities and is able to focus on his mother from across the room. Which of the following is the best next step in management?

Reassurance and follow-up in one month

Which change in CSF production most directly affects intracranial pressure?

Decreased carbonic anhydrase activity

Decreased arachnoid granulation function

Increased choroid plexus blood flow

A 57-year-old man was brought into the emergency department unconscious 2 days ago. His friends who were with him at that time say he collapsed on the street. Upon arrival to the ED, he had a generalized tonic seizure. At that time, he was intubated and is being treated with diazepam and phenytoin. A noncontrast head CT revealed hemorrhages within the pons and cerebellum with a mass effect and tonsillar herniation. Today, his blood pressure is 110/65 mm Hg, heart rate is 65/min, respiratory rate is 12/min (intubated, ventilator settings: tidal volume (TV) 600 ml, positive end-expiratory pressure (PEEP) 5 cm H2O, and FiO2 40%), and temperature is 37.0°C (98.6°F). On physical examination, the patient is in a comatose state. Pupils are 4 mm bilaterally and unresponsive to light. Cornea reflexes are absent. Gag reflex and cough reflex are also absent. Which of the following is the next best step in the management of this patient?

Second opinion from a neurologist

Withdraw ventilation support and mark time of death

Repeat examination in several hours

A 48-year-old woman is brought to the emergency department because of a 1-hour history of sudden-onset headache associated with nausea and vomiting. The patient reports she was sitting at her desk when the headache began. The headache is global and radiates to her neck. She has hypertension. She has smoked one pack of cigarettes daily for the last 10 years. She drinks alcohol occasionally. Her father had a stroke at the age 58 years. Current medications include hydrochlorothiazide. She is in severe distress. She is alert and oriented to person, place, and time. Her temperature is 38.2°C (100.8°F), pulse is 89/min, respirations are 19/min, and blood pressure is 150/90 mm Hg. Cardiopulmonary examination shows no abnormalities. Cranial nerves II–XII are intact. She has no focal motor or sensory deficits. She flexes her hips and knees when her neck is flexed while lying in a supine position. A CT scan of the head is shown. Which of the following is the most appropriate intervention?

Administer intravenous alteplase

Administer intravenous vancomycin and ceftriaxone

Perform decompressive craniectomy

A 47-year-old man is admitted to the emergency room after a fight in which he was hit in the head with a hammer. The witnesses say that the patient initially lost consciousness, but regained consciousness by the time emergency services arrived. On admission, the patient complained of a diffuse headache. He opened his eyes spontaneously, was verbally responsive, albeit confused, and was able to follow commands. He could not elevate his left hand and leg. He did not remember the events prior to the loss of consciousness and had difficulty remembering information, such as the names of nurses or doctors. His airway was not compromised. The vital signs are as follows: blood pressure, 180/100 mm Hg; heart rate, 59/min; respiratory rate, 12/min; temperature 37.0℃ (98.6℉); and SaO2, 96% on room air. The examination revealed bruising in the right frontotemporal region. The pupils are round, equal, and show a poor response to light. The neurologic examination shows hyperreflexia and decreased power in the left upper and lower limbs. There is questionable nuchal rigidity, but no Kernig and Brudzinski signs. The CT scan is shown in the image. Which of the following options is recommended for this patient?

Surgical evacuation of the clots

Administration of levetiracetam

Administration of methylprednisolone

A 77-year-old man is brought to the emergency department by his wife because of headache, nausea, and vomiting for 24 hours. His wife says that over the past 2 weeks, he has been more irritable and has had trouble remembering to do routine errands. Two weeks ago, he fell during a skiing accident but did not lose consciousness. He has coronary artery disease and hypertension. He has smoked one pack of cigarettes daily for 50 years. He has had 2 glasses of wine daily since his retirement 10 years ago. Current medications include atenolol, enalapril, furosemide, atorvastatin, and aspirin. He appears acutely ill. He is oriented to person but not to place or time. His temperature is 37°C (98.6°F), pulse is 99/min, respirations are 16/min, and blood pressure is 160/90 mm Hg. During the examination, he is uncooperative and unable to answer questions. Deep tendon reflexes are 4+ on the left and 2+ on the right. Babinski's sign is present on the left. There is mild weakness of the left iliopsoas and hamstring muscles. A CT scan of the head without contrast shows a high-density, 15-mm crescentic collection across the right hemispheric convexity. Which of the following is the most appropriate next step in the management of this patient?

Recombinant tissue plasminogen activator administration

Obtain an Electroencephalography

Craniotomy indications and techniques Notes – USMLE Surgery

🧠 Clinical - Why Open the Box?

Craniotomy is indicated for accessing intracranial structures to treat pathology.

Tumor Resection:
- Primary (glioma) or metastatic brain tumors.
- Benign tumors (meningioma) causing mass effect.
Traumatic Brain Injury (TBI):
- Evacuation of space-occupying hematomas (epidural, subdural).
- Decompressive craniectomy for refractory intracranial pressure (↑ICP).
Vascular Lesions:
- Clipping of cerebral aneurysms.
- Resection of arteriovenous malformations (AVMs).
Infection:
- Drainage of brain abscesses or subdural empyema.

⭐ An epidural hematoma (EDH) with neurological decline, pupillary changes, or volume >30 cm³ requires emergent craniotomy and evacuation, especially following a "lucid interval."

🗺️ Anatomy - Skull's Surgical Atlas

Key Surgical Landmarks (Craniometric Points):

Pterion: "H"-shaped junction of frontal, parietal, temporal, & sphenoid bones; weakest point of the skull.
Bregma: Junction of coronal & sagittal sutures; site of anterior fontanelle.
Lambda: Junction of sagittal & lambdoid sutures; site of posterior fontanelle.
Asterion: Junction of lambdoid, occipitomastoid, & parietomastoid sutures; key for retrosigmoid approach.
Stephanion: Junction of coronal suture & superior temporal line.

Craniotomy Approaches and Skull Landmarks

Common Surgical Approaches & Targets:

Pterional: "Workhorse" approach for Circle of Willis aneurysms, suprasellar tumors.
Retrosigmoid/Suboccipital: Cerebellopontine Angle (CPA) tumors (e.g., acoustic neuroma).
Bifrontal: Anterior skull base tumors (e.g., olfactory groove meningioma).
Transsphenoidal: Pituitary adenomas (via nasal cavity).

⭐ Pterion fracture is a neurosurgical emergency. It can lacerate the underlying anterior division of the middle meningeal artery, leading to a life-threatening epidural hematoma.

🛠️ Clinical - The Neurosurgeon's Toolkit

A craniotomy is a surgical procedure where a bone flap is temporarily removed from the skull to access the brain.

Positioning: Patient's head is immobilized using a Mayfield clamp (3-pin skull fixation).
Access:
- An incision is made, and a scalp flap is reflected.
- Burr holes are drilled into the skull.
- A craniotome (foot-plated drill) connects the burr holes to create the bone flap.
Exposure & Closure:
- The dura mater is opened (C-shaped flap) and later closed (watertight).
- The bone flap is replaced using titanium plates and screws.

⭐ Pearl: The base of the C-shaped dural flap is typically oriented towards major venous sinuses (e.g., superior sagittal sinus) to preserve venous drainage and reduce bleeding risk.

⚠️ Complications - Post-Op Pitfalls

Immediate (Hours-Days)
- Hemorrhage (EDH, SDH, IPH): Presents with new focal deficits or ↓LOC. Requires urgent CT scan.
- Cerebral Edema: Worsening neuro status. Manage with steroids, osmotherapy.
- Ischemic Stroke: From direct vessel injury or vasospasm.
Early (Days-Weeks)
- CSF Leak: Clear rhinorrhea/otorrhea (test for β-2 transferrin), postural headache.
- Meningitis: Fever, nuchal rigidity, altered mental status.
- Seizures: Prophylaxis is common (e.g., levetiracetam).
- VTE (DVT/PE): High risk due to immobility.
Late (Weeks-Months)
- Hydrocephalus: Impaired CSF absorption/flow.
- Syndrome of the Trephined: Sunken flap with neuro decline; cranioplasty is curative.

⭐ Post-op fever workup: Rule out non-neuro causes first (wind, water, wound, walking, wonder drugs). If negative, consider meningitis/ventriculitis; obtain CSF if safe.

Post-craniotomy epidural hematoma: diagrams and CT scans

⚡ Biggest Takeaways

Craniotomy involves removing and replacing a bone flap for definitive treatment of tumors, hematomas, or vascular lesions.

Craniectomy is removal of the bone flap without immediate replacement, primarily for decompression in severe TBI or malignant stroke.

The pterional approach is a workhorse for anterior circulation aneurysms (e.g., ACoA, PCoA) and suprasellar tumors.

The suboccipital approach provides access to the posterior fossa (cerebellum, brainstem).

Major risks include post-operative hematoma, infection, seizures, and new neurological deficits.

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