A 25-year-old man with no significant past medical history is brought in by ambulance after a witnessed seizure at home. On physical exam, temperature is 102.3 deg F (39.1 deg C), blood pressure is 90/62 mmHg, pulse is 118/min, and respirations are 25/min. He is unable to touch his chin to his chest and spontaneously flexes his hips with passive neck flexion. Appropriate empiric treatment is begun. CT head is unremarkable, and a lumbar puncture sample is obtained. Gram stain of the cerebrospinal fluid (CSF) reveals gram-positive diplococci. Which of the following would you expect to see on CSF studies?

Elevated opening pressure, elevated protein, low glucose

Elevated opening pressure, elevated protein, normal glucose

Normal opening pressure, normal protein, normal glucose

Elevated opening pressure, elevated protein, elevated glucose

Normal opening pressure, elevated protein, normal glucose

A 52-year-old woman is accompanied by her husband to the emergency department with a severe occipital headache that started suddenly an hour ago. She is drowsy but able to answer the physician's questions. She describes it as the worst headache she has ever had, 9/10 in intensity. The husband says it was initially localized to the occiput but has now spread all over her head and she also complained of a generalized heaviness. She took an ibuprofen without experiencing any relief. She also complains of blurry vision and nausea and had 1 episode of vomiting. She denies a recent history of fever, chills, numbness, or seizures. Her past medical history is significant for hypertension controlled with lisinopril and metoprolol. On examination, she is drowsy but oriented. Papilledema is seen on ophthalmoscopy. Neck flexion is difficult and painful. The rest of the exam is unremarkable. Her blood pressure is 160/100 mm Hg, heart rate is 100/min, and temperature is 37.0°C (98.6°F). The ECG, cardiac enzymes, and laboratory studies are normal. Lumbar puncture results are as follows: Opening pressure 210 mm H2O RBC 50/mm3, numbers steady over 4 test tubes Cell count 5/mm3 Glucose 60 mg/dL Proteins 100 mg/dL The patient is admitted to the ICU for further management. Which of the following is the most likely pathophysiology based on her history and CSF findings?

Rupture of the communicating branches of the cerebral arteries

Viral infection of the brain parenchyma

Bacterial infection of the meninges

A 56-year-old male with a history of hepatitis C cirrhosis status post TIPS procedure is brought in by his wife to the emergency department because he has been acting disoriented, slurring his speech, and sleeping throughout the day. On arrival the patient is afebrile and his vital signs are pulse is 87/min, blood pressure is 137/93 mmHg, and respirations are 12/min with shallow breaths. Examination reveals a jaundiced male who appears older than stated age. Abdominal exam is positive for a fluid wave and shifting dullness to percussion. You note enlarged breasts, decreased facial hair, 3+ patellar reflexes bilaterally, and the following in the upper extremity (Image A). Paracentesis reveals ascitic fluid with neutrophil counts of < 100 cells/mcL. Serum creatinine is 1.0 and BUN is 15. Which of the following is the next best step in management?

Administer neomycin and glucose

IV albumin and antibiotic therapy with cefotaxime

Administer rifaximin and glucose

A 62-year-old man is brought to the emergency department after his wife found him unresponsive 1 hour ago. He had fallen from a flight of stairs the previous evening. Four years ago, he underwent a mitral valve replacement. He has hypertension and coronary artery disease. Current medications include aspirin, warfarin, enalapril, metoprolol, and atorvastatin. On arrival, he is unconscious. His temperature is 37.3°C (99.1°F), pulse is 59/min, respirations are 7/min and irregular, and blood pressure is 200/102 mm Hg. The right pupil is 5 mm and fixed. The left pupil is 4 mm and reactive to light. There is extension of the extremities to painful stimuli. The lungs are clear to auscultation. Cardiac examination shows a systolic click. The abdomen is soft and nontender. He is intubated and mechanically ventilated. A mannitol infusion is begun. A noncontrast CT scan of the brain shows a 6-cm subdural hematoma on the right side with an 18-mm midline shift. Which of the following is the most likely early sequela of this patient's current condition?

Right eye esotropia and elevation

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

Hydrocephalus diagnosis and shunt procedures for USMLE Step 2 CK: High-Yield Surgery Lessons

🧠 Pathophysiology - Brain Fluid Fiasco

Non-communicating (Obstructive): Blockage within the ventricular system prevents CSF from reaching the subarachnoid space.
- Causes: Aqueductal stenosis, tumors, intraventricular hemorrhage.
Communicating: Impaired CSF reabsorption by arachnoid granulations; ventricles are in communication with the subarachnoid space.
- Causes: Post-meningitis scarring, subarachnoid hemorrhage (SAH) debris.

⭐ Acute hydrocephalus after SAH is often obstructive (blood clots), while chronic is communicating (impaired absorption).

Hydrocephalus: Communicating vs. Non-communicating Causes

🧠 Head Full of Trouble

Presentation varies dramatically by age, primarily due to skull suture fusion status. ↑ ICP drives symptoms.

Feature	Infants (Open Sutures)	Children & Adults (Fused Sutures)
Head/ICP	Macrocephaly, bulging fontanelles	Headache (worse AM), papilledema
Eyes	"Sunsetting" eyes (tonic downward gaze)	6th nerve palsy (lateral gaze deficit)
Function	Irritability, poor feeding, developmental delay	Gait instability, cognitive decline, lethargy

-   📌 **Hakim's Triad: "Wet, Wobbly, Wacky"**
-   Urinary incontinence, magnetic gait, dementia.

⭐ In NPH, gait disturbance is typically the first symptom to appear and the most likely to improve with CSF shunting.

Infant with hydrocephalus: clinical signs

🧠 Diagnosis - Spotting the Swell

Imaging (CT/MRI): First-line test shows ventriculomegaly.
- For Normal Pressure Hydrocephalus (NPH), calculate the Evan's Index.
- Evan's Index > 0.3 is diagnostic for NPH.
  - $Evan's\ Index = \frac{Maximal\ Frontal\ Horn\ Width}{Maximal\ Internal\ Skull\ Diameter}$
NPH Confirmation:
- 💡 High-Volume Lumbar Puncture (LP Tap Test): Remove 30-50 mL CSF.
- Transient improvement in gait/cognition predicts positive shunt response.

⭐ In NPH, ventriculomegaly is disproportionately large compared to sulcal effacement, distinguishing it from hydrocephalus ex vacuo (brain atrophy).

Axial and Coronal MRI: Ventriculomegaly in NPH

🧠 Management - Draining the Brain

Ventriculoperitoneal (VP) Shunt: The primary surgical treatment for most hydrocephalus types.
- A catheter drains excess CSF from a lateral ventricle through a one-way valve.
- The distal catheter is tunneled subcutaneously to the peritoneal cavity for CSF absorption.

Ventriculoperitoneal (VP) Shunt Placement in a Child

Endoscopic Third Ventriculostomy (ETV):
- Alternative for obstructive hydrocephalus (e.g., aqueductal stenosis).
- Creates a bypass by fenestrating the floor of the third ventricle, allowing CSF to flow directly into the interpeduncular cistern.

⭐ Shunt malfunction (obstruction, infection) is the most common complication. Infection risk is highest 1-3 months post-op, typically with Staphylococcus epidermidis.

⚠️ Complications - When Shunts Go South

Infection: Most common within 6 months post-op.
- Causative organisms: Staphylococcus epidermidis (biofilm), S. aureus.
- Presents with fever, ↑ICP signs, shunt site erythema.
Malfunction/Obstruction: Most common cause of shunt failure.
- Proximal (ventricular catheter) or distal (peritoneal) blockage.
- Presents with recurrent hydrocephalus symptoms.
Overdrainage: Excessive CSF removal.
- Leads to slit ventricle syndrome (postural headaches).
- Risk of subdural hematomas from torn bridging veins.

⭐ Shunt infection within the first few months is almost always due to skin flora (S. epidermidis) introduced during surgery.

⚡ Biggest Takeaways

Normal Pressure Hydrocephalus (NPH) presents with the classic triad: "wet, wobbly, and wacky" (incontinence, ataxia, dementia).

CT/MRI is the initial diagnostic test, showing ventriculomegaly. NPH diagnosis is supported by improvement after a high-volume LP.

Ventriculoperitoneal (VP) shunt is the definitive treatment for most forms of hydrocephalus.

Key shunt complications include infection (S. epidermidis), obstruction, and overdrainage (subdural hematoma).

In infants, suspect hydrocephalus with a rapidly increasing head circumference, bulging fontanelle, and sunset eyes.

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