A 25-year-old man comes to the physician for severe back pain. He describes the pain as shooting and stabbing. On a 10-point scale, he rates the pain as a 9 to 10. The pain started after he lifted a heavy box at work; he works at a supermarket and recently switched from being a cashier to a storekeeper. The patient appears to be in severe distress. Vital signs are within normal limits. On physical examination, the spine is nontender without paravertebral muscle spasms. Range of motion is normal. A straight-leg raise test is negative. After the physical examination has been completed, the patient asks for a letter to his employer attesting to his inability to work as a storekeeper. Which of the following is the most appropriate response?

I understand that you are uncomfortable, but the findings do not match the severity of your symptoms. Let's talk about the recent changes at your job.

“Yes. Since work may worsen your condition, I would prefer that you stay home a few days. I will write a letter to your employer to explain the situation.”

You say you are in severe pain. However, the physical examination findings do not suggest a physical problem that can be addressed with medications or surgery. I'd like to meet on a regular basis to see how you're doing.

The physical exam findings do not match your symptoms, which suggests a psychological problem. I would be happy to refer you to a mental health professional.

The physical exam findings suggest a psychological rather than a physical problem. But there is a good chance that we can address it with cognitive-behavioral therapy.

A 26-year-old G1P0 woman at 40 weeks estimated gestational age presents after experiencing labor pains. Pregnancy has been uncomplicated so far. Rupture of membranes occurs, and a transvaginal delivery is performed under epidural anesthesia, and the baby is delivered alive and healthy. The patient voids a few hours after the delivery and complains of mild irritation at the injection site on her back. On the second day, she complains of a severe headache over the back of her head. The headache is associated with pain and stiffness in the neck. Her headache is aggravated by sitting up or standing and relieved by lying down. The pain is relieved slightly by acetaminophen and ibuprofen. The patient is afebrile. Her vital signs include: pulse 100/min, respiratory rate 18/min, and blood pressure 128/84 mm Hg. Which of the following statements is the most accurate regarding this patient’s condition?

This patient’s condition can resolve on its own

A blockage of CSF is the cause of this patient’s headache

An infection is present at the epidural injection site

Excessive bed rest will worsen this patient’s condition

Immediate intervention is required

A 77-year-old man with a history of hypertension and a 46 pack-year smoking history presents to the emergency department from an extended care facility with acute onset of headache, nausea, vomiting, and neck pain which started 6 hours ago and has persisted since. He is alert, but his baseline level of consciousness is slightly diminished per the nursing home staff. His temperature is 99.0°F (37.2°C), blood pressure is 164/94 mmHg, pulse is 90/min, respirations are 16/min, and oxygen saturation is 98% on room air. The patient's neurological exam is unremarkable with cranial nerves II-XII grossly intact and with stable gait with a walker. He is immediately sent for a head CT which is normal. What is the most appropriate next step in management?

Ibuprofen, acetaminophen, metoclopramide, and diphenhydramine

A 56-year-old woman presents with sudden-onset severe headache, nausea, vomiting, and neck pain for the past 90 minutes. She describes her headache as a ‘thunderclap’, followed quickly by severe neck pain and stiffness, nausea and vomiting. She denies any loss of consciousness, seizure, or similar symptoms in the past. Her past medical history is significant for an episode 6 months ago where she suddenly had trouble putting weight on her right leg, which resolved within hours. The patient denies any history of smoking, alcohol or recreational drug use. On physical examination, the patient has significant nuchal rigidity. Her muscle strength in the lower extremities is 4/5 on the right and 5/5 on the left. The remainder of the physical examination is unremarkable. A noncontrast CT scan of the head is normal. Which of the following is the next best step in the management of this patient?

Diffusion-weighted magnetic resonance imaging of the brain

Placement of a ventriculoperitoneal (VP) shunt

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 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 48-year-old woman undergoes awake craniotomy for resection of a left frontal glioma near Broca's area. Intraoperatively, cortical mapping identifies eloquent tissue, but the tumor extends into functionally critical regions. The surgeon achieves 70% resection when the patient develops expressive aphasia during mapping. Frozen section shows low-grade astrocytoma. The family previously expressed desire for maximal resection. Evaluate the intraoperative decision-making.

Stop resection to preserve language function

Use awake testing to define exact limits of safe resection

Obtain family consultation intraoperatively about acceptable deficits

Convert to asleep anesthesia and use anatomic landmarks for resection

Continue resection since low-grade tumors justify aggressive surgery

Lumbar puncture technique and indications — USMLE Lesson

💉 Why We Tap

LP is performed for both diagnostic and therapeutic reasons.

Diagnostic (CSF Analysis & Pressure)
- Infection: Suspected meningitis or encephalitis.
- Hemorrhage: Suspected subarachnoid hemorrhage (SAH) with a negative head CT.
- Inflammation: Multiple sclerosis (oligoclonal bands), Guillain-Barré syndrome (albuminocytologic dissociation).
- Malignancy: CNS lymphoma, leptomeningeal metastases.
- Pressure: Measure opening pressure (e.g., idiopathic intracranial hypertension [IIH]).
Therapeutic
- Relieve ↑ intracranial pressure (e.g., large volume tap in IIH).
- Administer intrathecal medications (e.g., chemotherapy, anesthetics, antibiotics).

⭐ In suspected SAH with a negative non-contrast head CT, an LP is the definitive next step to check for xanthochromia or RBCs.

⚠️ Clinical Correlations - Danger Zones

The primary risk of LP is iatrogenic cerebral herniation. Always assess for contraindications before proceeding.

Absolute Contraindications	Relative Contraindications
• Infection at puncture site	• Coagulopathy (Platelets < 50,000/μL, INR > 1.5)
• Signs of ↑ ICP / mass lesion	• Severe spinal deformity
• Suspected spinal epidural abscess	• Brain abscess (risk of seeding)

💉 The Needle's Path

Positioning: Lateral decubitus (fetal position) or sitting upright, maximally flexed to open interspinous spaces.
Landmark: A line connecting the superior iliac crests crosses the L4 spinous process.
Insertion: L3-L4 or L4-L5 interspace. Needle with bevel up (parallel to dural fibers), angled slightly cephalad.

Lumbar Puncture Needle Path in Spinal Column

⭐ A distinct "pop" is felt as the needle pierces the ligamentum flavum and a second, finer pop for the dura-arachnoid membrane.

📌 Skinny Suzan Is Always Laying Down Asleep: Skin, Subcutaneous, Supraspinous, Interspinous, Ligamentum flavum, Dura, Arachnoid.

🧪 Diagnosis - Decoding the Fluid

Analyze CSF via 4 tubes: 1) Cell count/differential, 2) Gram stain/culture, 3) Glucose/protein, 4) Special tests (e.g., oligoclonal bands, VDRL). Classic findings differentiate key CNS pathologies.

Condition	OP (cmH₂O)	WBC/μL (Diff)	Glucose (mg/dL)	Protein (mg/dL)
Bacterial	↑↑ (>25)	↑↑ (>1000, PMNs)	↓↓ (<40)	↑↑ (>200)
Viral	N/↑ (<25)	↑ (<1000, Lymphs)	Normal	N/↑ (<150)
Fungal/TB	↑	↑ (<500, Lymphs)	↓ (<45)	↑ (>150)
SAH	↑	↑↑ RBCs	Normal	↑

🤕 Complications - The Aftermath

Post-LP Headache: Most common. Orthostatic (worse upright, better supine) from CSF leakage.
Infection: Iatrogenic meningitis (rare).
Bleeding: Epidural/subdural hematoma, esp. with coagulopathy.
⚠️ Herniation: Fatal risk if ↑ICP with a mass lesion.

⭐ Treat post-LP headache with bed rest, hydration, and caffeine; consider an epidural blood patch for severe, refractory cases.

⚡ Biggest Takeaways

Insert needle at the L3/L4 or L4/L5 interspace (level of iliac crests); the spinal cord ends at L1-L2 in adults.

Absolute contraindication: Signs of increased ICP (e.g., papilledema); risk of cerebral herniation. Get a CT head first if suspected.

Key indications: Suspected meningitis, subarachnoid hemorrhage (SAH), Guillain-Barré syndrome, and multiple sclerosis.

Needle pierces ligaments (ligamentum flavum gives a "pop"), dura, and arachnoid mater.

Use the lateral decubitus position to accurately measure opening pressure.

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