Fascial compartments

Fascial compartments US Medical PG Question 1: A 20-year-old woman is brought to the emergency department because of severe muscle soreness, nausea, and darkened urine for 2 days. The patient is on the college track team and has been training intensively for an upcoming event. One month ago, she had a urinary tract infection and was treated with nitrofurantoin. She appears healthy. Her temperature is 37°C (98.6°F), pulse is 64/min, and blood pressure is 110/70 mm Hg. Cardiopulmonary examination shows no abnormalities. The abdomen is soft and non-tender. There is diffuse muscle tenderness over the arms, legs, and back. Laboratory studies show: Hemoglobin 12.8 g/dL Leukocyte count 7,000/mm3 Platelet count 265,000/mm3 Serum Creatine kinase 22,000 U/L Lactate dehydrogenase 380 U/L Urine Blood 3+ Protein 1+ RBC negative WBC 1–2/hpf This patient is at increased risk for which of the following complications?

• A. Myocarditis
• B. Metabolic alkalosis
• C. Compartment syndrome
• D. Acute kidney injury (Correct Answer)
• E. Hemolytic anemia

Fascial compartments Explanation: ***Acute kidney injury*** - The patient's elevated **creatine kinase (CK)** of 22,000 U/L, muscle soreness, and dark urine (positive for blood but negative for red blood cells) are all indicative of **rhabdomyolysis**. - **Rhabdomyolysis** releases large amounts of myoglobin, which is nephrotoxic and can precipitate in the renal tubules, leading to **acute tubular necrosis** and subsequent acute kidney injury. *Myocarditis* - While CK elevations can be seen in myocarditis, this patient's presentation is dominated by **skeletal muscle symptoms** and a history of intense exercise. - There are no specific cardiac symptoms or signs (e.g., chest pain, arrhythmias) to suggest myocardial involvement. *Metabolic alkalosis* - Rhabdomyolysis typically causes **metabolic acidosis** due to the release of cellular contents, including phosphate and sulfate. - There is no clinical or lab evidence (e.g., vomiting, diuretic use) to suggest metabolic alkalosis. *Compartment syndrome* - **Compartment syndrome** involves increased pressure within a muscle compartment, leading to pain, pallor, paresthesia, pulselessness, and paralysis. - While rhabdomyolysis can occasionally lead to severe swelling that causes compartment syndrome, the diffuse muscle tenderness and absence of focal limb findings make it less likely as the primary direct complication. *Hemolytic anemia* - Though the urine is positive for blood and negative for RBCs, this is characteristic of **myoglobinuria**, not hemoglobinuria, which would indicate hemolytic anemia. - The patient's **hemoglobin** is normal (12.8 g/dL), and there are no other signs of hemolysis (e.g., jaundice, reticulocytosis).

Fascial compartments US Medical PG Question 2: An epidemiologist is evaluating the efficacy of Noxbinle in preventing HCC deaths at the population level. A clinical trial shows that over 5 years, the mortality rate from HCC was 25% in the control group and 15% in patients treated with Noxbinle 100 mg daily. Based on this data, how many patients need to be treated with Noxbinle 100 mg to prevent, on average, one death from HCC?

• A. 20
• B. 73
• C. 10 (Correct Answer)
• D. 50
• E. 100

Fascial compartments Explanation: ***10*** - The **number needed to treat (NNT)** is calculated by first finding the **absolute risk reduction (ARR)**. - **ARR** = Risk in control group - Risk in treatment group = 25% - 15% = **10%** (or 0.10). - **NNT = 1 / ARR** = 1 / 0.10 = **10 patients**. - This means that **10 patients must be treated with Noxbinle to prevent one death from HCC** over 5 years. *20* - This would result from an ARR of 5% (1/0.05 = 20), which is not supported by the data. - May arise from miscalculating the risk difference or incorrectly halving the actual ARR. *73* - This value does not correspond to any standard calculation of NNT from the given mortality rates. - May result from confusion with other epidemiological measures or calculation error. *50* - This would correspond to an ARR of 2% (1/0.02 = 50), which significantly underestimates the actual risk reduction. - Could result from incorrectly calculating the difference as a proportion rather than absolute percentage points. *100* - This would correspond to an ARR of 1% (1/0.01 = 100), grossly underestimating the treatment benefit. - May result from confusing ARR with relative risk reduction or other calculation errors.

Fascial compartments US Medical PG Question 3: Three days after undergoing laparoscopic colectomy, a 67-year-old man reports swelling and pain in his right leg. He was diagnosed with colon cancer 1 month ago. His temperature is 38.5°C (101.3°F). Physical examination shows swelling of the right leg from the ankle to the thigh. There is no erythema or rash. Which of the following is likely to be most helpful in establishing the diagnosis?

• A. D-dimer level
• B. Compression ultrasonography (Correct Answer)
• C. CT pulmonary angiography
• D. Transthoracic echocardiography
• E. Blood cultures

Fascial compartments Explanation: ***Compression ultrasonography*** - This patient's presentation with **unilateral leg swelling and pain** after surgery, especially given his recent **colon cancer diagnosis** (a hypercoagulable state), is highly suspicious for a **deep vein thrombosis (DVT)**. - **Compression ultrasonography** is the gold standard, non-invasive imaging modality for diagnosing DVT, allowing direct visualization of thrombi and assessing venous compressibility. *D-dimer level* - While a **positive D-dimer** indicates recent or ongoing clot formation, it is **non-specific** and can be elevated in many conditions, including surgery, cancer, and infection. - A normal D-dimer can rule out DVT in low-probability patients, but a high D-dimer in a high-probability patient (like this case) requires further imaging for confirmation, making it less definitive than ultrasound. *CT pulmonary angiography* - This imaging is used to diagnose a **pulmonary embolism (PE)**, which is a complication of DVT, but the primary symptoms here are localized to the leg. - While PE is a concern, diagnosing the source (DVT) in the leg is the immediate priority for treatment and prevention of future complications. *Transthoracic echocardiography* - **Echocardiography** evaluates cardiac structure and function and can sometimes detect large clots in the right heart leading to PE, but it is not the primary diagnostic tool for DVT in the leg. - It would be done if signs of cardiac strain or shunting associated with acute PE were prominent, which is not the case here. *Blood cultures* - **Blood cultures** are used to diagnose **bacteremia or sepsis**, which might explain a fever, but the prominent, unilateral leg swelling and pain are not typical for a primary infectious cause in the leg without local signs of cellulitis or abscess. - While a low-grade fever is present, the absence of erythema or rash makes a primary infectious etiology less likely than DVT given the risk factors.

Fascial compartments US Medical PG Question 4: A 35-year-old man is referred to a physical therapist due to limitation of movement in the wrist and fingers of his left hand. He cannot hold objects or perform daily activities with his left hand. He broke his left arm at the humerus one month ago. The break was simple and treatment involved a cast for one month. Then he lost his health insurance and could not return for follow up. Only after removing the cast did he notice the movement issues in his left hand and wrist. His past medical history is otherwise insignificant, and vital signs are within normal limits. On examination, the patient’s left hand is pale and flexed in a claw-like position. It is firm and tender to palpation. Right radial pulse is 2+ and left radial pulse is 1+. The patient is unable to actively extend his fingers and wrist, and passive extension is difficult and painful. Which of the following is a proper treatment for the presented patient?

• A. Surgical release (Correct Answer)
• B. Botulinum toxin injections
• C. Collagenase injections
• D. Needle fasciotomy
• E. Corticosteroid injections

Fascial compartments Explanation: ***Surgical release*** - The patient presents with classic signs of **established Volkmann's ischemic contracture** (claw-like hand, firm fibrotic tissue, limited movement, decreased radial pulse), which is the end-stage result of untreated compartment syndrome that occurred during fracture healing. - Since this is **chronic contracture (one month post-injury)**, the appropriate surgical treatment involves **reconstructive procedures** such as muscle slide operations, tendon lengthening, tendon transfers, neurolysis, or in severe cases, free functional muscle transfer to restore hand function. - Emergency fasciotomy would have been appropriate for **acute compartment syndrome** (within 6-8 hours of onset), but at this stage, the treatment focuses on releasing fibrotic tissue and restoring function through reconstructive surgery. *Botulinum toxin injections* - **Botulinum toxin** is used to relax spastic muscles in neurological conditions (e.g., cerebral palsy, stroke), but it does not address the underlying **ischemic fibrosis and muscle necrosis** of Volkmann's contracture. - It would not improve the structural contracture or restore blood flow in this patient. *Collagenase injections* - **Collagenase injections** are used for localized fascial contractures like Dupuytren's contracture, where enzymatic breakdown of collagen cords can restore finger extension. - They are ineffective for **Volkmann's contracture**, which involves widespread ischemic muscle necrosis, fibrosis, and nerve damage requiring surgical reconstruction. *Needle fasciotomy* - **Needle fasciotomy** is a minimally invasive technique for Dupuytren's contracture, involving percutaneous disruption of fascial cords. - It is not suitable for **Volkmann's contracture**, which requires extensive surgical release of fibrotic muscle compartments, possible tendon transfers, and neurolysis—procedures that cannot be accomplished with needle techniques. *Corticosteroid injections* - **Corticosteroids** reduce inflammation in conditions like tenosynovitis or trigger finger. - They would not address the **ischemic muscle necrosis and fibrotic contracture** in Volkmann's contracture and could potentially delay appropriate surgical treatment.

Fascial compartments US Medical PG Question 5: A 31-year-old man presents to the Emergency Department with severe left leg pain and paresthesias 4 hours after his leg got trapped by the closing door of a bus. Initially, he had a mild pain which gradually increased to unbearable levels. Past medical history is noncontributory. In the Emergency Department, his blood pressure is 130/80 mm Hg, heart rate is 87/min, respiratory rate is 14/min, and temperature is 36.8℃ (98.2℉). On physical exam, his left calf is firm and severely tender on palpation. The patient cannot actively dorsiflex his left foot, and passive dorsiflexion is limited. Posterior tibial and dorsalis pedis pulses are 2+ in the right leg and 1+ in the left leg. Axial load does not increase the pain. Which of the following is the best next step in the management of this patient?

• A. Lower limb CT scan
• B. Lower limb ultrasound
• C. Splinting and limb rest
• D. Fasciotomy (Correct Answer)
• E. Lower limb X-ray in two projections

Fascial compartments Explanation: ***Fasciotomy*** - The patient presents with classic signs and symptoms of **acute compartment syndrome**, including unrelieved pain by analgesics, paresthesias, pain with passive stretching, and a tense compartment due to the bus door trauma. - **Fasciotomy** is the definitive and urgent treatment to relieve pressure within the muscle compartments, prevent muscle ischemia, and avoid permanent nerve damage or limb loss. *Lower limb CT scan* - A **CT scan** is primarily used to evaluate bony structures and soft tissue injuries but is not the most immediate or definitive diagnostic tool for acute compartment syndrome. - Delaying **fasciotomy** for imaging in a clear case of compartment syndrome can lead to irreversible damage. *Lower limb ultrasound* - **Ultrasound** can assess vascular flow and some soft tissue aspects but is not accurate or rapid enough for diagnosing compartment syndrome. - It would not provide the necessary information to guide urgent surgical intervention. *Splinting and limb rest* - This approach is appropriate for fractures or soft tissue injuries without compartment syndrome; however, in acute compartment syndrome, **splinting or limb rest** will worsen the condition. - **Immobilization** and elevation are contraindicated as they can further decrease blood flow and increase compartment pressure. *Lower limb X-ray in two projections* - An **X-ray** is useful for ruling out fractures but will not provide information about compartment pressure or muscle viability. - While a fracture can sometimes cause compartment syndrome, the immediate concern here is the compartment syndrome itself, for which **X-rays** are not diagnostic.

Fascial compartments US Medical PG Question 6: A 28-year-old male presents to his primary care physician with complaints of intermittent abdominal pain and alternating bouts of constipation and diarrhea. His medical chart is not significant for any past medical problems or prior surgeries. He is not prescribed any current medications. Which of the following questions would be the most useful next question in eliciting further history from this patient?

• A. "Does the diarrhea typically precede the constipation, or vice-versa?"
• B. "Is the diarrhea foul-smelling?"
• C. "Please rate your abdominal pain on a scale of 1-10, with 10 being the worst pain of your life"
• D. "Are the symptoms worse in the morning or at night?"
• E. "Can you tell me more about the symptoms you have been experiencing?" (Correct Answer)

Fascial compartments Explanation: ***Can you tell me more about the symptoms you have been experiencing?*** - This **open-ended question** encourages the patient to provide a **comprehensive narrative** of their symptoms, including details about onset, frequency, duration, alleviating/aggravating factors, and associated symptoms, which is crucial for diagnosis. - In a patient presenting with vague, intermittent symptoms like alternating constipation and diarrhea, allowing them to elaborate freely can reveal important clues that might not be captured by more targeted questions. *Does the diarrhea typically precede the constipation, or vice-versa?* - While knowing the sequence of symptoms can be helpful in understanding the **pattern of bowel dysfunction**, it is a very specific question that might overlook other important aspects of the patient's experience. - It prematurely narrows the focus without first obtaining a broad understanding of the patient's overall symptomatic picture. *Is the diarrhea foul-smelling?* - Foul-smelling diarrhea can indicate **malabsorption** or **bacterial overgrowth**, which are important to consider in some gastrointestinal conditions. - However, this is a **specific symptom inquiry** that should follow a more general exploration of the patient's symptoms, as it may not be relevant if other crucial details are missed. *Please rate your abdominal pain on a scale of 1-10, with 10 being the worst pain of your life* - Quantifying pain intensity is useful for assessing the **severity of discomfort** and monitoring changes over time. - However, for a patient with intermittent rather than acute, severe pain, understanding the **character, location, and triggers** of the pain is often more diagnostically valuable than just a numerical rating initially. *Are the symptoms worse in the morning or at night?* - Diurnal variation can be relevant in certain conditions, such as inflammatory bowel diseases where nocturnal symptoms might be more concerning, or functional disorders whose symptoms might be stress-related. - This is another **specific question** that should come after gathering a more complete initial picture of the patient's symptoms to ensure no key information is overlooked.

Fascial compartments US Medical PG Question 7: A 48-year-old male presents to his primary care provider with a two-week history of low back pain and left leg pain. He reports that his symptoms started while he was working at his job as a construction worker. He has since experienced intermittent achy pain over his lumbar spine. He has also noticed pain radiating into his left leg and weakness in left ankle dorsiflexion. On exam, he demonstrates the following findings on strength testing of the left leg: 5/5 in knee extension, 4/5 in ankle dorsiflexion, 4/5 in great toe extension, 5/5 in ankle plantarflexion, and 5/5 in great toe flexion. The patellar reflexes are 5/5 bilaterally. He is able to toe walk but has difficulty with heel walking. Weakness in which of the following compartments of the leg is most likely causing this patient’s foot drop?

• A. Lateral compartment
• B. Superficial posterior compartment
• C. Deep posterior compartment
• D. Anterior compartment (Correct Answer)
• E. Medial compartment

Fascial compartments Explanation: ***Anterior compartment*** - Weakness in **ankle dorsiflexion** and **great toe extension**, coupled with difficulty **heel walking**, indicates a foot drop due to dysfunction of muscles in the anterior compartment, such as the **tibialis anterior**, **extensor hallucis longus**, and **extensor digitorum longus**. - These muscles are primarily innervated by the **deep fibular nerve**, which is susceptible to compression from conditions like **lumbar radiculopathy** (L4-L5 nerve root involvement). *Lateral compartment* - Muscles in the lateral compartment (**fibularis longus** and **brevis**) are responsible for **eversion** of the foot. - Weakness in this compartment would manifest as difficulty everting the foot, not primarily ankle dorsiflexion or great toe extension deficits. *Superficial posterior compartment* - This compartment contains muscles like the **gastrocnemius** and **soleus**, which are primarily responsible for **ankle plantarflexion**. - The patient exhibits 5/5 strength in ankle plantarflexion and is able to toe walk, indicating these muscles are functioning well. *Deep posterior compartment* - Muscles in the deep posterior compartment (**tibialis posterior**, **flexor digitorum longus**, **flexor hallucis longus**) are involved in **inversion** and **toe flexion**. - The patient has 5/5 strength in great toe flexion, suggesting intact function of these muscles, and his primary deficit is in dorsiflexion. *Medial compartment* - There is no distinct "medial compartment" of the leg in the anatomical sense comparable to the other listed compartments; rather, various muscles contribute to medial actions. - The symptoms described specifically point to weakness in dorsiflexion and toe extension, localizing the problem to the anterior compartment.

Fascial compartments US Medical PG Question 8: A 23-year-old woman presents to the emergency department with an acute exacerbation of her 3-month history of low back and right leg pain. She says she has had similar symptoms in the past, but this time the pain was so excruciating, it took her breath away. She describes the pain as severe, shock-like, and localized to her lower back and radiating straight down the back of her right thigh and to her calf, stopping at the ankle. Her pain is worse in the morning, and, sometimes, the pain wakes her up at night with severe buttock and posterior thigh pain but walking actually makes the pain subside somewhat. The patient reports no smoking history or alcohol or drug use. She has been working casually as a waitress and does find bending over tables a strain. She is afebrile, and her vital signs are within normal limits. On physical examination, her left straight leg raise test is severely limited and reproduces her buttock pain at 20° of hip flexion. Pain is worsened by the addition of ankle dorsiflexion. The sensation is intact. Her L4 and L5 reflexes are normal, but her S1 reflex is absent on the right side. A CT of the lumbar spine shows an L5–S1 disc protrusion with right S1 nerve root compression. Which of the following muscle-nerve complexes is involved in producing an S1 reflex?

• A. Adductors-obturator nerve
• B. Gastrocnemius/soleus-tibial nerve (Correct Answer)
• C. Sartorius-femoral nerve
• D. Tibialis posterior-tibial nerve
• E. Quadriceps femoris-femoral nerve

Fascial compartments Explanation: ***Gastrocnemius/soleus-tibial nerve*** - The S1 reflex (also known as the **Achilles reflex**) tests the integrity of the **S1 nerve root**. - This reflex arc involves the **gastrocnemius and soleus muscles**, which are innervated by the **tibial nerve** (derived primarily from S1). *Adductors-obturator nerve* - The **adductor muscles** of the thigh are primarily innervated by the **obturator nerve** (L2-L4). - This complex is not involved in generating the **Achilles reflex**. *Sartorius-femoral nerve* - The **sartorius muscle** is innervated by the **femoral nerve** (L2-L4). - This muscle and nerve are not part of the **S1 reflex arc**. *Tibialis posterior-tibial nerve* - The **tibialis posterior muscle** is innervated by the **tibial nerve** (L4-S3), but its primary role is in ankle inversion and plantarflexion, not the main component of the **Achilles reflex**. - While the tibial nerve is involved in the S1 reflex, the **gastrocnemius and soleus** are the primary muscles for this reflex. *Quadriceps femoris-femoral nerve* - The **quadriceps femoris muscle** is responsible for the **patellar reflex** (knee jerk reflex), which tests the integrity of the **L3-L4 nerve roots**. - It is innervated by the **femoral nerve** and is not involved in the **S1 reflex**.

Fascial compartments US Medical PG Question 9: A 68-year-old man is brought to the emergency department by ambulance after he was found to be altered at home. Specifically, his wife says that he fell and was unable to get back up while walking to bed. When she approached him, she found that he was unable to move his left leg. His past medical history is significant for hypertension, atrial fibrillation, and diabetes. In addition, he has a 20-pack-year smoking history. On presentation, he is found to still have difficulty moving his left leg though motor function in his left arm is completely intact. The cause of this patient's symptoms most likely occurred in an artery supplying which of the following brain regions?

• A. Motor cortex (ACA) (Correct Answer)
• B. Cerebellum (PICA/SCA)
• C. Occipital cortex (PCA)
• D. Brainstem (Vertebrobasilar)
• E. Motor cortex (MCA)

Fascial compartments Explanation: ***Motor cortex (ACA)*** - The patient's inability to move his **left leg** while his **left arm** remains intact points to an injury in the **right cerebral hemisphere** affecting the leg area of the motor cortex. - The leg area of the **primary motor cortex** is primarily supplied by the **anterior cerebral artery (ACA)**, making an ACA stroke the most likely cause. *Motor cortex (MCA)* - The **middle cerebral artery (MCA)** primarily supplies the motor cortex areas responsible for the **face and arm**, not typically isolated leg weakness. - If the MCA were affected, you would expect to see involvement of the face and/or arm on the contralateral side in addition to leg weakness. *Brainstem (Vertebrobasilar)* - A **brainstem stroke** would likely present with more widespread neurological deficits, including **cranial nerve palsies**, ataxia, or altered consciousness. - Isolated contralateral leg weakness without arm involvement is not characteristic of a brainstem lesion. *Cerebellum (PICA/SCA)* - The **cerebellum** is primarily involved in **coordination and balance**, not direct motor strength. - A cerebellar stroke would present with symptoms like **ataxia**, dysarthria, or nystagmus, not isolated paralysis. *Occipital cortex (PCA)* - The **occipital cortex** is primarily responsible for **vision**. - A posterior cerebral artery (PCA) stroke would typically cause **visual field defects** (e.g., contralateral homonymous hemianopia) rather than motor weakness.

Fascial compartments US Medical PG Question 10: An investigator is studying the effects of an antihypertensive drug during pregnancy. Follow-up studies show that the drug can adversely affect differentiation of the ureteric bud into its direct derivatives in fetuses exposed during the first trimester. Which of the following structures is most likely to develop incorrectly in the affected fetus?

• A. Collecting ducts (Correct Answer)
• B. Proximal convoluted tubule
• C. Loop of Henle
• D. Bladder
• E. Distal convoluted tubule

Fascial compartments Explanation: ***Collecting ducts*** - The **ureteric bud** is an outgrowth of the **mesonephric (Wolffian) duct** that directly gives rise to the **collecting ducts**, minor and major calyces, renal pelvis, and ureter. - An adverse effect on the differentiation of the ureteric bud during the first trimester would directly impact the development of these structures, potentially leading to renal dysplasia or collecting system abnormalities. - **Clinical correlation**: ACE inhibitors and ARBs are contraindicated in pregnancy due to their teratogenic effects on fetal renal development. *Proximal convoluted tubule* - The **proximal convoluted tubule** develops from the **metanephric mesenchyme**, not from the ureteric bud. - This structure is part of the nephron proper, which forms when the metanephric mesenchyme is induced by the ureteric bud to differentiate. *Loop of Henle* - The **loop of Henle** also develops from the **metanephric mesenchyme**. - While its formation depends on inductive signals from the ureteric bud, it is not a direct derivative of the ureteric bud itself. *Bladder* - The **bladder** develops from the **urogenital sinus**, which is derived from the ventral part of the **cloaca** after partitioning by the urorectal septum. - Its development is distinct from the derivatives of the ureteric bud, though they are functionally connected. *Distal convoluted tubule* - The **distal convoluted tubule** develops from the **metanephric mesenchyme**. - It is a component of the nephron and connects to the collecting duct but is not a direct derivative of the ureteric bud.

Fascial compartments Flashcard 1 of 7

Question: In an anterior urethral injury, blood accumulates in the _____, and can spread into the perineal space

Answer: scrotum

Fascial compartments Flashcard 2 of 7

Question: Structures of the _____ system include the hippocampus, amygdala, fornix, mammillary bodies, and cingulate gyrus

Answer: limbic

Fascial compartments Flashcard 3 of 7

Question: The _____ artery is commonly injured due a knee dislocation

Answer: popliteal

Fascial compartments Flashcard 4 of 7

Question: Volkmanns ischemic contracture is a result of scarring / stiffening / shortening of the _____ muscles

Answer: forearm

Fascial compartments Flashcard 5 of 7

Question: In Iliotibial Band Syndrome, pain develops secondary to friction of the iliotibial band against the _____

Answer: lateral femoral epicondyle

Fascial compartments Flashcard 6 of 7

Question: The valsalva maneuver increases intraabdominal and intrathoracic pressure predominantly by recruiting the _____ muscle

Answer: rectus abdominis

Fascial compartments Flashcard 7 of 7

Question: The most common site for limb compartment syndrome is the _____ of the leg

Answer: anterior compartment