Here’s another USMLE® Step 2 CK Question of the Day! Today’s case involves a 32-year-old man who fell from a building. He did not suffer loss of consciousness. The patient has 2+ triceps and brachioradialis reflexes and 5/5 strength of the upper extremities bilaterally. The patient is unable to move the bilateral lower extremities. Which of the following reflects the most likely level of spinal injury? Can you figure it out?
A 32-year-old man is brought to the emergency department after falling two stories while washing windows on scaffolding. Per paramedics, the patient fell directly on his back, was helmeted, and did not suffer the loss of consciousness. On arrival, temperature is 98.6°F (37°C), pulse is 45/min, respirations are 22/min, blood pressure is 178/65 mmHg, and O2 saturation is 95% on room air. The patient’s primary survey is intact. The patient’s secondary survey is notable for bruising and tenderness over the cervical and thoracic spine. A neurological examination demonstrates loss of sensation starting below the xiphoid process. The patient has 2+ triceps and brachioradialis reflexes and 5/5 strength of the upper extremities bilaterally. The patient is unable to move the bilateral lower extremities. Which of the following reflects the most likely level of spinal injury?
A. T7
B. T4
C. C2
D. C4
E. T10
The correct answer to today’s USMLE® Step 2 CK Question is…
A. T7
Before we get to the Main Explanation, let’s see why the answer wasn’t B, C, D, or E. Skip to the bottom if you want to see the correct answer right away!
Incorrect answer explanations
B. T4
Incorrect: A spinal lesion at T4 would present with loss of sensation below the nipple line; this patient has preserved sensation at this dermatome.
C. C2
Incorrect: A spinal lesion at C2 would result in loss of sensation below the posterior half of the skull; injuries to this spinal level are often lethal due to damage to brainstem structures.
D. C4
Incorrect: Injury to the C4 level would result in loss of sensation below the collar line and possible diaphragmatic dysfunction since this spinal cord level helps innervate the diaphragm.
E. T10
Incorrect: A spinal cord lesion at T10 would result in loss of sensation starting at the level of the umbilicus.
Main Explanation
This patient presents for trauma evaluation after sustaining an injury to the spine. The neurologic examination is consistent with preserved sensation and motor strength above the level of T7, which is best approximated at the xiphoid process level.
Pathologies that affect the spinal cord are diverse and include trauma, ischemia, infection, autoimmune conditions, neoplasm, and hereditary-degenerative diseases. Compressive etiologies (e.g. those resulting in direct physical impingement on the spinal cord) include tumors, spinal epidural abscesses, hematomas, herniated disks, or bony disease. Spinal cord transection can also result from direct trauma such as stab wounds, gunshot wounds, or extreme shearing forces. Ischemia, particularly from the anterior or posterior spinal arteries, may also result in injury to the spinal cord.
Regardless of the etiology, the level of injury can be determined via a focused neurological assessment, including sensation testing, motor function testing, and reflex testing. The absence of sensation below a particular dermatome in conjunction with correlating motor and reflex deficits can indicate the level of a lesion.
Major Takeaway
Pathologies that affect the spinal cord are diverse and include trauma, ischemia, infection, autoimmune conditions, neoplasm, and hereditary-degenerative diseases. A detailed neurologic examination can often elucidate the level of spinal injury.
References
Kaplan AI, Krishnan C, Deshpande DM, et al. Diagnosis and management of acute myelopathies. Neurologist 2005; 11:2.
McDonald JW, Sadowsky C. Spinal-cord injury. Lancet. 2002 Feb 2;359(9304):417-25. doi: 10.1016/S0140-6736(02)07603-1. PMID: 11844532.
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