Cauda equina syndrome

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Cauda equina syndrome

Nervous system

Autonomic nervous system disorders

Horner syndrome

Orthostatic hypotension


Cauda equina syndrome


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USMLE® Step 1 questions

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High Yield Notes

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Cauda equina syndrome

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USMLE® Step 1 style questions USMLE

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A 76-year-old man is brought to the emergency department to evaluate acute-on-chronic low back pain. Several years ago, the patient was diagnosed with prostate cancer, but he elected to forego treatment and was lost to follow-up. Today, the patient was brought in by family members after he could not get out of bed. The patient states, “I can’t lift my legs, and I woke up covered in my stool.” The patient has no other significant medical history or medication use. Temperature is 37.0 °C (98.6 °F), pulse is 105/min, respirations are 18/min, blood pressure is 176/65 mmHg, and O2 saturation is 97% on room air. Physical examination shows a cachectic male in moderate distress. The patient has diffuse lumbar spinal tenderness to palpation and 2/5 strength of the lower extremities bilaterally. The patient’s pelvic x-ray is demonstrated below. Which of the following additional clinical features most indicates this patient’s clinical condition?

Reproduced from: Wikipedia


Cauda equina syndrome is a condition caused by damage to the bundle of peripheral nerves protruding from the bottom of the spinal cord, called the cauda equina.

The latin words cauda equina mean horse’s tail, which is what early anatomists thought this nerve bundle looked like.

The spinal column is made of individual bones, called vertebrae.

Each vertebra is made of a large anterior portion called the body, and the posterior part called the vertebral arch.

The central cavity between the body and the arch is called the vertebral foramen.

Now the spinal column is made of 33 vertebrae: 7 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 4 coccygeal.

Other than C1 and C2, each two adjacent vertebrae are, separated by an intervertebral disc, which allows for a slight movement of the vertebrae, and acts as a shock absorber.

The sacral and coccygeal vertebrae are fused together to form the sacral bone and coccyx, or tailbone respectively.

Now if you cut the spinal column in half lengthwise you can see that all the vertebral foramina together form the vertebral, or the spinal canal, which is occupied by the spinal cord.

The spinal cord is connected to the brain and travels through the spinal canal to the second lumbar vertebra, where it ends in a cone, called conus medullaris.


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  3. "Pathophysiology of Disease: An Introduction to Clinical Medicine 8E" McGraw-Hill Education / Medical (2018)
  4. "CURRENT Medical Diagnosis and Treatment 2020" McGraw-Hill Education / Medical (2019)
  5. "Cauda Equina Syndrome" Journal of Pain & Palliative Care Pharmacotherapy (2014)
  6. "Cauda Equina Syndrome Due to Lumbar Disc Herniation: a Review of Literature" Folia Medica (2017)

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