OMM® Question of the Day: Enlarged prostate

Explore the role of sympathetic innervation in urinary symptoms and how manipulation of specific spinal levels can alleviate prostate-related issues.

An 85-year-old man presents to the clinic complaining of needing to urinate over five times a night for the past month. He is frustrated because despite feeling an intense need to go, it takes some time for the stream to begin. Physical exam shows normal external genitalia and digital rectal exam reveals a smooth, rubbery, enlarged prostate. Urinalysis results are shown below:

Based on the most likely diagnosis, manipulation to which of the following levels would affect sympathetic innervation to the affected organ?

A. T1-T4

B. T1-T5

C. S2-S4

D. T5-T8E. T11-L2

Scroll down for the correct answer!

The correct answer to today’s USMLE® Step 1 Question is…

E. T11-L2

Before we get to the Main Explanation, let’s look at the incorrect answer explanations. Skip to the bottom if you want to see the correct answer right away!

Incorrect answer explanations

A. T1-T4

Incorrect: Spinal cord segments T1-T4 are associated with sympathetic innervation of head and neck.

B. T1-T5

Incorrect:  Spinal cord segments T1-T5 are associated with sympathetic innervation of the heart.

C. S2-S4

Incorrect: Spinal cord segments S2-S4 are associated with parasympathetic, not sympathetic, innervation to the lower ureter, bladder, urethra, uterus, prostate, genitalia, descending colon, sigmoid colon, and rectum.

D. T5-T8

Incorrect: Spinal cord segments T5-T9 are associated with sympathetic innervation to the stomach, gallbladder, spleen, pancreas, and liver.

Main Explanation

Specific levels of the thoracolumbar spine correspond to the sympathetic innervation of organs. The prostate receives sympathetic innervation from spinal levels T11-L2, therefore this would be the correct choice. Through viscerosomatic and somatovisceral reflexes, manipulation of the muscles, bones, and tissues of the spine can affect the sympathetic and parasympathetic innervation to organs. By manipulating T11-L2, sympathetic outflow to the prostate will be normalized and can help his urinary symptoms. The prostate has an abundance of alpha-1 receptors; when these receptors are stimulated smooth muscle contracts in the prostate and bladder neck leading to symptoms of urinary obstruction, like hesitancy and urgency. By affecting the sympathetic outflow, these receptors can potentially become less stimulated leading to relaxation of the smooth muscle and alleviating the urinary obstruction. Although OMM can be used, this patient will likely require pharmacological treatment with tamsulosin, an alpha-1 antagonist.

Major Takeaway

Sympathetic fibers from T12-L2 affect not only the prostate but the bladder as well. Sympathetic innervation to the prostate causes smooth muscle to contract via alpha-1 receptors, leading to urinary obstructive symptoms.

References

• Moore, R. A., Waheed, A., & Burns, B. (2019). Rule of Nines. In StatPearls [Internet]. StatPearls Publishing.
• Monafo, W. W. (1996). Initial management of burns. New England Journal of Medicine, 335(21), 1581-1586.
• Wachtel, T. L., Berry, C. C., Wachtel, E. E., & Frank, H. A. (2000). The inter-rater reliability of estimating the size of burns from various burn area chart drawings. Burns, 26(2), 156-170.

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