Neurogenic Bladder on Cystography

Neurogenic bladder is bladder dysfunction due to lesions of the nervous system and not an appropriate imaging diagnosis. The appearance of the bladder on cystography depends on the level of injury:

• Detrusor hyperreflexia: Caused by suprapontine lesions. The micturition reflex is intact but the detrusors are spastic. The bladder is persistently smooth and rounded due to uninhibited detrusor contractions. There are prominent interureteric indentations during voiding. Trabeculations may be seen in longstanding disease.
• Detrusor hyperreflexia with detrusor-sphincter dyssynergia: Caused by spinal cord lesions above T12/conus medullaris. Bladder contracts with an open internal sphincter and closed external sphincter. The bladder neck dilates during contractions (open internal sphincter and closed external sphincter). The bladder itself is elongated and trabeculated ("pine cone," "pine tree," "fir tree," or "Christmas tree" bladder). Detrusor-sphincter dyssynergia is the most common cause of a dilated posterior urethra.
• Autonomous neurogenic bladder: Lesions of conus medullaris, cauda equina, sacral nerve roots, or peripheral nerves (e.g., diabetes, alcoholism, trauma). The end result is loss of sensation and loss of contraction. Loss of contraction means that the normal urethral resistance cannot be overcome and the bladder expands until the pressure is high enough to push urine through the urethra (overflow incontinence). The bladder contour is typically smooth, but the pine tree bladder can also be seen.

References

• Gamut H-113. in Gamuts in Radiology - Reeder and Felson - 4th ed (Springer, 2003).
• Zagoria RJ and Tung GA (1997). Chapter 6. in Genitourinary Radiology: The Requisites.