Nerve hyperplasia: a unique feature of ketamine cystitis

Area of Science:

• Urology
• Neuropathology
• Pain Management

Background:

• Ketamine abuse is linked to urological symptoms like pain, frequency, and urgency.
• Severe cases present with bladder pain, contraction, and urothelial damage.
• Neuropathological features in ketamine cystitis are not well understood.

Purpose of the Study:

• To investigate the unusual neuropathological features in ketamine cystitis using immunohistology.
• To understand the neurogenic mechanisms underlying pain in ketamine cystitis.

Main Methods:

• Immunohistochemistry was used to examine bladder tissue samples from patients with ketamine cystitis.
• Analysis focused on nerve fiber and fascicle changes, including expression of neurofilament protein (NFP), S100, and nerve growth factor receptor (NGFR).
• Comparison with other painful bladder conditions was performed.

Main Results:

• Lamina propria showed abundant neurofilament protein (NFP+) nerve fibers in all cases.
• Peripheral nerve fascicle hyperplasia, resembling Morton's neuroma, was prominent in most patients (20/21).
• Increased NGFR expression was observed in remaining urothelium, indicating potential urothelial involvement in pain.

Conclusions:

• Histological findings, particularly peripheral nerve fascicle hyperplasia, are distinguishing features of ketamine cystitis.
• The pain in ketamine cystitis is mediated by a specific neurogenic mechanism.
• These findings may also implicate the urothelium in the pain pathway and suggest a need for pain management strategies.