What is the diagnosis for a patient with dulled sensation of ejaculation, altered bladder sensation, and a feeling of rectal fullness without pain or incontinence, presenting with a sensation of something sitting in the rectum?

Differential Diagnosis: Pudendal Neuropathy vs. Incomplete Cauda Equina Syndrome

This presentation most likely represents pudendal neuropathy, given the isolated sensory changes in the pudendal distribution (ejaculation, bladder, rectal sensation) without motor deficits, incontinence, or bilateral radicular symptoms that would indicate cauda equina syndrome. 1, 2

Primary Diagnostic Consideration: Pudendal Neuropathy

Pudendal neuropathy characteristically causes dulled or altered sensation in its three main branches: dorsal nerve (affecting ejaculatory sensation), perineal nerves (affecting bladder sensation), and inferior rectal nerves (affecting rectal sensation and fullness). 1, 3, 4

Key Supporting Features:

• The sensation of "something sitting in the rectum" without actual incontinence is consistent with pudendal nerve involvement affecting rectal sensory perception 1, 3
• Altered bladder sensation without incontinence suggests sensory rather than motor dysfunction, typical of pudendal neuropathy 1, 5
• Dulled ejaculatory sensation specifically points to dorsal penile/clitoral nerve involvement, a branch of the pudendal nerve 3, 6, 4
• Patients with pudendal neuropathy commonly describe symptoms as "pressure," "dulled sensation," or "discomfort" rather than pain 1, 7

Diagnostic Approach:

• Perform pinprick sensory testing at six specific sites in the pudendal territory (three branches bilaterally: dorsal nerve, perineal nerve, inferior rectal nerve), which diagnoses pudendal neuropathy in 92% of patients 5, 4
• Digital rectal examination may reveal pelvic floor muscle spasm 1
• Warm detection threshold (WDT) testing provides definitive diagnosis when combined with pinprick examination, showing abnormalities in 88-100% of pudendal neuropathy cases 5

Critical Red Flag Assessment: Rule Out Cauda Equina Syndrome

You must actively exclude incomplete cauda equina syndrome, as this presentation could represent early-stage disease requiring emergency intervention. 2

Red Flags That Would Indicate Cauda Equina (Currently ABSENT but must assess):

• Bilateral radiculopathy (bilateral leg pain, sensory disturbance, or motor weakness below the knee) - this is the most critical red flag 2
• Progressive neurological deficits in the lower extremities 2
• Bilateral motor weakness in legs 2
• New difficulties with micturition beyond just altered sensation 2

White Flags (Late Signs - If Present, Indicates Established Damage):

• Urinary retention or painless incontinence (90% sensitivity for established cauda equina) 2
• Complete perineal anesthesia rather than dulled sensation 2
• Fecal incontinence 2
• Patulous anus 2

If ANY red flags are present, obtain emergency MRI of the lumbosacral spine immediately, as cauda equina syndrome requires decompressive surgery within 12-72 hours to prevent permanent neurological damage. 2

Secondary Consideration: Chronic Prostatitis/Chronic Pelvic Pain Syndrome (CP/CPPS)

CP/CPPS overlaps significantly with pudendal neuropathy and may coexist 1:

• Pelvic pain or discomfort for at least 3 months in the perineum, suprapubic region, or tip of penis 1
• Pain exacerbated by urination or ejaculation 1
• Sense of incomplete bladder emptying 1
• Many patients describe "pressure" rather than pain 1

Immediate Clinical Actions

1. Check anal sphincter tone and lower extremity neuromuscular function during digital rectal examination 1
2. Perform pinprick sensory examination at all six pudendal nerve branches bilaterally 5, 4
3. Assess for bulbocavernosus reflex and voluntary rectal tone - normal findings effectively rule out cauda equina syndrome 2
4. Obtain urinalysis and urine culture 1
5. If any red flags present (especially bilateral radiculopathy or progressive leg weakness), obtain emergency MRI 2

Common Pitfalls to Avoid

• Do not wait for urinary retention or incontinence before considering cauda equina syndrome - these are late signs indicating irreversible damage 2
• Do not dismiss altered sensation as "functional" without performing systematic pinprick testing of the pudendal territory 5, 4
• Do not rely on CT imaging if cauda equina is suspected - it has only 6% sensitivity for neural compression; MRI is mandatory 2
• Unilateral pudendal neuropathy is common (38% of cases) and significantly impacts function even without bilateral involvement 8
• Sensory testing is subjective and subtle perineal sensory impairment is easily missed without systematic examination 2