Reflexic / Areflexic / Mixed Lesion bladder

Reflexic Bladder

The reflexic bladder is caused by an upper motor neurone injury. The reflexic bladder may have the following outcomes:

• Loss sensation of a full bladder or the ability to know when the bladder has emptied
• Loss of control of the ability to void or to prevent leaking
• Pelvic floor dysfunction secondary to muscle paralysis as well as hypertonicity
• Intact spinal reflexes coupled with the loss of descending inhibition. This causes the detrusor to reflexively contract spontaneously or with small bladder volumes. An overactive (hyperreflexic) detrusor results in reduced bladder capacity.
• Increased risk of Detrusor Sphincter Dyssynergia (DSD), where the detrusor muscle and urethral sphincter simultaneously contract due to loss of coordination between the central and peripheral nervous systems. DSD results in an increase in pressure within the bladder, which puts the upper renal tracts at risk of long-term complications.

The risks of the overactive bladder are:

• incomplete emptying
• ureteric reflux
• reduced capacity
• increased frequency
• incontinence
• increased risk of urinary tract infections
• high pressures within the upper renal tract

Areflexic Bladder

The areflexic bladder is caused by a lower motor neurone or cauda equina syndrome. The areflexic bladder may have the following outcomes:

• Loss sensation of a full bladder or the ability to know when the bladder has emptied
• Loss of control of the ability to void or to prevent leaking
• Pelvic floor dysfunction secondary to muscle paralysis
• Detrusor underactivity compromising bladder emptying
• Potential loss of sphincter muscle tone causing urinary leakage

The risks of the underactive bladder are:

• incomplete emptying
• bladder distension
• increased frequency
• incontinence
• increased risk of urinary tract infections

Manoeuvres that increase intraabdominal pressure such as a Valsalva manoeuvre (straining to empty the bladder and/or bowel), application of external pressure to the bladder (Credé manoeuvre), coughing and sneezing can increase the risk of:

• urinary and/or faecal leakage
• vaginal and/or rectal prolapse or haemorrhoids

Mixed Lesion Bladder

• Mixed level injuries around the conus medullaris (T10-L1) can show both signs of a reflexic and areflexic bladder.
• An individualised plan is required in these cases