A 45-year-old man comes to the emergency department due to urinary incontinence. He was diagnosed with multiple sclerosis a year ago after he developed transient acute vision loss in his right eye. A few weeks ago, he began having difficulty with his balance and had several episodes of urinary incontinence. The patient's walking has improved since, but he continues to urinate involuntarily. He has noticed increasing urinary frequency and cannot control the urge to urinate. His vital signs are normal. On examination, the patient has mild spastic paraparesis with increased reflexes in the lower extremities; bilateral Babinski sign; and a thoracic sensory level to pain, temperature, and vibration. An MRI of the spine reveals a new demyelinating lesion in the mid-thoracic spinal cord. Which of the following abnormalities will most likely be found on this patient's urodynamic studies?
This patient has urinary frequency and urge incontinence in the setting of an overactive or spastic bladder due to the presence of an upper motor neuron lesion in the spinal cord. Patients with multiple sclerosis often develop a spastic bladder a few weeks after developing an acute lesion of the spinal cord. Urodynamic studies show little or no residual urine after emptying as bladder contractility is normal but distensibility is poor. The bladder does not distend/relax properly due to loss of descending inhibitory control from the upper motor neuron.
(Choice B) This patient will have premature, as opposed to delayed, emptying due to his bladder overactivity. Delayed bladder emptying is more likely to occur in patients with diminished bladder tone.
(Choices C and E) Reduced urine flow and elevated urethral pressure indicate a mechanical obstruction (eg, enlarged prostate, urethral stricture) along the urinary tract.
(Choice D) Flaccid bladder typically occurs in the setting of lower motor neuron lesions (eg, cauda equina syndrome). A patient with a flaccid bladder will have a large residual volume of urine after attempted emptying and will typically experience urinary incontinence at the end of the day (pressure from a full bladder becomes greater than urinary sphincter pressure). In contrast, a patient with a spastic bladder will have frequent episodes of urinary incontinence throughout the day due to urgency.
Educational objective:
Patients with multiple sclerosis often develop a spastic bladder a few weeks after developing an acute lesion of the spinal cord. These patients present clinically with increased urinary frequency and urge incontinence. Urodynamic studies show the presence of bladder hypertonia.