What are the urologic manifestations of spinal cord disorders?

Updated: Dec 27, 2018
  • Author: Frances M Dyro, MD; Chief Editor: Robert A Egan, MD  more...
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Answer

Answer

Spinal cord lesions produce various types of voiding dysfunction, depending on the level of the neuraxis involved. Acute herniation of a central disk at L5-S1 is a neurosurgical emergency when the patient comes in with sudden onset of painful urinary retention. The nerve roots of the cauda equina that supply the detrusor travel medially. The sensory inputs from the bladder are not affected. In central herniation, patients usually experience no sciatic radiation of pain.

Spinal stenosis in the lumbosacral region, as it begins producing symptoms, usually results in intermittent episodes of urinary retention as a manifestation of intermittent claudication of the conus or cauda equina. Stenosis in the cervical region is more likely to produce long-tract involvement with bladder sphincter dyssynergia; that is, contraction of the bladder is accompanied by abnormal contraction of the sphincteric mechanism.

Spinal cord injury above the sacral segments but below the pontine micturition center results, in the acute phase, in a state of so-called spinal shock. The detrusor is areflexic and insensate. Sphincteric activity continues. The patient may retain a large volume of urine. An indwelling catheter is usually placed to avoid overdistention, which in itself can render the bladder unresponsive.

As spinal shock resolves and reflexes are regained, tapping over the bladder often elicits a bladder contraction. The coordinated voiding regulated by the pontine micturition center is lost because of the disconnection of pathways traveling through the area of spinal cord damage.

Dyssynergic voiding occurs and, if untreated, can result in very low bladder capacity with frequent contractions, poor emptying, high bladder pressures with trabecular formation, and eventually renal failure from hydroureter and hydronephrosis. [34] Before treatment strategies were developed for managing the bladder in spinal cord injury, renal failure was the most common cause of death.

The spinal dysraphisms often lead to voiding dysfunction, [35, 36] the nature of which depends on the spinal level of the abnormality. Meningomyelocele is now diagnosed in utero, and the infant, usually delivered by cesarean section, undergoes neurosurgery in the newborn period. Urodynamic studies and sphincter electromyography (EMG) done shortly after corrective surgery dictate management. With very low lesions, lower-extremity function may be normal while the sphincter is totally denervated. These children should simply wear diapers.

When the dysraphism affects supraspinal segments, the patient may experience inappropriate sphincter contraction with or without bladder contractions. In such patients, intermittent catheterization is instituted in the newborn nursery and continued at home. Repeat studies are done at the ages of 6 months and 1 year. Some children develop innervation of the sphincter and convert from voiding at low pressure to dyssynergic voiding. Management requires intermittent catheterization and usually anticholinergic drugs to reduce bladder contractions.

Late complications are seen during the adolescent growth spurt if tethering of the filum terminale occurs. Late deterioration of bladder function also may be seen in diastematomyelia. In both cases, traction on the conus can compromise voiding function.

Careful examination of the lower back may reveal a hair patch or a sacral dimple as evidence of underlying pathology. One of the author’s patients had no dysfunction until his spinal cord was compromised further by arthritic changes. He was 73 years old and had had no bowel or bladder dysfunction or lower-extremity dysfunction until that time.

Syringomyelia or hydromyelia can occur as a late complication of spinal cord injury or as a congenital lesion. Intramedullary spinal cord tumors, gliomas, or ependymomas are sometimes associated with the development of a syrinx. Because most patients who develop a posttraumatic syrinx have spastic, dyssynergic bladders as a result of their injury, little change is seen.

Syringes of other etiologies, in the author’s experience, seldom cause bowel or bladder dysfunction. Intramedullary cord tumors usually do not cause bladder dysfunction until they become large enough to cause compression of cord substance within the spinal canal.


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