Neurologic and Urodynamic Correlation  

Discrepancy between the Neurologic and Urodynamic Findings

  • SCI patients were classified to have level of injury on the basis of somatic neurologic finding (dermatome and reflex, and etc) and anatomical finding (imaging study incl. spinal MRI).
  • In general, there is a correlation between the neurologic level of injury and the expected vesicourethral function (urodynamic findings). But this is neither absolute nor specific.
  • The discrepancy is prominent especially in the group of SCI patients with lesions at T10 to L2. (The spinal cord itself ends between the L-1 and L-2 vertebrae)
  • Flaccid lower extremities are not always matched with an areflexic bladder. Likewise, spastic type upper motor lesions are not always associated with an overactive bladder. This is why urodynamic study should be done

Discrepancy between the Subjective Voiding Symptoms and Urodynamic Findings

  • Voiding symptoms predict the type of vesicourethral dysfunction to some degree in SCI patients
  • However in general, it is not accurate to predict specific dysfunction based on voiding symptoms without a urodynamic study. Patients with SCI can have dangerous bladder pressures with relatively few symptoms and in males with no incontinence
  • Symptoms correlate with urodynamic finding very poorly in patients with neurogenic bladder due to Mutiple Sclerosis [Bemelmans 1991].
  • ‘No incontinence’ does not mean ‘no problem in the lower urinary tract’.

Level of Injury and the Urodynamic Findings: High Correlation?

  • Blaivas correlated clinical and urodynamic data from 550 patients with either congenital or acquired SCI or disease. A significant portion of the patients with cervical lesions exhibited detrusor areflexia. On the other hand, the patients with sacral lesions also ahowed either detrusor hyperreflexia or detrusor striated sphincter dyssynergia.

Causes of Discrepancy

  • Degree of completeness of the injury:
    • All typical “classic” patterns according to level of injury described in the textbook is based on the assumption that the injury is complete transaction.
    • Complete anatomic transection is rare in the actual situation.
  • Multiple level injuries:
    • There is a possibility of the existence of multiple level of injury, even though what is seen somatically may reflect a single level of injury.
    • Even occult brain damage may coexist

Lessons from the Facts

  • A ‘Lower motor neuron lesion’ does not mean the bladder is safe:
    • In lower motor neuron lesion an areflexic bladder can exist with a significant outlet resistance. This condition may ultimately lead hydronephrosis or VUR. (link to ->Tx-6-1) Problems Encountered During Long-term Follow-up /1. Micturition and Urinary Incontinence)
  • In cases with a specific level of injury
    • Somatic findings do not always completely explain urodynamic findings.
    • The level of injury is not always associated with a certain category of lower urinary tract dysfunction
  • Incontinence and risk
    • Physicians commonly assume that the lower urinary tract is fine if there is no incontinence- this is incorrect.
    • The severity of incontinence does not correlate the severity of the neurogenic bladder dysfunction.
  • Decision making should be always based on the individual urodynamic findings.
    • Neurological examination is not an alternative to an urodynamic study.
    • Inferences from the neurologic history and evaluation may not correlate with urodynamic findings in SCI individuals.
Key Points of This Section
  • The determined level of injury has an inconstant relationship to the type of bladder and urethral dysfunction in patients with SCI.
  • Multiple sclerosis patients symptoms of bladder dysfunction are not related to urodynamic abnormalities nor do they suggest an establish type of bladder dysfunction has changed.
  • Nothing short of a urodynamic study can precisely describe lower urinary tract dysfunction and allow the assessment of the risk posed by a given bladder dysfunctional state.

References

  • Bemelmans BL, Hommes OR, Van Kerrebroeck PE, Lemmens WA, Doesburg WH, Debruyne FM. Evidence for early lower urinary tract dysfunction in clinically silent multiple sclerosis. J Urol. 1991 Jun;145(6):1219-24.
  • Blaivas JG: The neurophysiology of micturition: A clinical study of 550 patients. J Urol 1982;127:958–964.
  • Kaplan SA, Chancellor MB, Blaivas JG: Bladder and sphincter behavior in patients with spinal cord lesions. J Urol 1991;146:113–117

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