Is the size of the lesion a reliable predictor of functional deficit or ultimate outcome?

• A. Yes
• B. Somewhat
• C. No
• D. Not entirely

Answer: (D)

The main idea here is that outcome in spina bifida is governed more by what parts of the nervous system are involved and how that involvement affects function, rather than by how big the lesion appears. The neurological level of involvement—motor and sensory deficits at specific segments, involvement of the conus medullaris, and the integrity of the spinal cord—drives functional ability far more than the external size of the defect. Two individuals can have lesions that look similar in size but differ greatly in function because one has more intact neural tissue or fewer associated problems that worsen outcomes. Conversely, a larger lesion might not translate to proportionally worse function if the critical tracts are spared or if the deficit is concentrated in non-functional areas. Other factors matter just as much or more: the presence and management of hydrocephalus and Chiari II malformation, tethered cord, syringomyelia, orthopedic issues, and how well rehabilitation, mobility training, and urinary/renal care are implemented. Because these variables collectively shape what a person can do and how they develop, lesion size is not a wholly reliable predictor of functional deficit or ultimate outcome.