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Background
Preserving renal integrity and achieving continence are the primary urologic objectives for lipomyelomeningocele (LMM) and myelomeningocele (MM). We have therefore viewed LMM and MM the same: at risk for issues in the short and long term. Unlike MM, many LMM present with a cutaneous lesion and no evident neurological, orthopedic or urological dysfunction. Indications for and timing of tethered cord release (TCR) in LMM are therefore controversial. In order to minimize risk of deterioration, our practice has been early TCR with longitudinal follow-up to monitor function. Expectations for urinary dysfunction, continence and potential for intermittent catheterization (CIC) following TCR in LMM have not been well established and are important for parental expectations and for provision of safe but appropriate care. We hypothesize that anatomic and functional factors, as well as early and complete TCR, determine urologic outcomes. We examine predictors for long-term continence/CIC after primary TCR.
Methods
We identified 143 patients who underwent TCR for LMM by two neurosurgeons in our multidisciplinary spina bifida clinic between 1995 and 2010. Patients with concomitant anorectal/genitourinary anomalies, filar lipoma, fatty filum, previous TCR, and follow up <1 year were excluded. Analysis was limited to patients who were either toilet trained or older than 6 years at last follow up. LMM was classified as dorsal, distal, transitional, or chaotic. Pre- and post-TCR urologic status was assessed. Ability to achieve urinary continence, with or without CIC, was the primary outcome.
Results
A total of 56 patients (27 males and 29 females) with LMM met strict inclusion criteria. Median age at surgery was 4.4 months (range 1.0-224 months) with an average follow-up of 10 years (range 1.3-19.1 years). 68% (38/56) of these patients were asymptomatic at presentation (cutaneous lesion only or incidental finding on screening). Clinical presentation included urologic symptoms in 9% (5/56), with a median age at surgery of 108 months in this subgroup. At last follow-up, 86% of patients (48/56) were continent either spontaneously (38) or were dry on CIC (10). Eight were incontinent at last follow-up, with 3/8 on CIC. Of the 5 who presented with urologic symptoms, all are continent but 4/5 (80%) require CIC. Overall 23% of patients require CIC. Continence at last follow-up was not significantly associated with any anatomic, surgical or functional variable (Table 1).
Conclusions
Among patients with primary TCR for LMM, 91% of whom were asymptomatic urologically at presentation, prospects for continence were excellent. It is not clear if this result is related to early TCR or close urologic follow-up. In this group, there was no significant difference in long-term continence status based on any of the studied parameters. Families can anticipate 23% likelihood of CIC over the long term, considerably less than in MM, but long term urologic follow-up is still strongly recommended.
Table 1. Predictors of Urinary Continence

	Post-op continence* status		p- value
	Continent	Incontinent
Total (n=56)	48 (86%)	8 (14%)
Sex Male Female	23 (85%) 25 (86%)	4 (15%) 4 (14%)	1.0
Median age at TCR (months)	4.9	3.9	0.992
Presenting Symptoms Asymptomatic (cutaneous lesion only, incidental) Symptomatic (urologic, ortho)	33 (87%) 15 (83%)	5 (13%) 3 (17%)	0.703
Surgery Complete Partial	36 (86%) 12 (86%)	6 (14%) 2 (14%)	1.0
Lipoma type Dorsal Distal Transitional Chaotic	21 (84%) 14 (93%) 12 (80%) 1 (100%)	4 (16%) 1 (7%) 3 (20%) 0	0.747
Conus Position Low lumbar (L4, L5) Lumbosacral Sacral	18 (86%) 3 (75%) 27 (87%)	3 (14%) 1 (25%) 4 (13%)	0.708

*Continence is defined as dry with or without CIC