Dermal Sinus Tracts of the Spine

Scott Elton, M.D., and W. Jerry Oakes, M.D, Departments of Neurosurgery and Pediatric Neurosurgery, Children's Hospital, Birmingham, Alabama

Neurosurg Focus. 2001;10(1) 

In This Article

Discussion

It is commonly believed that children who have a congenital tethered cord benefit from surgical untethering because it prevents neurological deterioration.[3,4,9,14] However, controversy has surrounded the issue of surgery in newly diagnosed adult patients. The incidence of OSD is unknown and, although it is likely that some patients remain asymptomatic and a diagnosis is never made, a subset of patients with the congenital syndrome develop progressive symptoms and signs in adulthood.[2,5,10,12,13] Such deterioration may occur after sudden movements that cause traction on the spinal cord.[10] These may include bending movements, the lithotomy position during childbirth, movement occurring during motor vehicle accidents, and others. Would surgery in adulthood cause similar long-term improvement in function and, if so, at what cost of complications?

In this paper we describe our experience with 34 adult patients who underwent surgical untethering operations. The clinical presentation of these patients is similar to that reported in previous studies,[2,5,6,8,10,11,13,16,17] stressing the predominance of patients presenting with pain -- this being the major difference between adult and pediatric presentations. The surgical complication rate is low. However, it is slightly higher than that in children with the same disease if one were to compare the data with those of pediatric studies.[1,3,4,9] Long-term results are encouraging, indicating the efficacy of surgery in at least some of these patients. In addition, it is obvious that in a substantial number of our patients, the benefits of surgery were not limited to the prevention of deficits; instead we can infer from our data that newly acquired neurological dysfunction in adulthood is often reversible with surgery.

The diagnosis of OSD in an asymptomatic adult patient is still controversial. Adults are thought to have completed their growth curve; therefore, they are less likely to show any neurological deterioration because there has already been rapid spinal column growth in the setting of a spinal cord that is tethered caudally. However, the issue of mechanical stretching of the spine due to trauma or specific postures plays an important role in the development of new symptoms in these patients. In fact, a significant number of our patients, as well as patients reported in other studies, have been shown to have such a history.[10,18] It is impossible to tell how many patients actually remain asymptomatic because, presumably, these persons will rarely seek medical attention. All patients with this condition whom we have evaluated have demonstrated some deterioration in function related to the spinal anomaly. It is difficult to know if asymptomatic patients are not being referred to appropriate centers or if they just do not exist. Often, patients may be unaware of their existing neurological deficits or may underestimate or minimize their significance. A striking example of this is a 48-year-old woman with a lipomyelomeningocele who developed saddle anesthesia and frequent urinary tract infections after being in the lithotomy position during childbirth. (This patient is not included in this study because she was evaluated only recently and has still not undergone surgical untethering.) Her doctor attributed the saddle numbness to an episiotomy incision, even though the numbness extended to the knee joints posteriorly. She did not attribute the urinary tract infections to her lifelong back problem. This same patient also had "hammer toes" all of her life, for which she underwent surgical correction. This case underlines the importance of a detailed neurological history and examination in this group of patients because, initially, this woman described herself as "asymptomatic."

The importance of this article is that it is the only report with long-term surgical outcome data in an adult population with TCS. Although telephone interviews may introduce significant bias, they do supply some information regarding the satisfaction of the patients with their post-operative conditions. In a more objective fashion, we did ascertain how the operation affected the patients' abilities to work and be productive. This information becomes especially important when one considers the number of patients with back pain due to degenerative disease who seek Workers' Compensation benefits and may not show long-term benefit from surgical procedures. We have demonstrated that our patients are distinctly different from these patients; rather, they are similar to the pediatric population with tethered cord in that they are likely to benefit from surgery and become (or continue to be) part of the productive work force.

Finally, the type of surgical untethering needed in adult patients with OSD is beyond the scope of this article.[4,9] Interested readers are referred to representative articles in the literature that offer discussions of these techniques. It is important to state, however, that in our experience, tethered cord operations in adults, in general, have been more difficult to perform than similar procedures in children. In adult patients, intradural structures are frequently scarred and surrounded by significant arachnoidal adhesions that are very likely to contribute to the patients' symptoms; this scarring is often severe enough to make it more difficult to dissect the edge of the spinal cord from the surrounding dura. In addition, the anatomy may be very unusual and confusing. Therefore, caution should be exercised during the dissection, and preoperative computerized tomography and magnetic resonance images must be studied very carefully before surgery.

Since the original publication of these data, the authors have surgically treated, independently, numerous other adult patients with congenital tethering of the spinal cord, and they have achieved similar successes. The use of intraoperative electrophysiological monitoring continues to be controversial, even among the different authors of this paper. In the recent experience of one of the authors (B.J.I.), for instance, intraoperative electromyography has been useful in differentiating between scar tissue and neural structures. It remains true, however, that the most important factor in preventing postoperative neurological deterioration is not any particular technique of surgery and monitoring but the experience of the surgeon in handling these complex congenital anomalies.

Abbreviations used in this paper: OSD = occult spinal dysraphism; TCS = tethered cord syndrome.

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