J Korean Neurosurg Soc.  2020 May;63(3):346-357. 10.3340/jkns.2020.0039.

Retethering : A Neurosurgical Viewpoint

• Lee JY
• Kim KH
• Park K
• Wang KC

• KMID: 2501722
• DOI: http://doi.org/10.3340/jkns.2020.0039

Abstract

During the follow-up period after surgery for spinal dysraphism, a certain portion of patients show neurological deterioration and its secondary phenomena, such as motor, sensory or sphincter changes, foot and spinal deformities, pain, and spasticity. These clinical manifestations are caused by tethering effects on the neural structures at the site of previous operation. The widespread recognition of retethering drew the attention of medical professionals of various specialties because of its incidence, which is not low when surveillance is adequate, and its progressive nature. This article reviews the literature on the incidence and timing of deterioration, predisposing factors for retethering, clinical manifestations, diagnosis, surgical treatment and its complications, clinical outcomes, prognostic factors after retethering surgery and preventive measures of retethering. Current practice and opinions of Seoul National University Children’s Hospital team were added in some parts. The literature shows a wide range of data regarding the incidence, rate and degree of surgical complications and long-term outcomes. The method of prevention is still one of the main topics of this entity. Although alternatives such as spinal column shortening were introduced, re-untethering by conventional surgical methods remains the current main management tool. Re-untethering surgery is a much more difficult task than primary untethering surgery. Updated publications include strong skepticism on re-untethering surgery in a certain group of patients, though it is from a minority of research groups. For all of the abovementioned reasons, new information and ideas on the early diagnosis, treatment and prevention of retethering are critically necessary in this era.

Keyword

Lumbosacral lipoma; Myelomeningocele; Retethering; Incidence; Outcome

Figure

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  Fig. 1. A graph showing SI (cross-sectional area of the syrinx as a percentage of the spinal cord area) of a patient with retethering. The syrinx disappeared completely during the 21-month period after the initial untethering surgery. At postoperative 4.5 years, an increase in SI was noted by sonography, and the patient began to complain of urinary Sx 6 months later (dark arrow). Re-untethering surgery was performed because of the progression of urinary symptoms (light arrow). MRI taken just before the second operation demonstrated further enlargement of the syrinx. Modified from Lee et al. [24] with permission from Oxford Academic. Sx : symptoms, SI : syrinx index, MRI : magnetic resonance imaging.

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  Fig. 2. Operative photographs of skipping the area that shows positive responses on electrical stimulation during the re-untethering surgery. The right side of each photo is the cephalad direction. A and B : Electrical stimulation is performed caudally. At this time, if a positive reaction occurs, stimulation is continued caudally to the site where the response does not occur. A right-angled dissector tip is placed from inside outward at the thinned response-negative area. C : A new perforation is made on this site using microscissors. D : The hole is identified between the subarachnoid space (SAS) and the new perforation site and is enlarged by the right-angled dissector. From this point, crotch dissection is extended downward. E : The preserved roots at the skipped area (black circle) come from the medial side of the lipoma-cord fusion line (red dashed lines) and are embedded in the fibroadipose tissue closer to the SAS, in contrast to the other roots that are exposed to and run through the SAS (black dotted circle). Dura is tagged separately with black silk. Modified from Kim et al. [21] with permission from Elsevier Inc.

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  Fig. 3. Serial changes of bladder shapes following re-untethering surgery. The girl had undergone primary untethering surgery for myelomeningocele just after birth. Despite management with clean intermittent catheterization and anticholinergic medication, her bladder capacity was not changed with increasing age (2015, 3 years old). Morphologically, her bladder was deformed significantly with increased trabeculation (A : See the upper side of the bladder). Following re-untethering surgery on January 2016, the trabeculation became flattened with the normalization of vesical pressure (B). At 4 years after re-untethering surgery, the significant bladder trabeculation seen in the upper wall was nearly normalized (C). PO : postoperative.

Reference

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