Selective Dorsal Rhizotomy for Spasticity Technique

Updated: Dec 11, 2018
  • Author: Richard CE Anderson, MD; Chief Editor: Kim J Burchiel, MD, FACS  more...
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Technique

Approach Considerations

Although a traditional selective dorsal rhizotomy (SDR) involves a long skin incision with a 5- or 6-level laminectomy or laminoplasty, it can also be performed with a less-invasive approach through a smaller incision and a single level laminectomy. [28] Advantages of this approach include a smaller incision, fewer levels of bone removal or disruption, and less postoperative pain. [11]

Preoperative antibiotics and steroids are given prior to skin incision.

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Selective Dorsal Rhizotomy

The steps of SDR are illustrated in the images below.

After the conus is clearly identified, a single la After the conus is clearly identified, a single laminectomyis done entirely with a Midas Rex craniotome. At least 5 mm of thecaudal conus should be exposed. The laminectomy extends laterallyclose to the facet joint. Courtesy of Tae S Park, MD.
After the dural incision, an operatingmicroscope i After the dural incision, an operatingmicroscope is brought into the field. The L-1 and L-2 spinal roots areidentified at the corresponding intervertebral foramina, and the filumterminale in the midline is found. Courtesy of Tae S Park, MD.
The L-2 dorsal root and the dorsal rootsmedial to The L-2 dorsal root and the dorsal rootsmedial to the L-2 root are retracted medially to separate the L2-S2 dorsalroots from the ventral roots. The thin S3-5 spinal roots exiting fromthe conus are identified. A cotton patty is placed over the ventralroots and lower sacral roots. Courtesy of Tae S Park, MD.
A 5 mm Silastic sheet is placed underthe L2-S2 dor A 5 mm Silastic sheet is placed underthe L2-S2 dorsal roots, after which the sugeon again inspects the L-2 dorsal root at the foraminal exit, the lateral surface of the conusbetween the dorsal and ventral roots, and the lower sacral roots near the filum terminale. The Inspection ensures placement of only the the L2-S2 dorsal roots on top of the Silastic sheet. Courtesy of Tae S Park, MD.
The L-2 dorsal root is easily identified. In an at The L-2 dorsal root is easily identified. In an attempt to identify the L3-S2 dorsal roots, all the dorsal roots are spread over the Silastic sheet and grouped into presumed individual dorsal roots. Then the innervation pattern of each dorsal root is examined with electromyographic (EMG) responses to electrical stimulation with a threshold voltage. Courtesy of Tae S Park, MD.
With a Scheer needle, each dorsal root is subdivid With a Scheer needle, each dorsal root is subdivided into three to five rootlet fascicles, which are subjected to EMG testing. Courtesy of Tae S Park, MD.
Stimulation of an L-2 rootlet fascicle elicits an Stimulation of an L-2 rootlet fascicle elicits an unsustained discharge to a train of titanic stimuli. Courtesy of Tae S Park, MD.
The rootlet is thus spared from sectioning and pla The rootlet is thus spared from sectioning and placed behind the Silastic sheet. Courtesy of Tae S Park, MD.
Stimulation of a rootlet is thus sectioned. Courte Stimulation of a rootlet is thus sectioned. Courtesy of Tae S Park, MD.
The rootlets spared from sectioning are under the The rootlets spared from sectioning are under the Silastic sheet, and the roots to be tested are on top of the Silastic sheet. Note the EMG testing and sectioning of the dorsal roots are performed caudal to the conus. Courtesy of Tae S Park, MD.
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