Childs Nerv Syst (2004) 20:478–479DOI 10.1007/s00381-004-0921-7 C O M M E N T A R Y

Shokei YamadaDaniel J. WonJaved SiddiqiChenyere ObasiBruce A. Everett

Russell Silver syndrome associatedwith tethered cord syndrome

Published online: 19 May 2004� Springer-Verlag 2004

This commentary refers to the article http://dx.doi.org/10.1007/s00381-004-0919-1

S. Yamada ())Department of Neurosurgery,Loma Linda UniversitySchool of Medicine,11234 Anderson Street, Loma Linda,CA 92354, USAe-mail: yamada1000@worldnet.att.netTel.: +1-909-5584952Fax: +1-909-7842748

D. J. Won · J. SiddiqiDepartment of Neurosurgery,Arrowhead Regional Medical Center,400 N. Pepper Avenue, Colton, CA 93224,USA

C. Obasi · B. A. EverettDepartment of Neurosurgery,Kaiser Permanente Medical Center,9961 Sierra Avenue, Fontana, CA 99855,USA

The article describes an interestingand rare combination of Russell Sil-ver syndrome and tethered cord syn-drome (TCS). The development ofthe insight into whether TCS is a partof this syndrome or not, however, isstill premature until sufficient datahave been accumulated, as the au-thors indicated.

The horizontal sacrum and severescoliosis (60�) may become anotherimportant subject for surgical deci-sion making. Retrospectively, theauthors seem to conclude that thesurgery was justified because of thefindings:

1. The fibrosed, inelastic filum [10]was attached to an elongated cord[1, 3],

2. The cephalic end of the sectionedfilum moved toward the conusafter sectioning the filum, and

3. Postoperatively, the patient’s backmuscles felt looser.

We have surgically treated morethan 100 adults with TCS who failedto show spinal dysraphism (group 2adult TCS patients) [6, 10, 11], as theauthors’ case did. Three of our recent20 patients with a horizontal sacrumand mild to moderate scoliosis pre-sented with severe back and leg pain,and mild neurological motor sensoryand bladder dysfunction. At operationthe filum of each patient was foundby histological studies to be inelasticin a stretch test [6, 10, 11] and glial

tissue of the filum was completelyreplaced by fibrous tissue [11]. Backand leg pain was relieved after sec-tioning the tight filum, and neuro-logical improvement followed.

It is the reviewers’ postulation thatthe exaggerated lumbosacral lordosisand the scoliosis are the manifesta-tions of paravertebral muscle reactionthat reflects the excessive tensionwithin the spinal cord. Changing thespinal column curvature is an ad-justment for the spinal cord to be ableto take the shortest course along theconcave side of the scoliotic andlordotic spinal canal [10]. This natu-ral adjustment minimizes the spinalcord tension. Whether the horizontalsacrum with exaggerated lumbosacrallordosis is linked to TCS or coinci-dental to TCS is still debatable.However, three patients in our serieshad family members report that theirlordosis had been progressive beforesurgery. After untethering proce-dures, all patients showed less scoli-osis and increased flexibility of thelumbosacral spine. Probably, in thesepatients, the congenital nature andacquired progression of the exagger-ated lordosis were not mutually ex-clusive.

Despite such delicate adjustments,why do the scoliosis and lumber lor-dosis progress? At least two mecha-nisms contribute to the increase inspinal cord tension. First, the flexionof the lumbosacral spine elongatesthe spinal canal, resulting in stretch-

479

ing of the spinal cord, which is fas-tened by an inelastic structure [6].Second, the extension of the lumbo-sacral spine can cause a further in-crease in conus and filum tension bysimilar mechanisms to the tighteningof a peg that increases the tension ofa violin string above and below thebridge [10]. Usually the conus orfilum is attached to the posteriorarachnoid membrane at the L5 lami-nal level. The L5 lamina is likely tofunction similarly to the bridge of theviolin, thus for increasing the conusand filum tension on spinal extension[10, 11].

The reviewers emphasize the im-portance of other signs and symptomsin diagnosing adult TCS, as describedpreviously [6, 10, 11]. Among theprotocols established for adult TCS[12, 13], aggravation of back and legpain or initiation of back discomfortis caused by any type of activities toinduce spinal flexion and extension.For example, three typical (3B) pos-tures that straighten the lumbosacralspine are found to accentuate backpain in all patients with adult TCS[10]. They are Buddha-pose sittingwith legs crossed, bending over thesink for tooth brushing or dishwashing and baby holding at thewaist level. Additionally, the patientsare unable to lie supine in bed, andturn laterally in the fetal position.Mild motor dysfunction is detected,especially in small muscles, e.g., theextensor hallucis longus, or in largermuscles, e.g., peroneus longus, pos-terior tibialis, gastrocnemius or ante-rior tibialis, only in the tiptoe-walk-ing test or in the heel-walking test.The maximal walking distance ofpatients usually decreases over a fewmonths to few years.

The following two children aregood examples of TCS patients withscoliosis and minimum neurologicalsymptoms or signs [10]. First of all, a14-year-old girl was referred by a

school health service physician as aneurologically intact patient. How-ever, despite a slender build, she wasunable to touch her fingers beyond10 cm below the knees and to dorsi-flex the ankle joints beyond 90�. Thesphincter tone was diminished.Within 2 weeks of resection of thefibrous filum, she was able to touchher toes and dorsiflex her feet to 60�,and regained normal sphincter con-traction. Secondly, a 14-year-old boywith severe rotational scoliosis (60�)complained of the inability to run forcompetitive soccer for severalmonths. Within 3 months of the un-tethering procedure, he started soccertraining again. In each patient, redoxstudies of cytochrome a, a3 in vivo [4,7, 8] indicated impaired oxidativemetabolism before untethering, andits improvement after resection of theinelastic filum. Histologically, eachfilum was totally replaced by fibroustissue [9].

It is known that there is no elon-gated spinal cord [5, 11] and thickfilum (>2 mm) [2] in a significantnumber of TCS patients. However,the posterior displacement of the co-nus and filum is a consistent MRIfinding in the TCS patient [6, 10, 11].In order to confirm the MRI findingsand enhance the diagnosis of the TCSin each patient, we often performpercutaneous endoscopy, which al-lows for identification of the poste-riorly displaced tight filum or conusbefore surgery [6, 10].

We believe that the authors’ pa-tient definitely benefited from theuntethering procedure, preventingprogression of the scoliosis and re-lieving back muscle discomfort. Ifour protocol of TCS signs andsymptoms in late teen-age and adultpatients is fulfilled, we would bemore confident preoperatively aboutproceeding with untethering proce-dure.

References

1. Fitz CR, Harwood-Nash DC (1975) Thetethered conus. Am J Roentgenol125:515–523

2. Hochhauser L, Caung S, Harwood-NashDS et al (1986) The tethered cord syn-drome revisited. Am J Neuroradiol7:543

3. Hoffman HJ, Hendrick EB, HumphreysRP (1976) The tethered spinal cord: itsprotean manifestations, diagnosis andsurgical correction. Childs Brain 2:145–155

4. Rosenthal MD, Martel JC, LaManna Jet al (1976) In situ studies of oxidativeenergy metabolism during transientcortical ischemia in cats. Exp Neurol50:477–494

5. Warder DE, Oakes WJ (1993) Tetheredcord syndrome and the conus in a nor-mal position. Neurosurgery 33:374–378

6. Yamada S, Lonser RR (2000) Adulttethered cord syndrome. J Spinal Disord13:319–323

7. Yamada S, Zinke DE, Sanders DC(1981) Pathophysiology of “tetheredcord syndrome.” J Neurosurg 54:494–503

8. Yamada S, Iacono RP, Andrade T et al(1995) Pathophysiology of tetheredcord syndrome. Neurosurg Clin N Am6:311–323

9. Yamada S, Iacono RP, Douglas CD etal (1996) Tethered cord syndrome inadults. In: Yamada S (ed) Tethered cordsyndrome. American Association ofNeurological Surgeons, Park Ridge, IL,pp 139–165

10. Yamada S, Iacono R, Yamada BS(1996) Pathophysiology of tetheredcord syndrome (chapter 4). In: YamadaS (ed) Tethered cord syndrome. Amer-ican Association of Neurological Sur-geons, Park Ridge, IL, pp 29–48

11. Yamada S, Won DJ, Kido D (2001)Adult tethered cord syndrome: newclassification correlated with symp-tomatology, imaging and pathophysiol-ogy. Neurosurg Q 11:260–275

12. Yamada S, Siddiqi J, Won D et al(2003) Symptomatic protocols for adulttethered cord syndrome [abstract]. Pre-sented at the Western NeurosurgicalSociety, September 20–24, Kohala,Hawaii

13. Yamada S, Siddiqi J, Won D et al(2004) Symptomatic protocols for adulttethered cord syndrome [poster]. Pre-sented at the American Association ofNeurological Surgeons, May 1–4,Orlando, FL