adult spina bifida

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J Neurosurg Spine 15:258270, 2011

258 J Neurosurg: Spine / Volume 15 / September 2011

SPINALdysraphic lesions are rare pathological enti-ties. With folate acid substitution during pregnancyand prenatal diagnosis of dysraphic malformations

often leading to termination of pregnancy, the number ofchildren with spina bida aperta has been reduced dra-

matically in Western countries. In contrast, patients withoccult spinal dysraphism are often overlooked, eventhough their disease is often far from occult given the cu-taneous manifestations in many of them. With early diag-nosis of these lesions, however, there remains an ongoingdebate of whether asymptomatic patients with a tetheredcord should undergo prophylactic surgery.

Since 1991, data obtained in all patients with spinalcord pathological entities such as tumors, syringomyelia,

or dysraphism have been entered into a spinal cord data-base at the authors institution and the patients have beenmonitored clinically in prospective fashion. In 1994, a ret-rospective study described spinal dysraphism in 23 adultpatients who had been treated since 1977. The authors

concluded that surgery should be reserved for symptom-atic patients.39The present study presents the results ac-quired in adult patients with tethered cord syndrome thatwas not diagnosed in childhood; the patients presentedbetween 1991 and 2009 and were managed according tothis policy. Do all adult patients with tethered cord syn-dromes eventually become symptomatic with progressiveneurological decits? Does untethering surgery providea long-term benet in adults? It was the purpose of thisstudy to determine the short- and long-term results of sur-gery in these patients and to compare their outcome withthose obtained in patients who underwent conservativetreatment.

Tethered cord syndrome in adults

Clinical article

JRGKLEKAMP, M.D.

Department of Neurosurgery, Christliches Krankenhaus, Quakenbrck, Germany

Object.The treatment of tethered cord syndromes in adults is discussed regarding the natural history and surgi-cal indications. The author analyzes data obtained in patients who were diagnosed with a tethered cord in adulthoodand either underwent surgical or conservative therapy between 1991 and 2009.

Methods.Since 1991, data obtained in 2515 patients with spinal cord pathologies were entered into the spinalcord database, and prospective follow-up was performed through outpatient visits and questionnaires. Of the 2515patients, 85 adults with a tethered cord syndrome formed the basis of this study. The tethering effect was caused eitherby a split cord malformation, a thick lum terminale, a conus medullaris lipoma with extradural extension, or variouscombinations of these mechanisms. The mean age of the patients was 46 13 years (range 2374 years) and the meanfollow-up duration was 61 62 months. Two groups were distinguished based on the absence (Group A, 43 patients)or presence (Group B, 42 patients) of an associated lipoma or dysraphic cyst (that is, dermoid, epidermoid, or neuren-teric cyst). Surgery was recommended for patients with symptoms only. Short-term results were determined within 3months of surgery, whereas long-term outcomes (clinical recurrences) were evaluated using Kaplan-Meier statistics.

Results.For all patients, pain was the most common major complaint. Severe neurological decits were rare.In Group A, 20 of 43 patients underwent surgery, whereas in Group B 23 of 42 patients underwent surgery. Amongindividuals who did not undergo surgery, 17 patients refused surgery and 25 patients underwent recommended con-servative treatment. Short-term postoperative results indicated a signicant improvement of pain and a stabilizationof neurological symptoms. Long-term results showed a good prognosis in patients in whom rst-time (that is, non-revision) surgery achieved successful untethering, with a 10-year rate of neurological stabilization in 89% of GroupA and a 10-year rate of neurological stabilization in 81% of Group B patients. The benet of secondary operationsin Group B was limited, with eventual clinical deterioration occurring in all patients within 10 years. For patientstreated conservatively, follow-up information could be obtained in 33 of 42 patients. Twenty-eight patients remainedin stable clinical condition. Only 5 of the conservatively treated patients experienced clinical deterioration over time;in 4 of these individuals with deterioration, surgery had been recommended but was refused by the patient. The clini-cal recurrence rate in all conservatively treated patients was 21% after 10 years. With a recommendation for surgerythis gure rose to 47% within 5 years.

Conclusions.Surgery in adult patients with a tethered cord syndrome should be reserved for those with symp-toms. In surgically treated patients, pain relief can often be achieved, and long-term neurological stabilization tendsto persist more often than it does in conservatively treated patients. A conservative approach is warranted, however,in adult patients without neurological decits. Revision surgery in patients with complex dysraphic lesions should beperformed in exceptional cases only. (DOI: 10.3171/2011.4.SPINE10504)

KEYWORDS tethered cord syringomyelia neurenteric cyst split cord malformation dermoid cyst spinal lipoma

Abbreviation used in this paper:KPS = Karnofsky PerformanceScale.


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Adult tethered cord syndrome

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Methods

A total of 2515 patients presented to the NordstadtHospital in Hannover, Germany, between 1991 and 2003,or the Christliche Krankenhaus in Quakenbrck, Ger-many, between 2004 and 2009, with spinal cord patholo-

gies and relevant data were entered into the spinal corddatabase. Apart from general patient data and specicfeatures of each spinal cord pathological entity, the neu-rological examinations before surgery, before dischargefrom the hospital, after 3 months postoperatively, andyearly thereafter were analyzed for individual symptomsaccording to a scoring system for individual symptoms(Table 1).40Patients were also evaluated according to theKPS.36 For each patient, the most important symptomwas noted as the main symptom. Among these 2515 pa-tients, 126 adult patients presented with spinal dysraphiclesions. Of these, I excluded 13 patients with surgicallytreated myelomeningoceles and Chiari Type II malforma-tions who presented with signs of a retethered cord and28 patients with spinal hamartomas (lipoma or dysraphiccyst) without a tethered cord. Eighty-ve patients with atethered cord not diagnosed in childhood were entered inthis study. All patients presented with MR images. De-pending on the pathology, CT scanning and conventionalradiography were also performed. Myelography and post-myelograhic CT scanning were performed only in excep-tional cases, such as complex pathologies or after previ-ous surgeries. Two categories of patients were dened:Group A: patients with either a low-positioned conusmedullaris below L-2, a thick lum terminale, or a splitcord malformation (that is, a tethered cord syndrome only[43 patients]) and Group B: patients with a combination ofa tethered cord and a hamartoma (42 patients).

In general, surgery was recommended as soon as

neurological symptoms were present. In patients withcomplex dysraphic lesions in Group B, surgery was re-served for those with progressive neurological symptoms.

Surgical strategies depended on the individual patho-logical entity. In patients with a tethered cord due to athick lum terminale, the lum was transected. In pa-tients with a split cord malformation, we resected thetethering components at the level of the split cord andtransected the lum in cases with a low-lying conus.26,57,58

The extent of untethering was evaluated intraoperativelyand considered successful if all tethering componentscould be released. For all dysraphic cysts, a complete re-section, including the capsule, was intended. Wheneverpossible a lipoma was left untouched to avoid arachnoidadhesions. A lipoma mass was reduced only if the spinal

cord and lipoma would not t comfortably in the spinalcanal and dural sac or if the lipoma had extradural exten-sion. In such cases, intra- and extradural components ofthe lipoma were separated from each other at the level ofthe dura, the extradural part in the subcutaneous spacewas left in place to avoid problems of wound healing, andthe intradural part was reduced to accommodate the cordand the rest of the lipoma in the reconstructed dural sac.Whenever I partially resected a lipoma, I attempted clo-sure of the capsule to avoid recurrent tethering. No ad-ditional measures such as shunt placement were taken inpatients with an associated syrinx. In all Group B patientsand in Group A patients with a split cord, duraplasty wasperformed to avoid retethering. Except for 3 patients

treated early in the series with fascia lata grafts, articialmaterials were used. The duraplasty graft was lifted offthe spinal cord by means of tenting sutures to minimizethe risk of retethering.41,42

After discharge from the hospital, all surgicallytreated patients were examined after 3 months, and yearlyfollow-up information was obtained by further outpatientvisits or questionnaires. Likewise, conservatively treatedpatients were asked to complete follow-up questionnaires.

For statistical tests of signicance, Student t-tests andFisher exact tests were employed. Long-term follow-updata were analyzed with Kaplan-Meier statistics34to de-termine the percentages of patients with either a stableneurological status or progressive symptoms (that is, aclinical recurrence). For all statistical analyses, the soft-

ware package PC-Stastik version 4.0 (Hoffmann-Soft-ware) was employed. Surgical morbidity was dened as anew, permanent postoperative decit or a permanent ag-gravation of a preexisting decit.

Results

Preoperative Data

Since 1991, 85 adult patients presented with either a

TABLE 1: Neurological scoring system

Score

Neurological Decit

Pain

Sensory Disturbance,

Dysesthesias Motor Weakness Gait Ataxia Sphincter Function5 none normal full power normal normal

4 slight, no medication present, not signicant movement against

resistance

unsteady, no aid slight disturbance,

no catheter

3 good control w/ medication signicant, function not re-

stricted

movement against

gravity

mobile w/ aid residual, no cath-

eter

2 insufcient control w/ med-

ication

some restriction of function movement w/o

gravity

few steps w/ aid rarely incontinent

1 severe despite medication severe restriction of func-

tion

contraction w/o

movement

standing w/ aid frequent catheter

0 incapacitating incapacitated function paralysis paralysis permanent catheter


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tethered cord syndrome (Group A, 43 patients) or a com-bination of a tethered cord with a hamartoma (Group B,42 patients). The mean age at clinical presentation forthe entire group was 46 13 years (range 2374 years),with a mean clinical history of just over 8 years (99 141 months) before diagnosis and no signicant differ-

ences between both groups (91 144 months in GroupA and 106 139 months in Group B). Group A patientswere signicantly older than Group B patients (51 15years vs 44 12 years, respectively; p = 0.0082 [t-test]).Overall, female patients predominated in this study. Thisdominance was more pronounced in Group A than inGroup B (female/male ratio 35:8 and 26:16, respectively;p = 0.0288 [Fisher exact test]).

Table 2 lists the cutaneous manifestations and radio-logical features for both groups. Cutaneous stigmata weremore common in Group B (p = 0.02 [Fisher exact test]).Dermal sinuses, however, were observed in both groupsin similar proportions. No such patient gave a history ofmeningitis. Syringomyelia and split cord malformations

were signicantly more common in Group A (p


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nicant arachnoid adhesions, which were either due to aprevious operation or meningeal reactions related to rup-tured dermoid cysts.

Outcome

Surgery-related complications were encountered in8 cases (16% [8 of 51 operations]). We observed no dif-ferences between the patient groups. There were 3 CSFleaks, 2 postoperative hematomas, 2 urinary tract infec-tions, and 1 impetigo contagiosa. Permanent surgical

morbidity was observed only in Group B at a rate of 7%and this was restricted to revision surgeries. The meanfollow-up period for all patients in the study was 60 63months; for those who underwent surgery it was 60 65months, and for those who did not undergo surgery it was60 58 months.

Looking at short-term results after 3 months, 31(61%) of 51 operations resulted in clinical improvement,whereas 17 operations (33%) left the patients unchangedin that period. Three operations in Group B patients werefollowed by early clinical deterioration. The clinicalscores for individual symptoms within the rst 3 months

FIG. 1. Left:Sagittal T1-weighted MR image demonstrating a largedermoid cyst from L-4 to L-5. Right: Corresponding axial imageshowing a split cord malformation Type 1 and attachment of the cyst tothe left hemicord. This 50-year-old patient presented with an almost 30-year history of back pain and a slight distal paraparesis but no sphinc-ter problems. Surgery was not recommended and would have been

refused by the patient. She has been in stable condition for 11 years.

FIG. 2. A and B:Sagittal T2-weighted MR images revealing a largecystic C6T1 lesion associated with a spina bida occulta at thesesegments, a C7T1 Klippel-Feil deformity, and a large syrinx from C-2to C-6. The 50-year-old patient presented with a 4-month history of arapidly progressing tetraparesis rendering him unable to walk by thetime of presentation. Intraoperatively, a dermal sinus was discoveredunderneath the skin, which led to a large neurenteric cyst as part ofa split cord malformation Type 2 with both hemicords on either side.The dermal sinus and the neurenteric cyst were removed completelyto untether the cord. C and D:Postoperative sagittal and axial T2-weighted images demonstrating the complete resection of the cyst, areduction of the syrinx, and the 2 hemicords in the reconstructed duralsac. The patient improved signicantly and regained his ability to walkbut required a walker.

FIG. 3. Sagittal T1-weighted image demonstrating a L24 conus lipo-ma with a tethered cord in a 54-year-old woman with a 35-year historyof back pain, as well as moderate myelopathy with a distal paraparesisand minor sphincter problems. She refused surgery and her conditionhas remained unchanged for 9 years.


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are presented in Table 6. For both groups, signicant painrelief was achieved (p


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operations (recurrence rates of 11% after 10 years inGroup A and 31% after 10 years in Group B) (Fig. 6B)compared with secondary surgeries (Fig. 6C). Whetheruntethering was fully achieved in Group B affected long-term results after rst operations only (clinical recurrencerates of 19% after 10 years vs 60% after 5 years withincomplete tethering, respectively) (Fig. 6D), whereas allpatients undergoing a secondary operation in Group Beventually experienced new neurological problems with-in 10 years irrespective of the degree of untethering (Fig.6C) (Table 7).

Long-term results of in nonsurgically treated patientswere analyzed to determine how many patients had ex-perienced a clinical worsening during follow-up. Of 23conservatively treated patients in Group A, 7 were lostto follow-up, whereas of 19 nonsurgically treated patientsin Group B 2 were lost to follow-up. In the remaining 33patients (Figs. 1 and 3), no neurological deterioration was

observed among those in whom surgery had not been ad-vised, except in 1 such patient in whom surgery at anoth -er hospital resulted in permanent morbidity. Progressiveneurological decits were detected exclusively in symp-tomatic patients who had refused surgery despite receiv-ing recommendation to undergo the procedure. Four suchpatients experienced neurological deterioration within2, 8, 20, and 24 months of their initial presentation. Ac-cording to Kaplan-Meier analysis, the rate of clinical re-currences among all nonsurgically treated patients was21% after 10 years. For those patients who had refused anoperation, the corresponding value rose to 47% within 5years (Table 7) (Fig. 6C). Compared with all patients un-dergoing a rst successful untethering procedure, with aclinical recurrence rate of 16% after 10 years, this differ-ence almost reached statistical signicance (p = 0.0519,log-rank test).

Discussion

Diagnosis and treatment of congenital malformations

such as the tethered cord syndrome in adults is a chal-lenging task, because these malformations are rare andpresent a wide spectrum of pathologies: some are verysimple and easy to manage, such as a low-lying conuswith a thick lum terminale, whereas others are verycomplex with combinations of a split cord malformationand a dysraphic cyst or a lipoma and vertebral dysplasias.In such instances, surgery can be associated with con-siderable morbidity. Unlike pediatric patients, adults maypresent with additional degenerative problems that maycomplicate treatment even further.

Diagnosis and Clinical Presentation

Even though the term occult spinal dysraphism isused for the pathological entities described in this paper,the disease is anything but occult in many patients. Footdeformities, abnormal hair growth, capillary hemangio-mas, or a dermal sinus can be found on inspection in alarge number of these patients,21 and they were foundmore commonly in the more complex Group B patientsin the present study (Table 2).

Magnetic resonance imaging is most often used tomake the neuroradiological diagnosis. The radiologicaldiagnosis of a tethered cord is based on a low positionof the conus below L-2,7,38demonstration of a thickenedlum terminale, the presence of a split cord malforma-tion, or a lipoma with extradural extension. Furthermore,

TABLE 3: Clinical signs and symptoms at presentation*

Group Hypesthesia Dysesthesia Pain

Motor

Weakness

Gait

Ataxia

Sphincter

Disturbance KPS Score

A: tethered cord

surgery no surgery

61

6855

34

4130

82

7785

48

5940

50

4555

50

5940

79 9

78

779 10

B: tethered cord & hamartoma

surgery

no surgery

70

68

75

27

25

31

80

79

81

65

75

56

63

68

56

65

75

56

74 12

72 11

77 13

* Except for KPS scores, which are presented as the meanSD, each value is a percentage.

TABLE 4: Clinical scores at presentation for surgically and

nonsurgically treated patients*

Decit

Group

A: Tethered

Cord

B: Tethered Cord &

Hamartoma

hypesthesia

surgery

no surgery

3.8 0.8

4.1 1.0

3.6 1.2

4.0 0.9

dysesthesia

surgery

no surgery

4.1 1.0

4.6 0.8

4.5 1.0

4.5 0.8

pain

surgery

no surgery

3.4 1.0

3.5 0.9

3.3 1.1

3.2 0.9

motor weakness surgery

no surgery

4.3 0.7

4.5 0.8

3.6 1.2

4.3 0.9

gait ataxia

surgery

no surgery

4.3 0.8

4.2 0.9

3.9 1.2

4.3 1.0

bladder dysfunction

surgery

no surgery

4.0 1.1

4.2 1.2

3.6 1.4

4.3 0.8

* Scores are based on the classication presented in Table 1 and are

presented here as the mean SD.


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TABLE 5: Operations in patients with a tethered cord

No. of Patients

Group No. of Patients Untethered

Untethering

Incomplete

Complete

Resection Partial Resection Decompression

A: tethered cord lum

split cord

1st surgery

revision surgery

17

5

11

9

15

5

2

2

B: tethered cord & hamartoma

lipoma

dermoid cyst

lipoma & dermoid

neurenteric cyst

epidermoid cyst

1st surgery

cysts

revision surgery

cysts

20

7

9

5

14

2

3

2

1

15

7

3

2

1

1

5

2

2

2

2

1

6

1

9

2

2

1

1

4

8

TABLE 6: Early postoperative clinical results

Group

Mean Neurological Score

Group A:

Tethered Cord

Group B: Tethered

Cord & Hamartoma

Groups A & B:

1st Op

Groups A & B:

Revision Surgery

Groups A & B:

Split Cord

hypesthesia

preop

postop

3 mos

3.8 0.8

3.8 0.8

3.8 0.8

3.6 1.2

3.6 1.3

3.8 1.2

4.0 0.8

4.0 0.8

4.2 0.7

2.9 1.2

2.8 1.4

2.8 1.3

3.4 1.2

3.2 1.3

3.3 1.2

dysesthesia

preop postop

3 mos

4.1 1.04.3 0.8

4.4 0.8

4.5 1.04.6 0.8

4.5 0.9

4.4 0.94.6 0.7

4.6 0.7

4.4 1.24.3 1.0

4.1 1.2

3.7 1.14.0 0.9

3.9 1.0

pain

preop

postop

3 mos

3.4 1.0

3.9 0.7

3.9 0.7*

3.3 1.1

3.8 1.0

4.2 0.9*

3.3 1.0

3.9 0.8

4.2 0.7*

3.4 1.2

3.6 1.1

3.8 1.1

3.2 1.0

3.6 0.9

3.8 0.9

motor weakness

preop

postop

3 mos

4.3 0.7

4.4 0.6

4.4 0.6

3.6 1.2

3.6 1.1

3.9 1.1

4.0 1.1

4.1 1.0

4.2 0.9

3.4 0.9

3.4 0.9

3.8 1.1

3.6 1.2

3.7 1.1

3.8 1.1

gait ataxia

preop

postop

3 mos

4.3 0.8

4.4 0.7

4.4 0.7

3.9 1.2

3.9 1.3

4.0 1.1

4.2 1.2

4.3 1.1

4.3 1.0

3.7 0.8

3.6 1.1

3.8 1.0

3.6 1.4

3.7 1.4

3.8 1.3

bladder dysfunction

preop

postop

3 mos

4.0 1.1

4.0 1.0

4.2 1.0

3.6 1.4

3.2 1.6

3.5 1.5

3.9 1.3

3.7 1.4

4.0 1.4

3.3 1.2

3.0 1.5

3.3 1.1

3.8 1.1

3.5 1.4

3.8 1.0

KPS score

preop

postop

3 mos

77 7

78 6

79 8

72 11

72 14

72 19

75 11

76 12

76 17

72 4

69 12

71 9

71 12

68 14

72 14

* Signicant differences between pre- and postoperative scores af ter 3 months (p < 0.01, Fisher exact test). Values are shown

as mean SD.


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shortened nerve roots and arachnoid adhesions betweenspinal cord and dura after previous operations or rupturesof dermoid cysts may contribute to the tethering problem.Remnants of cyst contents indicating arachnoid reactionsmay be found attached to spinal cord, cauda equina, 50,52,53or inside the central canal.23,25,35,37Various combinationsof these tethering mechanisms may be found in an indi-vidual patient.

For all pathological entities associated with changesof the bony anatomy, bone window CT scans are recom-mended.57In such instances, bony landmarks are the best

guides during surgery. In complex dysraphic malforma-tions, a 3D reconstruction of CT images can be helpful.However, such examinations do expose the patient to highdoses of radiation and should not be performed routinely.

Overall, patients presented at a mean age of 46 13years (range 2374 years). Similar clinical and dysraphicfeatures were reported in other adult series30,31,49,65as wellas those of mixed adult and pediatric populations.69Thefemale predominance among adult patients with a tetheredcord syndrome is a well-established observation.5,31,47,65Acomparison between adult and pediatric series, however,discloses a higher proportion of neurological decits with

sphincter problems, in particular in children, in whompain is a much more signicant problem.21

In the present study, adults had a long clinical histo-ry before presentation. Symptoms were present on aver-age for about 89 years. The pathophysiology of teth-ered cord syndrome is related most of all to chronicischemia.74,75 Symptoms may be initiated by sudden ef-forts, exaggerated bending of the back, trauma, obesity,or pregnancy.5,30,63 In this study, the initial symptom inthe long clinical history was often pain, which precededthe development of neurological decits for quite some

time.5,17,30,49 In most patients, neurological decits wereminor at the time of presentation despite the long delaybefore diagnosis. Sphincter disturbances affected half totwo-thirds of the patients (Table 3). Most patients indi-cated they had only minor dysfunctions such as a feelingof residual urine after voiding or not being able to holdwater for as long as they had been used to. Self-cathe-terization or incontinence was present in 8% of these pa-tients only.50As one would expect, neurological decitswere more likely and were severe in patients with morecomplex malformations (Tables 3 and 4).

In this series, none of the patients with a dermal si-

FIG. 6 . Long-term results (A) for all patients of Groups A and B (p = 0.1119, log-rank test), (B) for first-time operations inpatients of Groups A and B (p = 0.179, log-rank test), for (C) all patients combined comparing first-time operations, revision sur-geries, and patients who refused surgery (p = 0.0036, log-rank test), and (D) for first-time operations in patients with successful

untethering in Groups A and B and in patients with partial untethering in Group B (p = 0.0025, log-rank test). Gr. = group; Part.Un. = partial untethering; Rec. = recommended; Rev. = revision; Unteth. = complete untethering.


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nus had a history of meningitis. This may be related to aselection bias as infections are not uncommon in childrenwith dermal sinus tracts.64Finally, no patient with an as-sociated syrinx demonstrated ascending neurologicaldecits correlating to an expanding syrinx. Therefore, sy-ringomyelia was considered clinically irrelevant in thesepatients.

Surgical Management: Hamartomas and Syringomyelia

Dysraphic cysts require a complete resection includ-ing their capsule to avoid a recurrence.41 Excellent out-

comes have been reported after complete resections ofneurenteric cysts1,4,6,12 despite recurrence rates reportedas high as 37%13 and 38%.66 In the present series, 7 of12 cystic hamartomas were removed completely. In rstoperations, 6 of 7 cysts could be totally resected, whereasonly 1 of 5 was completely removed in a second opera-tion. Recurrent dermoid cysts or arachnoid reactions aftercyst rupture may cause severe problems to identify anddissect the cyst capsule without damage to spinal cord ornerve roots.5052It has been estimated that no more than40% of dermoid cysts are totally resectable.10 A com-plete resection was achieved in 4 of 8 patients with der-moid cysts in this study. Mathew and Todd52removed 6of 21 dermoid cysts in the cauda equina area completely,whereas Lunardi et al.50achieved a complete resection of

3 of 8 dermoid cysts.Because lipomas do not have any proliferating poten-

tial18and behave according to the rest of the body fat,19,63neurological progression may be related to weight gain,pregnancy, or steroid therapy, with possible restitution af-ter weight loss, child birth, or termination of steroids. Theabsence of proliferative potential raises the question ofwhether a lipoma should be resected at all. Some studieshave emphasized the importance of a complete lipomaresection to achieve a favorable long-term outcome,21,61whereas others found no such correlation.63After partiallipoma resections, severe arachnoid scarring may attach

the conus and lipoma to the dura.61,63This is probably themain reason for the rather unsatisfactory outcome of sur-gical revisions in Group B patients. Therefore, Pang etal.60,61changed their strategy for lipoma surgery to a moreaggressive approach; they completely resected the lesionand closed the placode with pial sutures to lower the risk

of postoperative retethering.In the present series, a complete lipoma resection was

never attempted. If the lipoma was small and the spinalcord or cauda appeared not to be compressed, tether-ing was considered the exclusive cause of neurologicalsymptoms. In such cases, the lipoma was left intact andthe cord was untethered (Fig. 3). This policy avoids anyformation of arachnoid adhesions associated with partialresections. If the lipoma appeared to be of considerablesize sufcient to compress spinal cord and cauda or wasinvolved in the tethering, its mass was reduced and theouter capsule was preserved and sutured at the end of thedebulking. This was considered to limit the risk of post-operative tethering, analogous to the effect of pial sutures

after removal of intramedullary tumors.41

In this series every syrinx was considered asymp-tomatic70and of small size in most patients. Shunting of asyrinx associated with a tethered cord has been advocatedby some authors.2,20,21,32However, the course of a syrinx isrelated to CSF ow and cord tethering. If untethering issuccessful and CSF ow maintained, the syrinx will notbecome symptomatic and sizeable cavities will becomesmaller (Fig. 2).8,11,22,29,46,56,63,73Therefore, the presence ofsyringomyelia does not require additional surgical mea-sures.

Surgical Management: Untethering and Prevention ofRetethering

In the present study, untethering was considered suc-cessful, if all tethering components could be released asjudged by intraoperative assessment. This was achievedin 42 of 51 operations. In Group A, all untethering pro-cedures were successful with 2 patients with split cordmalformations treated early in the series undergoing tran-section of the lum in a second operation. Presently, bothuntethering the split cord and transection of the lum areperformed in a single procedure.26In Group B, untether-ing was successful in 22 (76%) of 29 operations. Htt-mann et al.30reported successful untethering proceduresin 82% of their 54 adult patients; they did not provideseparate analyses for subgroups.

Several features may be involved in the tetheringprocess in an individual patient. Not all of them can beidentied on MR imaging and some have to be looked forduring surgery.

Chances for successful untethering correlate withthe complexity of the malformation.44Therefore, patientswith complex malformations should be treated by sur-geons with considerable experience in the managementof these complex lesions.

In the simplest type of tethering (that is, for a tight -lum terminale), the cord can be released with transectionof the lum. With split cord malformations, the spinalcord is tethered at the site where either intradural mesen-chymal tissue and/or an epidural bony spur splits the cord.

TABLE 7: Clinical recurrence rates in patients with a

tethered cord

Group

Recurrence Rate (%)

5 Years 10 Years

A: tethered cord all

1st surgery

24

11

24

11

B: tethered cord hamartoma

all

1st surgery

complete untethering

partial untethering

secondary surgery

42

31

19

60

86

61

31

19

100

A & B: all patients

1st surgery

secondary surgery

no surgery

all

surgery recommended

22

78

21

47

22

100

21


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was performed, the clinical stabilization rate rose to 89%.In Group B, the corresponding rate for complete untether-ing in a rst operation was 81%. After incomplete unteth-ering in Group B, the clinical recurrence rate rose to 60%within 5 years. Revision surgeries for this group failedto stabilize the clinical course in the long term (Table 7)

(Figs. 6). The considerable worsening of the long-termprognosis in Group B, once a rst surgical attempt wasnot successful, places an enormous responsibility on thesurgeon conducting the initial surgery.

Comparing these data with pediatric series, one ndssimilar results with rates for symptomatic retethering re-ported between 10% and 26% and a trend for worse re-sults for more complex malformations.3,15,16,21,44,55,72In theirseries of 238 patients, Pang et al.61reported that 82.8% oftheir patients were free from neurological progression for16 years, which they attributed to their aggressive approachto lipoma resection. In an earlier study with partial lipomaresections, this rate had been higher34.6% for 10.5 years.Leaving a partially resected lipoma open to the subarach-

noid space was associated with a considerable risk for re-tethering and was probably the major cause of the poor re-sults after secondary operations in Group B patients in thepresent study as well as in other reports.5,16,21,60However,closing the lipoma capsule after partial resection, as de-scribed, may serve the same purpose, as suggested by thesimilar retethering rates of this study.

Comparison of Surgically and Nonsurgically TreatedPatients

We still lack precise information on the natural his-tory of tethered cord syndromes. Consequently, the con-troversy concerning prophylactic surgery of these lesionsis still unresolved. This debate started as early as 1918,

when Brickner9

suggested surgery to treat asymptom-atic infants in the hope of preventing future deteriora-tion. In a comparative study of operated and unoperatedconus lipomas, Kulkarni et al.45 reported follow-up re-sults in 2 groups comprising 53 asymptomatic patients:those obtained not surgically treated (data accrued since1994) and those prophylactically surgically treated (dataacquired between 1972 and 1994). According to theirKaplan-Meier analysis, the risk of deterioration within9 years was 33% for conservatively treated patients and46% for surgically treated patients. This difference wasnot statistically signicant, and the authors concludedthat there was no evidence for a prophylactic effect to jus-tify surgery of asymptomatic conus lipomas. Pang et al.,61however, observed a prophylactic effect in asymptomaticchildren who underwent surgery. After 16 years, 98.4% ofthe patients remained neurologically intact.

In the present series, surgery was offered to 60 of 85patients because of pain and/or neurological symptomsthat were either progressing or considered improvablewith surgery. The postoperative clinical recurrence ratesin Groups A and B were 11% and 31%, respectively, after10 years in cases in which this was the initial surgery(Figs. 6BD). For patients in whom surgery was not per-formed, 1 of 16 patients in Group A and 4 of 17 in GroupB suffered neurological progression. Of these 5 patients,just 1 in Group B had not been advised to undergo surgery

because progressive symptoms were absent at presenta-tion. In that case, the clinical deterioration was related tosurgical morbidity incurred at another institution and notto the natural history. The other 4 patients had refusedsurgery despite neurological symptoms and a recommen-dation to undergo surgery; their neurological symptoms

deteriorated further. Even the majority of those patientswho had presented with neurological symptoms reporteda stable clinical situation throughout follow-up. The cor-responding clinical recurrence rates for all nonsurgicallytreated patients combined was 21% after 10 years and therate increased to 47% in 5 years, if calculated separatelyfor patients with a recommendation for surgery (Fig. 6C).This rate is more than twice that in patients who under-went surgery for the rst time with successful untetheringbut just missed the level of statistical signicance.

Do these results have implications for the manage-ment of asymptomatic children? This study implies thatnot all asymptomatic children will become symptomat-ic. Some patients in this study had been asymptomatic

even throughout their adult life when symptoms nallyarose with advancing age. How many and which patientswill develop neurological problems remain questions notknown with certainty. Once patients have reached adult-hood, the clinical course appears to be more benign thanit does in symptomatic children, as indicated by the lownumber of adult patients with severe decits and the sig-nicant proportion of them refusing surgery: 32% in thisstudy and 12 of 20 patients in a report by Dz et al.17

Thus, prophylactic surgery in asymptomatic patientsrequires an extremely high standard of treatment for jus-tication. The results of this study do not support a rec-ommendation for prophylactic surgery in asymptomaticpatients with tethered cord syndromes. The essential pre-conditions for optimal management are an early diagno-sis and close clinical monitoring to be able to interveneas soon as neurological symptoms appear or progress.27,65

Conclusions

The present study demonstrates that complete un-tethering in symptomatic adult patients with tetheredcord syndromes undergoing surgery for the rst timeimproved pain and prevented further neurological pro-gression in 81%89% of patients. In 47% of symptomaticpatients who refused an operation, further progression ofthe decit occurred. On the one hand, these rates indi-cate that untethering has a prophylactic effect in symp-tomatic adults with a tethered cord. On the other hand,

this study also shows that not every adult patient requiressurgery. No progressive clinical worsening was observedin patients without neurological symptoms or in those inwhom other factors such as degenerative spinal diseaseswere considered responsible for the clinical condition.

For an adult patient with a tethered cord only (thosein Group A, for example), surgery should be recommend-ed as soon as neurological symptoms are present or painattributable to the tethered cord has appeared. For adultpatients with complex malformations (those in Group B,for example), surgery should be advised as soon as symp-toms progress or pain has become severe. Secondary op-


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erations in patients with complex malformations shouldbe undertaken in exceptional cases only because surgicalmorbidity is higher and a long-term benet less likely.

The long-term prognosis appears to be related to therate of symptomatic retethering. All intraoperative stepsshould be planned and executed carefully to minimize

this risk.

Disclosure

The author reports no conflict of interest concerning the mate-rials or methods used in this study or the findings specified in thispaper.

Acknowledgment

The author expresses his sincere gratitude to Madjid Samii,M.D., former chairman of the neurosurgical clinic at Nordstadt Hos-pital in Hannover, Germany, for his continuous support of this work.

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Manuscript submitted July 12, 2010.Accepted April 18, 2011.Please include this information when citing this paper: pub-

lished online May 20, 2011; DOI: 10.3171/2011.4.SPINE10504.Address correspondence to: Jrg Klekamp, M.D., Christliches

Krankenhaus, Department of Neurosurgery, Danziger Strasse 2,49610 Quakenbrck, Germany. email:[email protected].

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