Beer Sheva, Israel

Definition: Herniation of the meningeal sac into the extra peritoneal pelvic region through a congenital defect in the sacrum¹.

Pathology: The herniated sac is composed of two layers: the outer dural sac, and the inner arachnoid membrane. The sac contains cerebro-spinal fluid with no neural elements. It also called Type 1 extradural meningeal cyst (Occult sacral meningocele) according to Nabors M.C et. al’s classification².

Incidence: The incidence of myelomeningocele varies according to geographical origin. From 3-6:10,000 live births in Japan and Scandinavia 30:10,0000 and 32-41:10,000 live births in England and Wales⁴. Sacral meningoceles represent approximately 20% of all meningocele⁵.

183 cases of anterior sacral meningocele were reported in the postnatal literature from 1837 to 1991. Medline search from 1990 to April 2000 revealed other 24 cases.

anterior sacral meningocele involve mostly females with reported incidence of 79%⁶

It represents 2.8% of all presacral tumors in females⁷. No case of prenatal diagnosis was reported.

Inheritance: The genetic inheritance pattern has not been ascertained. An X-linked dominant pattern was proposed⁸. In most cases with family recurrence, autosomal dominant transmission is suggested.

The cytogenetic defect site was reported to be linked to the HLA₉,₁₀ in a location, 7q36, which also contain a gene for holoprosencephaly¹¹. On the other hand, Chatkupt et al.¹² could not confirm the HLA region as the location for the sacral defect anterior meningocele in members of five generation family with this disorder.

Etiology:¹³

1. Congenital:
   • Sacral bone defect
   • Proliferation of arachnoid
   • Connective tissue disorder (Marfan)
2. Degenerative : Ischemic lesion
3. Traumatic : Nerve root avulsion or hemorrhage
4. Iatrogenic : During surgery

Case report of presacral cystic mass  

A 25-year-old woman, G₃ P₂, was referred for a routine second trimester sonographic evaluation, at 21 weeks gestation. The woman had previously two normal pregnancies which ended in term spontaneous birth of two normal infants.

Her family history of malformations or genetic disorder was unremarkable. The “triple screen test “ blood test values were in the normal range, with calculated risk for Down syndrome inferior to her age-correlated risk.

On sonographic examination, a cystic mass was observed positioned between the sacral spine and the bladder. The mass displaced the bladder and seemed to be a part of it. Ureterocele, intra vesical septum or persistent cloaca were suspected at this point of the examination (Fig. 1, 2).

Fetal pelvis with full bladder and presacral cystic mass (fig. 1, 2)

After a complete emptying of the bladder, and using the color Doppler for the visualization of the two perivesical umbilical arteries course, the cystic mass was identified as a separate mass localized at the anterior aspect of the sacral spine. The cyst measured 20.4 by 12 mm in transverse section of the pelvis, and 9 by 8 mm in a longitudinal section (Fig. 3, 4). It had a round shape at its anterior part and became a digit like projection as it approached the ossification center of the vertebra on its right side. This hypoechogenic tubular prolongation was seen in contiguity with the spinal canal in transverse section (Fig. 3, 4, 6). On transvaginal scan a bony defect at this level was suspected (Fig. 2).

Presacral cystic mass (Fig. 3, 4)

Longitudinal view: spine and pelvis. (Fig. 5.6).

The fetal lower limb movements and tonus were normal. The bladder manifested good function with regular filling and emptying in two cycles at about 40 minutes interval. The fetal biometry agreed with the gestational age according to the last menstrual period and ultrasound dating in the first trimester. No other structural abnormality was noted excluding mild unilateral renal pyelectasis of 5 mm in the antero- posterior diameter. The karyotype was normal.

The woman was counseled about the various diagnostic possibilities with special attention to the unpredictable prognosis concerning the possible of sacral meningocele and sacrococcygeal teratoma. The couple decided to terminate the pregnancy.  

Histology  

Unfortunately pathologic examination was far from being optimal. Only a retrospective examination indicated that the presacral sac membrane was of meningeal origine.

The slides which demonstrated, according the pathologist, clearly this origin, were also lost.  

Radiology  

Was not optimal plain X-ray, and did not demonstrated the classical “scimitiar sign” or any sacral bony defect.

Clinical presentation: Clinically the symptoms are local, and related to the pressure exercised on the adjacent organs: rectum, bladder, genital organs and sacral nerve roots.

Aside from meningitis due to rupture/infection of the herniated sac, no central neurologic damage like hydrocephaly or Arnold Chiari malformation were reported.

The symptoms appear usually in the second to third decade of life. In man it may appear earlier in the first decade¹². Abdominal pains, constipation, urogenital (urinary retention or incontinence), gynecological (dysmenorrhea, dyspareunia) and neurological (low back pain, radiation to the legs and meningitis) symptoms were reported in more than two thirds of the cases.

Abdominal, neurological, and urogenital symptoms are the most common and present in 70 % 30% and 27% respectively, of all symptomatic patients¹.

Diagnosis

X Ray Plain Radiography

A unilateral sickle shape distortion of the sacral bone – The “ Scimitar sacrum” - is considered pathognomonic. This sign is not presented in all cases, for example, when the defect is in the midline, or represents only a widened foramina like in Marfan Syndrome and neurofibromatosis^{14, 15}.

Myelography

Was, theoretically, useful to distinguish between meningocele and other neuronal cystic masses not connecting with the arachnoid space¹⁶.

Oil based or even water-soluble contrast material may fill slowly, partially, or not at all the herniated sac. Narrow stalk or adhesions may prevent or delay the passage of the contrast material^13,14.

Ultrasound

Can be diagnostic, but is limited in visualizing the stalk. It can identify extension through enlarged foramina^14,15, and the content of the presacral mass.

CT with contrast enhancement

Has also limited diagnostic capacity in visualization of the stalk^15,17.

MRI

Is the diagnostic method of choice, and has the advantage of defining tissue planes, useful in planning the surgical approach^17,18.

Differential diagnosis (Presacral cyst)

1. Sacrococcygeal Teratoma: The incidence varies between 0.25-0.3:10,000     births^19,20. Only 10% of all the sacrococcygeal teratoma are entirely intraabdominal (Type IV). In this group, only 15% are entirely cystic²¹.
2. Persistent cloaca
3. Tumor: Dermoid, lipomas, neuroblastoma.
4. Neuroectodermal cyst²².
5. Sacral meningeal cyst: Nabors et. al. Classification²
   • Extradural cyst without spinal nerve root fibers
   • Meningeal / Arachnoid cyst
   • Occult Sacral Meningocele.
   • Extradural cyst with spinal nerve root fibers.
   • The perineural (Tarlov’s ) cyst¹⁶ is located along the nerve root and      represents extension of the dural and arachnoid¹³.
   • “Spinal nerve root diverticulum”
   • Intradural Cyst (Intradural arachnoid cyst)
   • A combination of all 3 types (anterior sacral meningocele , perineural cyst and intrasacral meningeal cyst) in one case was reported by North et al.¹³.
6. Gastro intestinal tract:
   • Rectal dilatation caused by anorectal atresia, Hirschprung’s Disease or meconium plug syndrome.
   • Bowel duplication
   • Meconium pseudo cyst

1. Ovarian cyst
2. Pelvic kidney cyst

Associated anomalies

The Currarino syndrome: anterior sacral meningocele was reported to be associated with other malformations in the so-called Currarino syndrome or triade. It includes anorectal malformations, sacral bony defect, and presacral mass. The etiology is unknown, but recent report of an association with caudal split cord, suggested an embryo genetic mechanism originating in a failure of dorso- ventral separation of the caudal eminence from the hint gut endoderm during late gastrulation³⁰.

A review of the literature up to 1996 revealed 211 cases of complete or incomplete Currarino syndrome²³. Medline research until April 2000 revealed other 16 cases.

Complete anorectal malformations, sacral bony defect, and presacral mass was reported in 48 (22.7 %) cases. Other 74 (36.9 %) presented with only sacral defect and presacral mass and 89 (42.2 %) presented with only one or two of the Currarino triad.

The anterior sacral mass was reported to be an anterior meningocele in 68% of the cases, whereas, benign teratoma was reported in 18% of the cases of Lee et al. 11 cases series showed approximately the opposite percentage relations²⁹.

Other type of presacral mass included:

• malignant teratoma in two cases (0.9%),
• leiomyosarcoma in one case (0.47%),
• dermoid cyst in 8 cases ( 3.8%),
• lipoma in 5 cases (2.3%),
• neurofibromatosis in 3 cases ( 1.4%),
• hamartoma in 2 cases ( 0.9%),
• enteric cyst in 2 cases (0.9%) and
• unclassified tumor in 10 cases (4.7%).

Rarely, anterior sacral meningocele and presacral teratoma coexist in the same patient. Only six such cases have been reported until 1989²³.

Anterior sacral meningocele associated with hemisacral dysgenesis were described also as subtype of caudal dysgenesis, a rare syndrome occurring in 0.14% of the children. 24

Marfan syndrome - anterior sacral meningocele was reported to be associated in 21% of the cases compared to around 200 cases among the general population28.

The etiology is presumed to be connected to the disorder of collagen biosynthesis and structure at the dural level^{15, 28}. Only 8 cases were reported in the literature until 1992¹⁵ with only other 3 case reported until April 2000.

Treatment:  Surgery is the treatment of choice because there is no spontaneous regression. Conservative management is associated with 30% mortality rate mostly due to meningitis²⁷.

The posterior approach, transsacral or sagittal²⁵, is the preferred one because of the lower complication rate. The anterior laparotomic approach has a high morbidity and mortality (22%) due to infections and fistula formation.

For the same reason transvaginal and transrectal puncture are contraindicated (including for diagnostic purpose)¹.

Recently an endoscopic approach was suggested as a easier and shorter alternative^15,26.

Prognosis

Prior to 1960 mortality rate from surgery was 40%²⁷. It decreased to 4% with the introduction of the posterior approach¹.

Pregnancy and anterior sacral meningocele

Only 14 cases of anterior sacral meningocele in pregnancy were reported in the literature. Three (22%) of them died due to rupture of the meningeal sac during labor⁶.

Cesarean section is considered the only mode of delivery.

References

1)         Andersen C and Tange M. Anterior sacral meningocele. case report. 1990, Acta   Chir. Scand. 156; 808 – 811.

2)         Nabors M.C et. al Update assessment and current classification of spinal meningeal cysts. 1988, J. Neurosurg. 68; 366 - 377.

3)         Hagelstone J. H. et.al disability in children with myelomeningocele. A nordic study. 1989, Acta Pediatr. Scand. 78; 721 – 727.

4)         Nyberg DA, Mack. LA, Langer JC. The spine and neural tube defects In  Nyberg DA, Mahony BS, Pretorius DH (ed) Diagnostic Ultrasound of Fetal Anomalies : text and atlas, 1990, pp. 182-187 (St. Louis Mosby Year Book).

5)         Brinker M.R et.al. Myelomeningocele at at the sacral level. Long term outcomes in adults. 1994, J. Bone and Joint surg. 76-A ; 1293 – 1300.

6)         Kofinas AD et.al.. Anterior sacral meningocele in pregnancy. 1987, Obstet. Gynecol. 69 : 441- 4.

7)         Lee R.A and Symmonds R.E Presacral tumors in the female : Clinical presentation, surgical management, and results. 1988, Obstet. Gynecol. 71 ; 216 – 220.

8)         Cohn J and Bay – Nielsen E : Heredity defects of of the sacrum and coccyx with anterior sacral meningocele. 1969, Acta Pediatr. Scand. 58 ; 268 – 274.

9)         Welch JP and Alterman K. The syndrome of caudal dysplasia : A review, including etiologic considerations and evidence of heterogeneity.1984, Pediatr. Pathol. 2 ; 313 - 327.

10)       Hardwick R. J. et.al. Partial sacral agenesis with constipation : a report of one  family. 1992, J. Paediatr. Child Health ; 28: 328 – 30.

11)       Lynch SA et.al. A gene for autosomal dominant sacral agenesis maps to the holoprosencephaly region at 7q36. 1995, Nature Genetics, 11 : 93 - 95 (letter).

12)       S. Chatkupt et. al.. Linkage analysis of a candidate locus (HLA) in autosomal domonant sacral defect with anterior meningocele. 1994, Am. J. Med, Genet. 52: 1 - 4.

13)       North R.B et.al. Occult, bilateral anterior sacral and intrasacral meningeal and perineurial cysts : Case report and review of the literature. 1990, Neurosurgery; 27 : 981 – 986.

14)       McCreath G. T. and Macpherson P. Sonography int diagnosis and management of anterior sacral meningocele. 1980, J. Clin. Ultrasound 8 ; 133 – 137.

15)       Raftopoulos M.D et.al. Endoscopic cure of giant sacral meningoceleassociated with Marfan’s Syndrome : Case report. 1992, Neurosurgery 30 ; 765 – 768.

16)       Tarlov I. M. Spinal perineurial and meningeal cysts. 1970, J. Neurol. Neurosurg. Pshychiatry 33 ; 833.

17)       Chamaa MT and Berney J.Anterior Sacral Meningocele :; Value of magnetic resonance imaging and abdominal sonography. 1991, Acta Neurochir (Wien) 109 : 154 -157.

18)       Fitzpatrick M.O and Taylor W.S Anterior sacral meningocele associated with rectal fistula. case report and review of the literature. 1999, J Neurosurg (Spine 1) 91 ; 124 – 127.

19)       Pantoja E et. al. Retro peritineal teratoma :historical review. 1976, J. Urol. 115; 520 - 523.

20)       Altman RP et. al. Sacrococcygeal Teratoma : American Academy of 1973, Pediatrics Surgical Section Survey. J. Pediatr. Surg. 389 -398.

21)       Brem H. et.al. Neonatal diagnosis of a presacral mass in the presence of congenital anal stenosis and partial sacral agenesis. 1989, J. Pediatr. Surg. 10 ; 1076 - 1078.

22)        BloechleM et.al. Neuroectodermal cyst may be a rare differential diagnosis of fetal sacrococcygeal teratoma : first case report onf prenatally observed neuroectodermal cyst. 1996, Ultrasound Obstet. Gynecol., 7 ; 64 - 67.

23 )     Kochling J et.al. The Currarino syndrome - Hereditary transmitted syndrome of anorectal, sacral, and presacral anomalies. Case report and review of the literature. 1996, Eur.J.Pediatr.Surg. 6 ; 114 -119.

24)     Welch J P and Alterman K The syndrome of caudal dysplasia : a review,  including etyologic considerations and evidence of heterogeneity 1984, Pediatr Pathol. 2 ; 313 – 327.

25)     Somuncu S. Ariturk E. Iyigun O. Bernay F. Rizalar R. Gunaydin M. and Gurses N. (1997) A case of anterior sacral meningocele totally excised using the posterior sagittal approach. J. Pediatr. Surg. 32; 730 - 732.

26)     Clatterbuck RE et.al. Laparoscopic treatment of anterior sacral menigocele. Case illustration. 2000, J. Neurosurg. (spine 2) 92 ; 246.

27)     Amacher Al et.al. anterior sacral meningocele. 1968 surg. Gynecol. Obstet. 126 ; 986 – 994.

28)     Pyeritz RE et.al. Dural ectasia is a common feature of the Marfan Syndrome. 1988, Am. J. Hum. Genet. 43 ;726 – 732.

29)     Lee SC et.al. Currarino Triade : Anorectal malformation, sacral bony abnormalities, and presacral mass – a review of 11 cases. 1997, J. Pediatr. Surg. 32 ; 58 –61.

30)     Dias MS and Azizkhan RG. A novel embryogenetic mechanism for Currarino’s triade : Inadequate dorsoventral separation of the caudal eminencefrom huntgut endoderm 1998, Pediatr. Neurosurg. 28 ; 223 –229.