In this article, the case history, clinical presentations, imaging findings, surgical management, pathology and clinical outcome of Currarino syndrome were described for seven pediatric patients.
The expressivity of this triad is variable, and the clinical manifestations comprise a complex spectrum. As reported in other countries, patients with Currarino syndrome present with an ARM, which is usually in the form of an anorectal stenosis . In this study, a perineal fistula without an anus was the most prevalent presentation. Constipation is the most commonly reported symptom . The syndrome can present as an imperforate anus at birth and intractable constipation due to anorectal stenosis or extrinsic compression by a presacral mass. The presacral mass can result in urinary incontinence, sacral anesthesia, paraesthesia of the lower extremities, disturbance of anal sphincter control, headache when exercising, or acute or recurrent meningitis [5,6]. Other symptoms include recurrent urinary tract infections, nausea, lumbar pain, and chronic anal fistula . Among our seven cases, the twin patients presented with urgent intestinal obstruction due to an imperforate anus with a perineal fistula at birth. Four of the other five patients suffered from constipation even after anoplasty, including one patient (case one) with symptoms of urinary retention and constipation and another patient (case four) who suffered from urinary infection due to left VUR.
Currarino syndrome is related to mutation of the MNX1 gene, previously called the HLXB9 gene. Mutations in the coding sequence of the MNX1 gene have been reported in nearly all familial cases and in approximately 30% of sporadic cases . The identical twin patients in this study and their parents underwent genetic testing and initial pedigree screening. No genetic mutations of MNX1 or any other defective genes were found. The other five patients did not undergo genetic testing.
The routine and necessary imaging approach includes a radiograph of the sacrum, presacral US and spinal MRI. Patients with an ARM must undergo multiple radiologic examinations, including vertebral radiographs, to evaluate vertebral anomalies, abdominal and pelvic US to evaluate urogenital abnormalities, an MRI of the pelvis and spine to evaluate the complexity of the malformation, and a colostogram to observe the colon and underlying fistulous tract from the rectum to either the bladder or urethra . In addition to these imaging examinations, a urodynamic examination is necessary in patients with urodynamic dysfunction .
Among neural tube defects (NTD), a tethered cord is commonly found to be associated with an anterior meningocele . All patients with anterior meningoceles in this group presented with a tethered cord, as confirmed by MRI. Urologic involvement may be characterized by a duplex ureter, horseshoe or duplex kidney, VUR, dysplastic kidneys, or hypospadias. Therefore, the urinary tract should be examined in all patients with Currarino syndrome by US, and in cases of radiologic or clinical suspicions of VUR, an MCU should be performed . Gynecologic malformations, including a bicornuate uterus, septate vagina, and bifid clitoris, were also noted [13,14]. Three girls (50%) had gynecologic malformations. Other associations of Currarino syndrome with Hirschsprung’s disease (HD), Down’s syndrome, and cranial and central nervous anomalies have been described [13,15]. One of the twin patients (case three) in our study was diagnosed with hydrocephalus and received a ventriculoperitoneal shunt at four months of age in a local institute. In the case of constipation, a rectal suction biopsy has been suggested to exclude HD or other dysganglionoses . Two patients (cases one and five) suffered from intractable constipation and were diagnosed with a dilated colon after anoplasty; HD was excluded by operative pathology.
The management of Currarino syndrome generally consists of treatment of ARMs and the presacral mass. A presacral mass may be approached surgically through a posterior sagittal approach attained by an incision from the sacrum to the anus . The prone position is the standard approach for posterior sagittal anorectoplasty(PSARP) in males; however, in females, the supine position can be used as an alternative . Meanwhile, the supine lithotomy position provided better access to explore the presacral space. In this study, a limited sagittal route was performed. The patient was put in lithiotomy position, and the mass was attained by an incision from the anus to the point large enough to explore, which usually in front of the sacrum. This route allowed for the excision of the presacral mass with a smaller incision, followed by dural closure and anoplasty. In cases one and five, after the removal of the presacral mass and the closure of the meningocele pedicle, the dilated descending colon and rectum were excised due to myofibrosis and hypoperistalsis, followed by anastomosis of the remaining colon and anus. The patients in cases one, two and five underwent insufficient treatment before they came to our department; therefore, excision of the presacral mass and repeat anoplasty were performed. The patient in case three came to remove the presacral mass after an anoplasty elsewhere. The patient in case seven came for severe postoperative complication-- a buttock sinus tract was found and excised then. For patients with anoplasty failure, the limited sagittal route allows for a good cosmetic result with a minimal incision and a favorable resolution of the coexisting problems. In this group, anal dilation for 3 to 6 m was conducted after anoplasty to prevent stenosis.
Palliative surgery is initially performed in infants born with an ARM to divert the colon and allow the patient to mature before definitive surgery. The initial palliative surgery of an imperforate anus includes a colostomy to allow the enteric contents to evacuate while an additional stoma is created for the distal colon . Cases two and three underwent colostomy after birth for intestinal obstruction due to an imperforate anus. Four of the other patients received ileostomy in our department after removal of the presacral mass and anoplasty to prevent CNS infection and ensure healing of the incision. We prefer to use the terminal ileum for the stoma because it is easier to perform without disturbing the pelvic cavity. Meanwhile, it is also easier to be closed after healing of the incision.
Pathologically, the presacral mass that accompanies Currarino syndrome may consist of a teratoma, a hamartoma, a neurenteric cyst, an anterior meningocele or a combination of these four entities. Dermoid cysts, lipomas, leiomyosarcomas, yolk sac tumors and carcinoid tumors have been described as well. Currarino syndrome may be occasionally associated with epidermoid cysts. However, the most frequent pathologies described are anterior sacral meningoceles and teratomas . Presacral meningoceles are the most common entity (60% of patients) . Mature presacral teratomas were the prevalent presentations in these seven cases, and five of them had connection with the spinal canal. That is also the reason a neurosurgery expert should be included in the multidisciplinary team. No malignant mass was recorded in this group. However, an oncologist is always needed to made proper protocol especially when malignancy is supposed there.
During follow-up, particular attention should be paid to bowel and bladder function, and constipation, if present, should be treated . All patients are thriving with excellent cosmetic and functional results at follow-up apart from urinary incontinence in one patient with a neurogenic bladder. The patient with VUR received antibiotic prophylaxis. If surgical treatment of VUR is indicated, it should be performed last. For such patients, further urologic and neurologic counseling are necessary.
A delayed or missed diagnosis of a presacral mass is common when there is no or limited experience in detecting and treating these cases. A lack of proper imaging leads to misdiagnoses and insufficient repair, requiring reoperation. Four patients in this study presented with unfavorable ARM operation results and an undiagnosed presacral mass. One of the twins included in this study was diagnosed in the neonatal department of our institution but did not receive treatment for the presacral mass when the ARM was treated due to a lack of experience. Case seven suffered from severe CNS infection due to iatrogenic injury to the rectum and lack of colostomy during removal of the mass in the oncology department. For such patients, the presacral mass is adherent to the posterior wall of rectum and usually has a connection with the spinal canal, a diverting colostomy or ileostomy is necessary. Regarding the complains and rough courses of most of the patients in this study, a multidisciplinary team of general surgey, neurosurgery, oncology and urology is necessary for optimal treatment of children with Currarino syndrome.