Split cord malformation

Developmental Malformations

Updated 08.18.2025
Released 12.12.1994
Expires For CME 08.18.2028

Split cord malformation

Authors: Marc Beaudin MD, Alcy R Torres MD FAAP

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Editor: Alcy R Torres MD FAAP

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Split cord malformation

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Introduction

Overview

Split cord malformations, although rare, can cause progressive neurologic impairment if not properly identified and surgically treated. These malformations can be associated with tethered cord, congenital scoliosis, and other spinal dysraphisms. In this article, the authors describe its various associated signs and symptoms, imaging modalities best used for its diagnosis, surgical treatment options, and prognosis. The authors also provide updated information about the etiology, evaluation, and treatment of this interesting group of disorders.

Key points

	• Split cord malformations are associated with spinal dysraphisms, congenital scoliosis, and tethered cord.
	• Split cord malformations usually present in childhood but can present in adulthood, especially in patients with the above conditions who have new-onset neurologic symptoms.
	• Split cord malformations can be missed by routine imaging, especially if that imaging was done in the past with older technology; thus, a prior normal scan does not rule-out this condition.
	• Early identification and surgical correction can arrest or improve neurologic symptoms.

Historical note and terminology

Diastematomyelia was first described by Ollivier in 1837 and refers to a congenital malformation characterized by a longitudinal splitting of the spinal cord into at least two distinct hemicords. The term originates from the Greek diastema (cleft) and myelos (marrow or medulla). Typically, the split is caused by an intervening mesenchymal structure, such as bone, cartilage, or fibrous tissue. This entity was historically distinguished from diplomyelia, which implies a duplication or a twinning of the spinal cord.

Traditionally, the distinction between diastematomyelia and diplomyelia was based on differing embryological mechanisms (26). Diastematomyelia was thought to arise from a disruptive embryological process involving the intrusion of abnormal mesenchymal tissue into the developing neural tube. Clinically, diastematomyelia has historically been associated with a high likelihood of progressive neurologic deterioration (49; 20), prompting early recommendation for neurosurgical intervention (14; 15). In contrast, diplomyelia was attributed to a localized duplication phenomenon during early development.

Pang challenged this dichotomy in the early 1990s by proposing a unified embryogenetic model and introducing the term “split cord malformation” to encompass both conditions, with a revised classification based on anatomical and pathological features rather than presumed embryological origin (38; 38). Under this system, split cord malformation type I (diastematomyelia) is defined by two hemicords, each within its own dural tube, separated by a rigid osseocartilaginous septum, whereas split cord malformation type II (diplomyelia) features two hemicords within a single dural tube, separated by a nonrigid fibrous or fibrovascular septum.

In addition to split cord malformations, three spinal dysraphisms warrant clarification: split notochord syndrome, rachischisis, and myeloschisis. Split notochord syndrome is a rare, severe developmental anomaly in which there is a persistent communication between the endoderm and ectoderm due to abnormal notochord development, resulting in combined spinal, vertebral, and gastrointestinal anomalies. Rachischisis refers to a profound malformation characterized by a continuous, longitudinal cleft of the vertebral column and spinal cord, resulting from complete failure of neural tube closure during early embryogenesis, that extends along a substantial part or entirety of the spinal axis. Myeloschisis, by contrast, represents a localized variant of open spina bifida. It is defined by the persistence of the neural plate without proper folding or closure, leaving the ependymal surface of the spinal cord exposed to the external environment without any intervening skin or meningeal covering.

Clinical manifestations

Presentation and course

Split cord malformations are commonly asymptomatic. When symptomatic, the clinical manifestations of split cord malformation types I and II are heterogeneous but can be categorized into cutaneous stigmata, orthopedic deformities, and neurologic deficits.

Cutaneous manifestations. The most common cutaneous manifestations of split cord malformation in both pediatric and adult symptomatic patients are midline lumbosacral or thoracolumbar hypertrichosis (hairy patch or faun tail), midline dimples, subcutaneous lipomas, dermal sinus tracts, capillary hemangiomas, and other vascular nevi. Hypertrichosis is the single most frequent finding, present in up to 79% of adults and 32% of children with split cord malformation, and the faun tail variant is particularly associated with split cord malformation type I (18). A midline dimple with a meningocele-like lesion in neonates may indicate underlying split cord malformation type I with a dorsal bony spur, which is particularly relevant for surgical planning (16). Other markers, such as silky down, nevi, and skin tags, may also be seen.

Orthopedic deformities. The most common presenting deformities in patients with split cord malformation are scoliosis and tethered spinal cord syndrome (28). Spinal deformities may include scoliosis, kyphoscoliosis, and lower limb anomalies—most frequently congenital talipes equinovarus followed by unilateral limb shortening (28). Common vertebral anomalies include spina bifida, meningocele, butterfly vertebra, hemivertebra, and fused or absent ribs. Additional associated abnormalities include syringohydromyelia and Chiari malformation (45). In a retrospective series of 266 patients with congenital scoliosis and coexisting split cord malformation, 83.5% had multiple malformations (13). Compared with patients with type II malformations, those with type I had a higher prevalence of multiple malformations, mixed vertebral anomalies, and longer segments of spinal involvement. Rib anomalies were present in 62.8% of cases, and multiple intraspinal anomalies were frequently identified in association with congenital scoliosis and split cord malformations.

Neurologic deficits. Split cord malformation rarely presents with truly acute neurologic deficits unless there is a superimposed event, such as trauma or acute tethering. Most symptomatic patients experience a chronic, insidious progression of symptoms, with the rate of deterioration influenced by the degree of cord tethering, the presence of associated anomalies, and the age at which the malformation becomes symptomatic (06; 22; 36). In both types, the evolution from mild to advanced disease is marked by increasing neurologic impairment, often with stepwise or slowly progressive worsening rather than abrupt changes. On examination, lower extremity weakness (often asymmetric), muscle atrophy, abnormal deep tendon reflexes, and orthopedic deformities are the most common physical findings. The limited ability of young children to report sensory disturbances and the frequent misattribution of bladder or bowel incontinence to delayed toilet training may contribute to delayed clinical recognition. Palpable bony spurs may be detected, especially in the lumbar region (30). Rarely, split cord can occur in the cervical region, where the signs and symptoms affect the arms and hands in addition to the legs, bladder, and bowels (28; 34). This is occasionally associated with Klippel–Feil syndrome (28; 34) and other complex central nervous system malformations (41; 03).

Presentation in pediatric patients. In a retrospective series of pediatric patients with split cord malformation type I, common manifestations of symptomatic patients included motor dysfunction (61%), congenital neurologic deficits (29%), scoliosis or kyphoscoliosis (63%), foot deformities, limb length discrepancies, and cutaneous markers. The onset of symptoms is often early, usually developing progression of congenital deficits or new deficits by the age of 2 years, underscoring the need for early recognition and intervention (06; 30; 36). In pediatric split cord malformation type II, the clinical picture is similar but generally milder. Motor deficits, sensory disturbances, and pain are common, but the prevalence and severity of orthopedic deformities and cutaneous stigmata are somewhat lower than in split cord malformation type I. Bladder and bowel dysfunction are less frequent and typically occur in more advanced cases (02).

Presentations in adult patients. In adults, split cord malformation types I and II typically present insidiously, with a predominance of pain and gradually progressive neurologic deficits. In an adult series (n = 94; 35 with split cord malformation type I and 59 with split cord malformation type II), radicular pain was the predominant presenting symptom, followed by progressive motor and sensory impairment (23). Pain is usually localized to the back or radiates to the lower extremities, often associated with paresthesia. Pain is commonly reported as a dull, localized discomfort over the affected region of the back or as poorly localized dysesthetic pain involving both lower limbs. In some cases, patients describe a “boring” or “searing” pain in the perineal and anal regions. Motor weakness, gait disturbance, and sphincter dysfunction are also reported, although less frequently than in pediatric populations (22; 23). Orthopedic deformities, such as scoliosis, are uncommon presenting features in adults, likely reflecting earlier detection and management in childhood. Cutaneous stigmata are rare, either overlooked or diminished with age. Neurologic examination may reveal lower extremity weakness, muscle atrophy, abnormal reflexes, and sensory loss in a dermatomal or non-dermatomal distribution. Gait abnormalities and signs of upper or lower motor neuron involvement may be observed, depending on the level and extent of the split (22; 23).

Clinical vignette

A 6-year-old girl presented with fatigue when walking distances greater than one block. Examination revealed lumbosacral hypertrichosis with overlying capillary hemangioma, mild bilateral ankle dorsiflexor weakness, extensor plantar responses, and lower extremity hypertonia and hyperreflexia.

She also had moderate scoliosis; spinal radiographs demonstrated lumbar hemivertebra. MRI showed a thickened filum terminale and split cord malformation with a lumbar osseous septum. Urodynamic study showed evidence of bladder instability with upper motor neuron features.

Surgical exploration confirmed tethering of the bony septum. The septum was excised, and the filum terminale was sectioned. Postoperatively, neurologic status remained stable, with improved bowel and bladder function. The final diagnosis was split cord malformation type I associated with tethered cord.

Biological basis

Etiology and pathogenesis

Split cord malformations are typically nonsyndromic sporadic anomalies.

Normal development. In normal embryonic development, the notochord, derived from endoderm, functions as the axial organizer, inducing the overlying ectoderm to form the neural plate, which subsequently invaginates to create the neural tube—the precursor of the spinal cord (38; 21). The notochord and neural plate are central to axial patterning, regulated by key signaling pathways, including Sonic hedgehog (Shh), Wnt, Notch, and Hox/Cdx genes (21). Disruption of these pathways can result in abnormal neural tube closure and vertebral formation, as observed in other neural tube defects and congenital vertebral malformations. The coordinated development of the spinal cord and vertebral column depends on interactions between neural and mesodermal tissues mediated by bipotent neuromesodermal progenitors.

Pathogenesis. The most widely accepted model for the pathogenesis of split cord malformation is the unified theory of embryogenesis, originally proposed by Pang and colleagues and supported by subsequent clinical, radiological, and pathological evidence (38). This theory posits that split cord malformation arises from a single embryological error during gastrulation, typically between days 18 and 21 of gestation, involving the formation of an accessory neurenteric canal—an abnormal midline connection between the yolk sac and amnion across the embryonic disc. This canal develops due to aberrant adhesions between ectoderm and endoderm, giving rise to an endomesenchymal tract that bisects the notochord and neural plate. Mesenchymal cells migrate and condense between the split neural plate and notochord (21), and the fate of this tract determines the split cord malformation type: chondrification or ossification yields a rigid osseocartilaginous septum with separate dural sacs (type I), whereas persistence as a fibrous band results in a nonrigid septum with both hemicords in a single dural sac (type II) (38; 32; 21).

The unified theory is further supported by the frequent association of split cord malformation with other midline anomalies, such as neurenteric cysts, dermoid cysts, and vertebral segmentation defects, consistent with the pluripotent origin of the cells forming the accessory canal and tract (47). The occurrence of composite split cord malformations, whereby both types are present at different spinal levels in the same patient, and rare intermediate forms (type 1.5) supports the concept of a developmental continuum rather than entirely distinct pathogenic mechanisms (32).

Genetics. Genomic studies have identified several candidate genes and pathways implicated in the pathogenesis of split cord malformation, particularly in the context of congenital vertebral malformations that frequently co-occur with split cord malformation. Exome and genome sequencing in large cohorts have revealed significant enrichment of ultra-rare variants in genes, such as ITPR2, TBX6, TPO, H6PD, and SEC24B, which are involved in notochordal development of somites (54). Single-nucleus RNA sequencing of human embryonic spines has demonstrated that these genetic signals are enriched in the notochord during early development, supporting a mechanistic link between these genes and the pathogenesis of spinal malformations, including split cord malformation (54). However, no single gene mutation has been definitively linked to isolated split cord malformations, and the condition is considered to have a polygenic and developmental complexity.

Syndromic forms of split cord malformation have been described, particularly in association with spondylocostal dysostosis, a disorder characterized by multiple vertebral segmentation defects and rib anomalies. Spondylocostal dysostosis is caused by mutations in genes involved in the Notch signaling pathway, including DLL3, MESP2, LFNG, and HES7, which are critical for somitogenesis (33). The co-occurrence of spondylocostal dysostosis and split cord malformation supports the hypothesis that disruptions in somitic patterning and notochordal development can result in both vertebral and spinal cord anomalies.

Differential diagnosis

Confusing conditions

Split cord malformations are frequently associated with a spectrum of congenital anomalies, reflecting shared embryological origins. The unified theory of embryogenesis theorizes that split cord malformation arises from the formation of an accessory neurenteric canal during early gastrulation, which gives rise to an endomesenchymal tract that bisects the notochord and neural plate (38). This mechanism explains the frequent co‑occurrence of split cord malformation with vertebral segmentation defects (38). The presence of two or more midline lumbosacral cutaneous stigmata is particularly suggestive of an underlying lesion (28).

MRI is the key diagnostic tool for characterizing and differentiating split cord malformation from other vertebral segmentation defects. Split cord malformation is characterized by longitudinal division of the spinal cord into two hemicords, separated by a bony, cartilaginous, or fibrous septum. In split cord malformation type I, each hemicord is enclosed within its own dural sac; in type II, both lie within a single dural sac. MRI provides detailed visualization of the hemicords, septum, and surrounding structures (38; 43). The hemicords typically exhibit normal signal intensity, isointense to normal cord on both T1‑ and T2‑weighted images (38; 43).

Key distinguishing features of common mimics include the following (summarized in Table 1):

Spinal lipomas/lipomyelomeningocele. Often present with cutaneous stigmata and neurologic deficits; MRI shows a T1‑hyperintense mass (43; 23).

Myelomeningocele. At birth, presents as a non–skin‑covered mass with severe neurologic deficits; imaging shows herniation of neural elements through a vertebral defect (43).

Caudal regression syndrome. Absent or hypoplastic sacrum and lower vertebrae, blunt conus, often thickened filum terminale (43; 47).

Spinal dermal sinus/dermoid or epidermoid cysts. Cutaneous dimples, risk of infection; imaging shows sinus tract or cystic lesion (43; 23).

Tethered cord syndrome (other causes). Low‑lying conus with thickened or fatty filum (38; 22; 23).

Spinal segmental dysgenesis. Segmental absence or hypoplasia of cord and vertebrae (43; 47).

Neurenteric cysts. Ventral cystic lesions; may coexist with spinal cord malformation but are not diagnostic in isolation (38; 43; 47).

Vertebral segmentation anomalies. Hemivertebrae, butterfly vertebrae; may coexist with spinal cord malformation but do not cause cord splitting (47).

Syringomyelia/hydromyelia. Intramedullary cystic cavities within the cord.

Table 1. Summary of Common and Distinguishing Features for Differential Diagnosis of Split Cord Malformations

Condition	Common clinical features with split cord malformations	Radiographic distinguishing features
Spinal lipoma or lipomyelomeningocele	Cutaneous stigmata, neuro deficits	T1 hyperintense mass
Myelomeningocele	Open back mass, severe deficits at birth	Herniating neural elements, open defect
Caudal regression or sacral agenesis	Lower limb deformity, bladder/bowel issues	Absent sacrum, blunt conus, thick filum
Dermal sinus/cyst	Cutaneous dimple, infection, neuro deficits	Sinus tract/cyst
Tethered cord (other causes)	Progressive neuro deficits, pain	Low conus, thick filum
Spinal segmental dysgenesis	Severe lower limb deformity	Segmental cord/vertebral absence
Neurenteric cyst	Pain, neuro deficits, infection	Cystic lesion, ventral to cord; no split cord unless associated with spinal cord malformation
Vertebral segmentation anomaly	Spinal deformity, possible neuro deficits	Hemivertebrae, butterfly vertebrae, fusions; no split cord unless associated with spinal cord malformation
Syringomyelia or hydromyelia	Progressive neuro deficits, scoliosis	Intramedullary cystic cavity
(38; 38; 43; 22; 47; 23)

Associated or underlying disorders

Split cord malformations are most often sporadic, but several genetic syndromes and chromosomal abnormalities have been reported in association with split cord malformations. Notably, chromosomal defects involving 7q have been linked to simultaneous cranial and caudal midline anomalies, including split cord malformation, lumbosacral agenesis, and solitary median maxillary incisor (51), suggesting a single genetic defect can result in both cranial and caudal malformations. Jarcho-Levin syndrome, a genetic disorder characterized by vertebral segmentation defects and rib anomalies, may also include split cord malformation as part of its spectrum (11). Klippel-Feil syndrome (08), defined by congenital cervical vertebral fusion, is frequently associated with high cervical split cord malformation, likely due to disruptions in vertebral segmentation and possibly involving aberrant Pax-1 gene expression. These associations underscore the importance of considering genetic evaluation in patients with split cord malformation and multiple midline anomalies.

Visceral malformations, such as horseshoe or ectopic kidney, utero-ovarian malformations, and anorectal malformations, have also been observed in association with split cord malformation, further highlighting the broad spectrum of congenital anomalies that may co-occur due to early embryological disturbances (38; 10; 47).

Diagnostic workup

Historically, split cord malformation workup included amniotic fluid acetylcholinesterase, alpha-fetoprotein, urodynamic studies, and somatosensory evoked potentials; however, these are typically no longer used in resource-rich countries due to advancements in imaging (52; 20; 28). Diagnostic workup centers on proper radiologic imaging of the underlying abnormal anatomy. Particular attention needs to be paid to identifying potential secondary tethering lesions.

Prenatal work-up. The primary modalities for prenatal detection of split cord malformation are ultrasound and fetal MRI. Ultrasound serves as the initial screening tool but has limited sensitivity, particularly for fibrous septa or closed forms of split cord malformation. Characteristic sonographic findings include abnormal widening of the spinal canal, visualization of an echogenic septum, and bifurcation of the cord—best appreciated in coronal and axial planes. However, diagnostic performance is suboptimal: in a cohort of 120 cases, ultrasound detected spinal cord malformation with 51.7% accuracy, compared with 86.2% for fetal MRI, using postnatal imaging as the reference standard (50).

Fetal MRI is the preferred second‑line modality following antenatal ultrasound (05). Imaging is typically deferred until 17 to 18 weeks’ gestation to minimize risk to the developing fetus and to optimize spatial resolution (05). Recommended protocols include three‑plane scout, T2w TSE of the maternal pelvis, T2w SSFSE or HASTE, T2w EPI or trueFISP, T1w SPGR, and cine sequences (05).

The hallmark fetal MRI features of split cord malformation are direct visualization of two hemicords, identification of a midline septum (osseous, cartilaginous, or fibrous), and evaluation of dural sac configuration. T2w SSFSE sequences in axial and coronal planes provide high contrast between cerebrospinal fluid, neural tissue, and septal structures, enabling accurate localization and classification (35). T1‑weighted sequences facilitate detection of fat‑containing lesions, such as intraspinal lipomas, whereas bSSFP sequences further delineate cord and septal anatomy (35). As in postnatal imaging, the hemicords typically demonstrate normal signal intensity, isointense to unaffected cord on both T1‑ and T2‑weighted sequences (43).

Postnatal imaging work-up. MRI is the modality of choice for postnatal evaluation of split cord malformations, providing detailed characterization of the cord anatomy, the nature of the septum, dural sac configuration, and associated anomalies, such as tethered cord, lipomas, dermoid or epidermoid cysts, and syringomyelia. CT, particularly with high‑resolution bone algorithms, is superior for delineating osseous septa and vertebral anomalies—information that is especially valuable for surgical planning in split cord malformation type I (43). Recommended MRI protocols include three‑plane scout, T1w TSE, T2w TSE, T2w FS/Dixon/STIR, T1w TSE, T2w DRIVE/CISS/FIESTA, T1w TSE C+, T1w FS, T1w FS C+, DWI, and T2w GRE or ECHO-GRE (05).

CT is recommended in select situations, including detailed assessment of osseous septa in young children (< 3 years) where MRI bone signal is suboptimal, evaluation of complex vertebral segmentation anomalies, postoperative hardware assessment, or when MRI is contraindicated (05; 29). Ultrasound serves as a first‑line screening tool in neonates up to 3 months of age but lacks the resolution for definitive diagnosis or surgical planning (37).

Management

Indication for surgical management. In adults, the natural history of split cord malformation is generally benign, with slow progression of neurologic symptoms. The largest adult series to date, encompassing 94 patients with a mean follow-up of 64 months, demonstrated that most adults with split cord malformation remain stable for years without intervention (23). As the risk of progression in asymptomatic adults is low and the prognosis is favorable with observation, conservative management should include annual neurologic assessment and MRI for new or progressive symptoms (22; 23). Surgery in this population should be reserved for those with clear, progressive, or disabling symptoms, as improvement with conservative management is unlikely (0% for neurologic deficits and 12.5% for pain) (23). Conversely those who underwent surgery demonstrated an improvement rate of over 90% (22). The 10-year progression-free survival rate was 83.3% for those without associated hamartomas, dropping to 59.3% when a hamartoma was present (23).

In pediatric patients, the threshold for surgical intervention is lower due to a higher risk of neurologic deterioration, particularly in those with split cord malformation type I or associated tethered cord. However, select cases of split cord malformation type II without symptoms or with stable, nonprogressive findings (approximately 25%) may be managed conservatively with close monitoring, starting at neurologic assessment and MRI every 3 to 6 months initially (04; 06). However, many experts advocate for early surgical intervention of asymptomatic children to prevent irreversible deficits (36). In a pediatric series, 55% to 81% of children experienced improvement in neurologic function after surgery, and the risk of new, permanent neurologic deficits was very low (06; 02; 31; 36). However, there is no clear consensus on the timing of surgery.

Surgical management. The primary surgical goal is complete untethering of the spinal cord and removal of the septum (bony or fibrous) that divides the cord, while preserving neural elements and minimizing manipulation of the hemicords (38). The standard approach involves a posterior midline laminectomy or laminoplasty at the level of the split, with careful exposure of the dura and underlying structures (02; 30).

For split cord malformation type I, the procedure involves meticulous removal of the bony spur, which may be ventral or dorsal. The dura is opened longitudinally, and the septum is resected under direct visualization, with care to avoid injury to the hemicords and associated nerve roots. The two dural sacs are then reconstructed into a single sac to prevent retethering (30). In cases with associated lipomas or cysts, complete resection of cystic lesions is recommended, whereas lipomas may be resected, even subtotally, to avoid neural injury (02; 23). For split cord malformation type II, the approach is similar but generally less technically demanding, as the septum is softer and the risk of dural injury is lower. The septum is excised, and the cord is untethered, with attention to any associated anomalies (02; 23). Transection of the filum terminale is often performed in both types to ensure complete untethering, especially when a low-lying conus is present or when intraoperative findings suggest persistent tethering (06; 23).

Split cord malformations are frequently associated with other tethering lesions usually caudal to the split cord malformation, which need to be released to relieve the symptomatically stretched spinal cord. The associated lesions include thickened filums, dermoids or dermal sinus tracts, intradural lipomas, and neuroenteric cysts that can be other causes of tethered cord and, thus, also need to be surgically corrected. Myelomeningocele manque is an occult spinal cord lesion secondary to failed meningocele formation; it consists of taut fibrous bands admixed with dorsal paramedian nerve roots and blood vessels that tether the hemicords to where the fibroneurovascular stalk penetrates the dura. Myelomeningocele manque is commonly found and, because it contributes to cord tethering, necessitates repair. Hemicords sometimes occur in tandem in the same spinal cord (so-called composite split cord malformations). Also, hydrocephalus and syringohydromyelia can be associated, so care should be taken to image the entire neuraxis. These points are made to emphasize the importance of having a neurosurgeon with operative experience with split cord malformation involved in managing the case (01).

The optimal surgical strategy for patients with concomitant scoliosis and split cord malformation remains controversial. Some authors propose that split cord malformation may contribute to scoliosis progression and should be addressed prior to scoliosis correction (27). Others recommend that split cord malformation type I warrants surgical repair before scoliosis surgery, whereas type II may not require intervention (04; 42). Conversely, several studies have reported that patients with congenital scoliosis and split cord malformation can safely undergo spinal deformity correction without prior neurosurgical intervention or prophylactic detethering when neurologic status is intact or stable (12; 48). Furthermore, a 2019 series of 32 patients with congenital scoliosis and split cord malformation type I found that omitting bony spur resection prior to curve correction yielded satisfactory radiographic and clinical outcomes, with a potentially lower complication rate (53).

In high‑risk spinal surgeries, particularly in patients with multiple coexisting spinal pathologies, intraoperative neurophysiological monitoring (IONM) is recommended to reduce cord manipulation and prevent iatrogenic injury (19; 02). In one report of a pediatric female patient who underwent 12 operations for tethered cord, scoliosis, and split cord malformation, IONM detected a sudden, significant loss of transcranial electrical motor‑evoked potentials, prompting cancellation of the procedure. Without IONM, the patient might have sustained permanent paraplegia (19).

Perioperative and long-term management. Perioperative care follows standard neurosurgical protocols, including infection prophylaxis, pain control, and early mobilization. In pediatric patients, vigilant monitoring in the immediate postoperative period is critical for detecting new neurologic deficits, bladder or bowel dysfunction, and wound complications (30; 31). The most frequently reported are CSF leakage, transient urinary retention, and transient motor deficits; with modern microsurgical techniques, permanent morbidity is rare (02; 30). In adults, surgical morbidity rates are generally low but increase in revision cases or when complex associated anomalies are present (23). Neurogenic bladder requires aggressive management to prevent life‑threatening renal deterioration. Key measures include treatment of urinary tract infections, clean intermittent catheterization, and anticholinergic therapy; postoperative urodynamic studies are useful for establishing a new baseline (01). Optimal outcomes are achieved through coordinated follow‑up by a multidisciplinary team—typically including neurosurgery, orthopedics, urology, and rehabilitation medicine—both before and after surgical intervention.

Outcomes

Long-term outcomes after surgery for split cord malformation are generally favorable, as both pediatric and adult patients experience neurologic improvement or stability and a low incidence of significant permanent complications (28). In pediatric cohorts, improvement in neurologic function is seen in 55% to 81% of patients, with the remainder typically achieving stability; new permanent neurologic or urologic deficits are rare, and most complications are transient, such as cerebrospinal fluid leakage, transient urinary retention, or transient paresis (02; 36). In a study of 25 postoperative pediatric patients, quality of life was high, with a mean Health Utility Index-3 (HUI-3) score of 0.93 over a median 3.3-year follow-up, and 80% of children showed either stability (64%) or improvement (16%) in neurologic status (31).

In adults, surgery is associated with improvement in 61% of cases, particularly for radicular pain, and 10-year progression-free survival is 83.3% in the absence of associated hamartomas; the presence of hamartomas or the need for revision surgery increases the risk of late deterioration (23). Operative management in adults with preoperative neurologic deficits results in symptomatic improvement in 96.6% of cases, compared to 0% with conservative management (22). Permanent morbidity is rare when surgery is performed in specialized centers, and the overall prognosis is excellent with appropriate surgical management and long-term follow-up (02; 22; 36; 23).

The most common long-term sequelae are progression of preexisting spinal deformities, which may require subsequent orthopedic intervention, and rare cases of retethering or late neurologic decline (24). Late symptomatic recurrence (retethering) can occur in both age groups, sometimes more than a decade after initial surgery, but reoperation can provide substantial relief (24).

Patients with split cord malformations associated with meningomyelocele may have worse outcomes than those without meningomyelocele (25) although neurologic status may be stabilized following surgery for both conditions (17). One retrospective, longitudinal study of 65 patients showed that in a subgroup of patients who underwent tethered spinal cord surgery with the use of intraoperative neurophysiological monitoring at 12 years of age or younger exhibited a high rate of progressive scoliosis (09). It is unknown whether the progressive scoliosis is due to the tethered cord or other reasons; however, other studies have shown that patients with spinal dysraphism associated with tethering are predisposed to scoliosis (07).

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Contributors

All contributors' financial relationships have been reviewed and mitigated to ensure that this and every other article is free from commercial bias.

Authors

Marc Beaudin MD

Dr. Beaudin of Boston Medical Center has no relevant financial relationships to disclose.
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Alcy R Torres MD FAAP

Dr. Torres of Boston Medical Center and Boston University Chobanian and Avedisian School of Medicine has no relevant financial relationships to disclose.
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Editor

Alcy R Torres MD FAAP

Dr. Torres of Boston Medical Center and Boston University Chobanian and Avedisian School of Medicine has no relevant financial relationships to disclose.
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Former Authors

Stephen L Kinsman MD
Brittany Gerstein
Justine Ker BA
Stephen L Nelson Jr MD PhD
Michael V Johnston MD†

Patient Profile

Age range of presentation: 0 month - 65+ years
Sex preponderance: female>male

Split cord malformation

female:male 1.5:1
Heredity: heredity may be a factor
Population groups selectively affected: none selectively affected
Occupation groups selectively affected: none selectively affected

ICD & OMIM codes

ICD-10: Diastematomyelia: Q06.2

Congenital malformation of spinal cord, unspecified: Q06.9
ICD-11: Diastematomyelia: LA07.1

Other specified structural developmental anomalies of the neurenteric canal, spinal cord or vertebral column: LA07.Y
OMIM: Diastematomyelia: 222500

Spina bifida: #182940

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Split cord malformation

Associated Disorders

lumbosacral agenesis
solitary median maxillary incisor
Jarcho-Levin syndrome
Klippel-Feil syndrome
horseshoe or ectopic kidney
- utero-ovarian malformations
- anorectal malformations

Differential Diagnosis

spinal lipoma or lipomyelomeningocele
myelomeningocele
caudal regression or sacral agenesis
dermal sinus/cyst
tethered cord (other causes)
- spinal segmental dysgenesis
- neurenteric cyst
- vertebral segmentation anomaly
- syringomyelia or hydromyelia

Split cord malformation

Cite this article

Introduction

Overview

Key points

Historical note and terminology

Clinical manifestations

Presentation and course

Clinical vignette

Biological basis

Etiology and pathogenesis

Epidemiology

Prevention

Differential diagnosis

Confusing conditions

Table 1. Summary of Common and Distinguishing Features for Differential Diagnosis of Split Cord Malformations

Associated or underlying disorders

Diagnostic workup

Management

Outcomes

Special considerations

Pregnancy

Anesthesia

References

Contributors

Authors

Editor

Former Authors

Patient Profile

ICD & OMIM codes

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