Spine Malformations

Open spinal dysraphism and primary neurulation disorder due to failure of closure of the neural tube and nondisjunction.

Neurological disabilities: paraplegia, incontinence, sexual dysfunction, skeletal deformities, pulmonary hypoplasia, breech position.

The presumed etiology is multifactorial. Folate administration during pregnancy reduces incidence.

Elevated amniotic fluid alpha-fetoprotein and acetylcholinesterase.

Fetal/intrauterine surgery may limit neural placode injury, preventing/limiting the intrauterine “dual hit” injury of the exposed neural placode. Compared to postnatal repair, in utero repair is associated with decreased CSF shunting, less hindbrain herniation, and improved lower extremity motor function.

Also known as myeloschisis

A myelocystocle is an open spinal dysraphism similar to myelomeningocele but differs from a myelomeningocele in that the exposed neural placode is flush with the skin and there is no herniating sac

Myeloceles account for ~30% of open spinal dysraphisms

Clinical implications of a myelocele as compared to a myelomeningocele have not been fully evaluated. One study has shown that myeloceles were more positively correlated with independent ambulation after prenatal repair compared to myelomeningocele.

Open neural tube defect with neural placode at the skin surface and no sac.

On fetal MRI, myeloceles are associated with higher Chiari 2 grade (i.e effaced 4th ventricle and cisterna magna) .

Skin covered closed spinal dysraphism and primary neurulation disorder caused by premature disjunction of neural ectoderm from the cutaneous ectoderm while the overlying ectoderm closes, allowing mesodermal precursors to gain access to the central core of the open/nonclosed neural tube, enhancing the development of a coexisting lipoma

The neural placode attaches outside the confines of the spinal canal onto fat which is in continuity with the enlarged subcutaneous fat.

Clinical: Patients present with tethered cord signs and symptoms. Bladder dysfunction usually occurs first around 2 years of age followed by motor and sensory dysfunction by the teenage years. Progressive neurologic dysfunction occurs without detethering and there is limited recovery if detethering is performed after symptom progression.

Herniation of spinal cord and meninges outside the spinal canal and attached to the lipoma that is in continuity with the prominent or mass-like subcutaneous fat

Associated with syrinx, diastematomyelia, spinal segmentation anomaly, caudal regression, and anorectal and genitourinary malformations

Closed spinal dysraphism with subcutaneous mass and primary neurulation disorder caused by premature disjunction of neural ectoderm from the cutaneous ectoderm

May present with lower extremity symptoms, back pain, and bowel/bladder dysfunction

Early surgical intervention recommended to reduce neurological impairment

The spinal cord-lipoma attachment is inside the spinal canal and in continuity with prominence/mass-like subcutaneous fat. The lack of herniation of the cord and meninges differentiates a lipomyelocele from a lipomyelomeningocele.

Associated with vertebral anomalies, terminal diastematomyelia, anorectal and genitourinary anomalies, epidermoid/dermoid, and dermal sinus tract

Closed spinal dysraphism with unknown embryological etiology

Herniation of fluid-filled meningocele sac through a defect in sacral or coccygeal vertebrae

Symptoms secondary to result of pressure on the bowel, bladder, or nerve roots

Fluid signal sac with communication to the spinal canal.

Associated with NF-1 and Marfan syndrome.

Closed spinal dysraphism .

A terminal myelocystocele consists of a skin-covered lumbosacral spinal dysraphism, an arachnoid-lined meningocele that is directly continuous with the spinal subarachnoid space, and a low-lying hydromyelic spinal cord that traverses the meningocele and then expands into a large terminal cyst which does not communicate with the subarachnoid space and is lined by ependyma and dysplastic glia. Terminal myelocystoceles are presumed to be a disorder of secondary neurulation caused by inability of CSF to exit the early neural tube causing the expansion and disrupting the overlying mesenchyme. Terminal myelocystoceles are associated with cloacal exstrophy, omphalocele, imperforate anus, ambiguous genitalia, caudal regression, and renal anomalies. Terminal myelocystoceles typically present with no bowel or bladder control and poor lower extremity function.

A nonterminal myelocystocele consists of a skin-covered spinal dysraphism, a CSF filled cyst, a meningocele and variable amount of dorsal fat continuous with the subcutaneous fat. Type 1 consists of the meningocele sac traversed by a fibroneurovascular stalk attached to the dome of the sac. Type 2 consists of focal hydromyelia that has displaced the posterior wall of the spinal cord into the meningocele sac. Nonterminal myelocystoceles are suspected to be disorders of primary neurulation with incomplete fusion of the dorsal neural folds/failure of the neural ectoderm to separate from the cutaneous ectoderm. Nonterminal myelocystoceles are associated with Chiari 2 malformations, hydrocephalus, ectopic cerebellar tissue, heterotopic renal tissue, and diastematomyelia. Nonterminal myelocystoceles often demonstrate no neurologic dysfunction at presentation.

Etiology unknown. Possibly secondary to teratogens based on animal studies with retinoic acid.

Early surgical repair maximizes neurological function

Divided into terminal and nonterminal myelocystoceles based on location.

Hindbrain herniation can be seen in ~40% of patients with myelocystoceles.

Skin covered spinal dysraphism/malformation with herniated spinal cord and meninges . The central canal is expanded and herniates into the meningocele.