Q. What do you mean by spinal dysraphism?

Spinal dysraphism refers to a spectrum of congenital defects arising from abnormal closure, development, or separation of the neural tube and its surrounding mesenchymal structures. It includes open dysraphism (neural tissue exposed due to failed primary neurulation, e.g., myelomeningocele, myeloschisis) and closed dysraphism (skin-covered lesions resulting from disordered neurulation or mesenchymal differentiation, e.g., lipomyelomeningocele, dermal sinus tract, diastematomyelia).

 

Q. How do you classify spinal dysraphism?
 

Spinal dysraphism is broadly classified into:

Open spinal dysraphism (not covered with skin): These result from failed primary neurulation and include:

Myelomeningocele

Myeloschisis

 

Closed spinal dysraphism (skin-covered): These arise from defective disjunction or disordered mesenchymal development and include:

Lipomyelomeningocele

Lipomyelocele

Dermal sinus tract

Neurenteric cyst

Diastematomyelia (split cord malformation)

Fatty filum/Thick filum

Terminal myelocystocele

 

Complex dysraphic syndromes:

Currarino triad

OEIS complex

Caudal regression syndromes
 

Q. How does normal neurulation occur?

Neurulation proceeds in two phases:

Primary neurulation (third to fourth week): Neural plate folds and fuses to form the neural tube from cervical to upper sacral levels. This process requires coordinated bending, elevation, fusion, and separation of neural ectoderm from non-neural ectoderm.

 

Secondary neurulation (caudal cell mass): Mesenchymal cells condense, canalize, and fuse with the distal neural tube to form the conus and filum terminale.

 

Normal neurulation ends with dysjunction, the separation of neural ectoderm from surface ectoderm, allowing mesenchymal elements to migrate and form vertebral tissues.

 

Q. What are the embryological mechanisms leading to spinal dysraphism?
 

The embryological defects include:

Failure of neural tube closure causes open dysraphism such as myelomeningocele or myeloschisis.

Premature dysjunction causes mesenchymal invasion into neural folds and leads to lipomyelomeningocele.

Failure of dysjunction causes a persistent tract connecting skin and neural tube (dermal sinus).

Failure of secondary neurulation causes terminal myelocystocele, caudal regression, tight filum.

Midline mesenchymal cleavage anomalies cause diastematomyelia (split cord conditions).

Persistent neurenteric canal or endodermal misplacement causes neurenteric cysts.

Abnormal notochord formation or splitting causes associated vertebral segmentation defects.

The type of dysraphism depends on the timing and level of neurulation failure.

 

Q. What are the pathological differences between open and closed dysraphism?
 

In open dysraphism, neural tissue is externally exposed. The neural placode is continuous with skin edges and lacks meningeal or skin covering. These lesions inevitably involve Chiari II malformation, hydrocephalus, and brainstem abnormalities.
 

In closed dysraphism, the defect is covered by skin and neural elements are contained within the spinal canal. These lesions are more variable; some symptomatic at birth but others present later due to tethering, dermal sinus infection, or inclusion tumors.

 

Q. What is the epidemiology of spinal dysraphism?
 

The global incidence is approximately 1–3 per 1000 live births, with higher rates reported in regions with nutritional deficiencies, including parts of Asia. Myelomeningocele is the most common form. Females are more commonly affected in open dysraphism. 

 

Q. What are the major risk factors for spinal dysraphism?
 

Important risk factors include:

Maternal folic acid deficiency (most significant modifiable risk factor)

Maternal diabetes

Hyperthermia during early pregnancy

Teratogenic drugs (especially valproate and carbamazepine)

Genetic predisposition and consanguinity

Intrauterine infections and environmental toxins
Adequate folate supplementation reduces the risk by nearly 70%.
 

Q. How does spinal dysraphism present clinically?
 

Presentation depends on subtype.

Open dysraphism presents at birth with an exposed neural placode. Motor deficits, sensory loss, and bladder dysfunction are present from birth.

 

Closed dysraphism may be detected by cutaneous markers such as:

Hairy tuft

Dermal pit or sinus

Hemangioma

Subcutaneous lipoma

Skin tag

Asymmetric gluteal cleft

 

Neurological symptoms include:

Foot deformities

Progressive scoliosis

Back pain

Lower limb weakness

Sensory loss

 

Urological presentation includes neurogenic bladder, urgency, retention, and recurrent UTIs.

Dermal sinus tract may present with meningitis or dermoid abscess.

Split cord malformation may present with scoliosis, foot deformity, or tethered cord.

 

Q. Which associated anomalies are commonly seen with spinal dysraphism?

 

Chiari II malformation (universal in open dysraphism)

Hydrocephalus

Syringomyelia

Orthopedic deformities (clubfoot, hip dislocation)

Neurogenic bladder and bowel dysfunction

Vertebral anomalies (hemivertebra, butterfly vertebra)

Presacral masses in Currarino syndrome

 

Q. How do you investigate a child with suspected spinal dysraphism?

 

MRI spine is the investigation of choice; it identifies neural placode, fat infiltration, split cord anomalies, dermal sinus tracts, and tethering.

MRI brain to assess Chiari II and hydrocephalus in open dysraphism.

Ultrasound spine for neonates with skin markers (before ossification).

CT spine for bony anomalies such as diastematomyelia spur.

Urodynamic studies in all dysraphism patients at baseline.

Renal ultrasound for hydronephrosis due to neurogenic bladder.

 

Q. What are the general principles of managing spinal dysraphism?
 

Management is tailored to subtype but general rules include:

Open dysraphism requires urgent surgical closure within 24–48 hours to reduce infection risk and protect neural tissue.

Hydrocephalus evaluation and treatment (VP shunt or ETV) is integral.

 

Closed dysraphism is managed based on symptoms or high-risk features:

Progressive motor or bladder symptoms

Dermal sinus tract (absolute indication due to meningitis risk)

Lipomyelomeningocele with tethering

Split cord malformation with spur

 

Multidisciplinary approach with neurosurgery, urology, orthopedics, rehabilitation.

Long-term follow-up for re-tethering, scoliosis, and urological decline.

 

Q. What are the long-term complications of spinal dysraphism?

 

Progressive tethered cord due to growth

Re-tethering after surgery

Hydrocephalus requiring shunt revisions

Inclusion tumors (dermoid/epidermoid)

Orthopedic deformities

Chronic urological dysfunction leading to renal damage

Chronic pain and gait abnormalities

 

Q. What is the prognosis?
 

Prognosis depends on the subtype and timing of intervention.
Open dysraphism has lifelong neurological and urological morbidity, although early repair improves outcomes. Closed dysraphism has a more favorable prognosis if detected early and treated before neurological decline. Regular monitoring for re-tethering and bladder deterioration is essential.

 

Q. What is the Currarino triad?
 

Currarino triad is a congenital caudal dysraphism defined by the classic triad of anorectal malformation, hemisacrum (sacral defect), and a presacral mass such as an anterior meningocele, teratoma, or enteric cyst, resulting from abnormal development of the caudal eminence and notochord.

 

Q. What is the OEIS complex?

 

The OEIS complex is a severe midline developmental disorder characterized by Omphalocele, Exstrophy of the cloaca, Imperforate anus, and Spinal defects, representing one of the most severe forms of caudal dysraphism.

 

Q. What is caudal regression syndrome?

 

Caudal regression syndrome is a spectrum of secondary neurulation defects involving variable degrees of sacral agenesis, lumbar vertebral anomalies, and spinal cord dysgenesis, commonly associated with maternal diabetes and presenting with lower-limb, urological, and anorectal abnormalities.