SPINA BIFIDADefect in the vertebral arch of the spinal cord – incompletely formed or absent.Deformity occurs during development in utero

Epidemiology Incidence 1-2 per 1000, Highest rate in British isles (Ireland , Whales).

Africans and African Americans have lowest rates Familial tendency Female predominance (60% children affected are female)

EtiologyMultifactorial inheritanceEnvironmental factors – nutrition and folic acid; Teratogens–Drugs especially Carbamezapine and Valproic acid (anticonvulsants)

Pathogenesis>Embryology Trilaminar germ disk – 3rd week Ectoderm cells overlying the notocord thicken to form the neural plate. Lateral edges of neural plate elevate – neural folds with neural groove at the

center Neural crest cells migrate into mesenchyme and will form dorsal roots Neural folds approach and fusei from the cervical area caudally and cranially

forming neural tube Anterior and posterior neuropores close at day 25 and 27 respectively Spinal cord develops from neural tube 4th week, mesoderm proliferates at midline forming paraaxial mesoderm. This is

arranged longitudinally forming somites. Each somite forms sclerotome around spinal cord which will differentiate to form the vertebrae

MalformationsFailure of fusion of dorsal vertebrae or failure of neural groove to close

Classification 1. Spina bifida cystica

Menigocele – herniation of meninges Meningomyelocele – spinal cord and nerve roots herniated. 94% Lipomeningocele – lipomatous mass herniates and attaches to spinal cord

tethering it Myelocelemyelocele, or myeloschisis- open neural plate covered by

epithelium and the neural plate has spread out onto the surface.2. Spina bifida occulta - Lesion covered by skin, no herniation. Skin stigmata i.e. hairy patch, dimple, dermal sinus tract, lipoma, haemangioma etc seen. Lesion usually above the gluteal fold along the spinal cord

Most common sites are the lumbar and sacral regions

Associated anomaliesMeningomyeloce show increased incidence of Chiari II malformation, Hydrocephalus Syringomyelia, Brainstem malformations, Cerebral ventricle abnormalities (cranial nerve) Midline abnormalities – VACTREL

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Pathophysiology

Problem caused when spinal cord contents herniated or the neural tube is completely open and the ependymal layer is exposed (myelocele or myeloschisis)

Lack of protection of nervous tissue causes damage mechanically or from lack of vascular support, desiccation, or from other insults. This results in features like neurogenic bowel and bladder, a contracted bladder leads to hydronephrosis along with infections and renal failure,

Asymmetric innervation causes muscular imbalance, which leads to joint contractures and developmental deformities such as hip dislocation and spinal deformities.

Seizure activity secondary to the neural tube defect may be noted.

Chiari II malformations can cause deterioration of neurologic system with time and may present with signs of brainstem compression (stridor, central apnea, dysphagia, quadriparesis, nystagmus, myelopathy

EVALUATION

Aim to evaluate function and associated anomalies

Initial examination

>Local

Assess skin for skin stigmata If swelling, check for translucency, fluid thrill felt at the fontanelles. In

meningomyelocele, sac appears velvety red or yellow with thin fragile vessels imbedded in the arachnoid may be able to se spinal cord and nerves as dark shadow when checking translucency. Meningocele usually covered partly or wholly by skin.

>General

1. Site and level of lesion2. Motor and sensory levels

Type 1 – segmental level with flacid paralysis, loss of sensation and loss of reflexes. Type 2 – Interruption of long tracts only either partially or complete

3. Associated hydrocephalus4. Associated orthopaedic deformity (hip dislocation, CTEV, vagus and varus

deformities, scoliosis etc)

5. Other associated deformities –vertebral, cardiac, anorectal, esophageal, renal. Give attention also to the anus to assess function of the sacral root

Investigation

Imaging Studies:

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Plain radiographs – orthopaedic deformities Ultrasound scan - to rule out hydrocephalus, tethering of spinal cord and

urogenital tracts, kidneys

CT scan

o To evaluate hydrocephalus and any obstructive lesions, Anatomical detail is generally good,

MRI

o Superior anatomical detail and assists the surgeon in choosing the best treatment. Necessary in endoscopic treatment,

o The lateral ventricles have a characteristic appearance in almost all patients with spina bifida the occipital horns are more dilated than the frontal horns, and the long axis of the lateral ventricles tend to be parallel.

Supportive investigations

Full haemogram, urea and electrolytes, urine cultures and urinalysis, skin sensitivity tests, CSF studies

TREATMENT

Multidisciplinary involving neurology, neurosurgery, paediatrics, physiotherapy, orthopedics,

>Immediate treatment

Cover open NTD with saline moist sponge to avoid rupture or drying Give systemic antibiotics if leaking

Constitute a management team

>Definitive

Spina bifida cystica: Repair can be done immediately

Step 1: Circumnavigate the neural placode without injuring any of the neural elements. Once completed, neural placode is placed into the spinal canal. Many methods available

Step 2: Identification and dissection of the dura then covering the neural placode covered using the dura. If the dura is absent, the muscle fascia is used.

Step 3: Skin closure in layers,

Shunt placement during myelomeningocele closure

Approximately 20% of all patients with myelomeningoceles have significant hydrocephalus at birth; another 60-70% of patients develop it after the myelomeningocele is closed. In select patients, placement of a shunt during the same operation for closure of a myelomeningocele is entirely reasonable.

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Outcome and prognosis

Reduced intellect with hydrocephalus, CNS infections and degree of neurological impairment

Continence – 10-15% of meningomyelocele have continence. Clean intermittent cathetirisation have better outcome

Ambulation – depends on level of lesion and other muskuloskeletal affection>Hip flexors and quadriceps most important for ambulation. >Sacral lesions have better outcome.>Ability to ambulate reduces with ageClassified into

Community ambulators – move indoors, outdoor with crutches with or without braces

Household ambulators – only indoors with crutches, with or without brace

Functional –On wheelchairs and learning to use crutches with or without braces

Non functional – wheelchair bound Independence – 60% will attend normal classes, 40% special classes. 10-40%

of meningomyelocele patients are employable

Prevention

Primary – folic acid preconception

Secondary – Screening -Alpha fetoprotein in maternal blood or amniotic fluid at bwn 15 – 20 weeks; Ultrasound

i Surgery Grand roundSpina bifidaPresentor: Gregory Ganda

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