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Spina Bifida

Definition

Neural tube defects can be grouped under the following terms
Spina bifida
Congential spinal disorder where the two halves of posterior arches fail to fuse leading to bony abnormality
Spinal dysraphism
Failure of the neural tube to close
Myelodysplasia
Any developmental defect of the spinal cord
Classification
1.Spina Bifida Cystica
Vertebral laminae absent with prolapse of neural elements/ meninges
Usually applies to meningomyelocoele
Meningocoele
Prolapse of the meninges only
No neurological deficit
Meningomyelocoele
Prolapse of the cord & the meninges in defect
Neurological deficit present
Myelocoele
AKA Myeloschisis, Rachischisis
Vertebral arches absent & neural tube is unfolded
Skin & sac absent – most severe form of defect
Neurological deficit present
Lipomeningocoele
AKA Leptomyelolipoma
Meningocoele that includes a lipoma involving the sacral nerve roots
2. Spina Bifida Occulta
Defect in vertebral arch
Contained meninges & cord
No relation to neural tube defects
“ Occulta “ = Secret
Seen in 5-10% of radiographs in normal population
May see telltale skin defects
Skin dimpling
Sacral pit
Hair tuft
Lipoma
May have diastomatomyelia
Fibrous, cartilaginous, or osseous bar creating longitudinal cleft in spinal cord
Can lead to tethering of the cord
Epidemiology
1-4/1000 live births
Varies with geographic location
Especially. seen in Celts
F > M
Increased to 1/20 with one affected sibling
Increased to 1/10 with second affected sibling
Aetiology
Multifactorial nature
Genetic & Environmental
Polygenic inheritance with teratogenic environmental factors
Decreased RBC folate associated with ↑ risk
Pathogenesis
Early problem 24-28th gestational day
Two theories
1. Failure of the neural tube to close
2. Initially closed tube that reopens due to ↑ intraluminal pressure
The latter theory is favoured & explains other defects such as diastomatomyelia etc
Prenatal Screening
Maternal Alphafetoprotein ↑
Identifies women at high risk
Will justify other investigations including
Amniocentesis
Detailed USS
Clinical features
Dependent on the neurosegmental level (see later)
CNS Problems
Spasticity
25% of lower limbs
Causes
Contracture & deformity
Difficulty with orthotic fittings
Impaired walking & sitting
Poor personal hygiene skills
More admissions & operations
Can be treated with
Intraspinal rhizotomy
Distal cordotomy
Deterioration
Due to other CNS abnormalities
May be sudden or insidious
Manifested by
Increased weakness
Increased spasticity
Increased pain
Discrepancy of > 2 levels between bony anomaly on XR & clinical level
Rapidly progressive scoliosis
Decrease of hand function or IQ
Vocal cord paralysis
Regular assessment required to detect these
Detailed neurological examination at each visit
CNS imaging indicated if deterioration
Head CT or MRI
Associted CNS Conditions
1. Hydrocephalus
90%
Causes
Poor IQ
Poor hand-eye coordination
Poor fine motor skills
Most need V-P shunt inserted at time of the defect closure
Shunt malfunction not uncommon
Manifested by
Vomiting/ Nystagmus/ Headache
Decreased conscious level
Decreased motor function
Increased paralysis
Increased scoliosis
2. Hydrosyringomyelia
50%
Related to hydrocephalus
4th ventricle communicates with the central canal of cord
Increased hydrocephalus pushes fluid into cord
Leads to
Increased lower limb paralysis & back pain
Weak upper limbs
Progressive scoliosis
Usually settles with the V-P shunt replacement for hydrocephalus
May need drainage prior to spinal procedure
Undrained syrinx may cause neurological deterioration
with curve correction
3. Arnold-Chiari Malformation
Type II (non-communicating) in 90%
Major features of type II are
Displacement of Cerebellar Tonsils into Cervical Canal
Distortion of Medulla Oblongata
Small shallow Posterior Fossa with enlarged Foramen Magnum
Symptoms are
Periodic apnoea
Stridor
Weak/ absent cry
Nystagmus
Upper limb spasm & weakness
May resolve with shunt
If not then surgically decompress
4. Tethered Cord
Almost universal to some degree
Attachment of cord to meningocoele sac prevents normal upward migration of the cord during growth
Even with release of cord from all attachments at time of closure there is high likelihood of reattachment during healing process
Only small number have symptoms
Buttock & posterior thigh pain
Increased spasticity & weakness in lower limbs
Progressive scoliosis
Treated with surgical release
Usually arrests progress
Not restore function
Neurosegmental Level
Named according to lowest functioning level
L4 is key level as quadriceps function » ambulation
Ambulation Categories (Hoffa)
Community Ambulator
Walk indoors & outdoors with or without orthoses
Wheelchairs only for long trips or to ↑ speed of ambulation
Household Ambulator
Walk only indoors with orthosis
Independent transfers or minimal assistance
Wheelchair for outdoor activities
Nonfunctional Ambulator
Walking only as therapy
Wheelchair to mobilise
Nonambulators
Wheelchair bound but often able to transfer from bed to chair
Classification of Neurological level
Modified Asher & Olsen
Tx no grade 3 strength in LL
L1,2 hip flexion or adduction
L3 knee extension
L4 knee flexion
L5 ankle DF
Symptoms ankle PF
Motor testing for neurologic level
Hip flexion L1, L2, L3 } essentially » flexion & adduction L2,3
extension L5, S1 } » extension & abduction L4,5
adduction L2, L3 }
abduction L4, L5, S1 }
Knee extension L3, L4
flexion L5, S1
Ankle DF L4, L5
PF S1, S2
inversion L4
eversion L5, S1
Toe DF L5, S1
PF S1, S2
Summary for neurosegmental level
Thoracic level
No voluntary function of lower limb
» Mobilise with wheelchair
High lumbar level (L1, L2, L3)
Hip flexors
± Hip adductors
± Knee extensors
» Child mobilises using HKAFO or KAFO
» 75% Adults (& adolescent) mobilise using wheelchair
Low lumbar level (L4, L5)
Above plus
Knee extensors & flexors
Ankle DF
± Hip abductors
» 75% Adults are community ambulators & majority use AFO
Sacral level (S1, S2, S3/4)
Above plus
Ankle PF
± Toe flexion
» 100% are community ambulators for limited distance (up to 90% of requirements)
± shoe orthosis
Specifics for neurosegmental level
Thoracic Level
» Non-walkers
Power
No voluntary muscle activity in lower limb
No fixed deformity
Position
Legs in position of gravity
ER at hips
Slight knee flexion
Equinus of ankle
Menelaus
? Higher rate of hip dislocation in this group than L2/ 3 levels
? Not related to muscle imbalance across hip
Ambulation
Child
Standing frame at 12-18/12 for 2-3 years
RGO in early years
Ie. Nonfunctional ambulators
Helps them to develop more normally & decreases contractures
Adults
Wheelchair as too much energy for mobilisation
Upper Lumbar L1-3
» Nonambulators 75%
» Household ambulators 25%
L1 Level
Power
Some hip flexion from Psoas (L1,2,3) =2/5
Position
Hip flexed, abducted & ER
Ambulation
Child
Possible to use RGO/ HKAFO
Adult
Usually wheelchair-bound
L2 Level
Power
Hip flexion from Psoas =3/5
Some adduction (L2,3) =3/5
Position
Hip flexed & adducted
FFD of hip may develop
Ambulation
Child
Most ambulate as children in HKAFO
FFD may need to be corrected first
Adult
Usually wheelchair-bound
L3 Level
Power
Hip flexion & adduction =4-5/5
Quads (L3,4) =3/5
Position
Hip flexed & adducted
Knee extended
Hip subluxation & dislocation
Common due to unopposed hip adduction & flexion
Ambulation
Usually household ambulators
If quads are 3/5 then
need KAFO to walk
88% in wheelchair
If quads are 4/5 then
98% household ambulators
82% community ambulators
Quads & no abductors » can ambulate with splint
Quads & good abductors » can ambulate without aids
Lower Lumbar L4-5
» Community ambulators 75%
L4 Level
Power
Quads =5/5
Hamstrings (L5, S1) =3/5
Tibialis Anterior (L4) =3-4/5
Tibialis Posterior (L4,5) =1/5
Position
Hip flexed & adducted
Knee extended
Ankle in varus
Foot variable*
Ambulation
Walk in AFO
Surgery often required to maintain
Hip extended
Knee extended
Foot plantigrade
L5 Level
Power
Hip abduction (L4-5, S1) =3-4/5
Tibialis anterior & posterior =3-4/5
Position
Calcaneus foot or Calcaneovalgus*
Ambulation
95% community ambulators throughout life
Foot surgery often required
*Low Lumbar with Spastic Sacral Segment
In addition to L4
Spastic hip abductors ?
Spastic hamstrings
Spastic calf
Spastic peronei
Deformity
Equinocavo-Valgus or Equinovalgus (peronei spastic)
Equinovarus (tib posterior spastic)
Calcaneus due to weak Achilles
Vertical Talus
Club Foot
Sacral Level
S1 Level
Power
Hip extension (gluteus maximus (L5,S1,2) =3/5
Gastrocnemius (S1) =3/5
Toe flexors (S1,2) =4-5/5
Position
Pes cavus
Clawing of toes from intrinsic minus position
Ambulation
Usually brace free but may need special shoes
S2 Level
Power
Normal
Position
May have claw toes
Ambulation
Normal
muscle charting should start immediately post-op
1/3 Complete LMN lesion & loss of sensation & bowel control below affected level
1/3 Complete lesion at some level but distal segment of cord preserved with mixed picture of intact DTR & spasticity
1/3 Incomplete & some movement & sensation preserved
Other deformities common such as
DDH
CTEV
Genu recurvatum
Claw toes
Initial Treatment
Selection of patients for closure of the defect is controversial
Two protocols
1. Some centres avoid urgent operation if
Level above L1
Severe deformity
Marked hydrocephalus
If not treated most die of meningoventriculitis
Survive if given antibiotics
More severely handicapped due to
Hydrocephalus
Continuing trauma to cord
2. Now almost all infants treated initially
» Ethically difficult to decide to not treat
Team orientated approach
Neurosurgery
Urology
Orthopaedics
Physio
OT
Initial treatment involves
Closure of defect within 24 hours
V-P shunt insertion
Orthopaedic Management
Menelaus Principles
1. Always manage in Spina Bifida clinic
2. Select surgery appropriate to future demands
3. Perform minimal surgery
4. Condense management
5. Correct muscle imbalance
6. Consider absent sensation, bone fragility, likelihood of infection
Principles
Promote walking if possible to
Promote normal bony development
Prevent contractures
Surgery is soft tissue
Release contractures
Tendon transfers
All surgery at one sitting
Simple surgery most appropriate in high level lesions
Wait until 12 months as
Spinal level & deformities evident & assessable
Most shunt & spine closure complications have been corrected
Goals
General
Ambulation requires
Range of motion
Absence of contracture
Stability
Motor power
Co-ordination
If surgery considered
More important to achieve ROM
Because stability can be provided by orthosis
Specific
Mobile & symmetrical hips
Ambulators ability to extend knees
Chair-bound ability to flex knees
Plantigrade foot
Straight spine
Indications for surgery
Posture stable
Pelvis level
Personal hygiene
Pressure sores
Preserve respiration
Hips Thoracic Level
Aim at achieving ROM
Functional range without contracture required to allow,
Sitting in wheelchair
Lying in bed
Orthoses for standing & walking
Surgery in form of contracture release
Reduction of hip not required
No sensation or muscle control in legs
Dislocation not common
If occurs, likely due to CNS problem
Dislocation usually doesn't reduce function
Even if unilateral
Reduction of dislocation difficult & often fails
Avoid Multiple Procedures
Leads to scarring
Causes loss of functional range
Orthotics required for lower limb stability
Must include hip, knee, ankle & foot (HKAFO)
Most give up walking by 8 years
Even if orthosis available
Parapodium, Swivel walker
Reciprocating Gait Orthosis may be better
Use wheelchair because
Uses less energy
Quicker
Hips Upper Lumbar
High incidence of hip dislocation
Unopposed hip flexion & adduction
Attempts to reduce hip often difficult
Due to uncorrected muscle imbalance
Best treatment is to release contractures causing FFD & adduction
Release of Iliopsoas & Adductors
Release Rectus Femoris if tight
Then treat as a thoracic level
Better to have flaccid flexible hip than a strong stiff hip
Hips Middle / Lower Lumbar
Hip usually undergoes progressive dysplasia & dislocation
Due to hip flexion & adduction during stance phase for stability
Progressive acetabular dysplasia
Dislocate age 3-4
Unilateral disease in child with good quads & potential walker should be reduced
Traditional treatment was muscle release
But may lead to weakness & ↑ instability
Requires orthosis to stabilize hip for walking
Another option is tendon transfer
Iliopsoas to Greater Trochanter (Sharrad transfer)
Decreased hip dysplasia
Problems with stair climbing
Weakness of hip flexion means Rectus must be used to flex hip
Causes knee extension & difficulty climbing stairs
Can be remedied with physiotherapy
Hip reduction must be performed first
At age 1 year
Open reduction
Varus shortening femoral osteotomy performed for femoral neck deformity
Pelvic osteotomy performed for acetabular dysplasia
Reduction of Hip (Menelaus)
No Quads & bilateral » Never } above L4
No Quads & unilateral » Sometimes }
Quads & Bilateral » Sometimes } L4 & below
Quads & Unilateral » Always }
Knees
Aim for straight knee that is braceable
Straight knee is stable position
Quadriceps weakness
Treatment with KAFO
Extension contracture
May interfere with walking
Most can be treated with serial casts & splints
If resistant, VY-plasty of quadriceps tendon
Flexion contracture
Not important in chair-bound
Treatment in ambulators by
Release Hamstring & Gastrocnemius
± Posterior capsulotomy
If near skeletal maturity with large FFD could consider distal femoral extension osteotomy
Ankles & Feet
Rigid & flail deformities in anaesthetic feet
Majority have Deformity
50% have Equinovarus deformity
20% have Calcaneus deformity
20% have Normal feet
10% have Valgus, Equinovalgus, Cavus & Claw Toe deformities
Aim For Braceable Plantigrade Feet
Almost all will require brace
Equinovarus
Most common deformity
Due to lesion at L3 or L4
Spintage & casting initially
Well padded serial casting as insensate skin
Stretching often corrects varus
May require percutaneous lengthening of TA
Attempt casting until age 6 months
If fails, operate at age 12 months
Usually PMR
If fails, may require talectomy
If fails, triple arthrodesis after skeletal maturity
Calcaneus
L5 level most common
Due to unopposed
Tibialis anterior
Toe extensors or peronei
And weak
Gastrocnemius
Os calcis becomes vertical
Leads to heel ulceration
Treatment with release of offending tendons
Leave treatment until 3 years to fully assess problem
? Dynamic EMG to assess tendon transfer
Tibialis anterior to calcaneus
Valgus
Usually less problem than varus
Caused by
Lateral tilt of ankle mortise
Valgus subtalar joint
Can be managed often with AFO
Can be treated by
Supramalleolar osteotomy
Grice subtalar arthrodesis
Transfer tends to fail
Cavus
Sacral level
Weak Tendo Achilles
± Claw toes
Due to lack of intrinsic power S2
Corrected by
Jones Tendon Suspension
Tendon transfer EHL to metatarsal heads & IPJ fusion
Steindler stripping
Tarsal/ Metatarsal osteotomy
Spine
Scoliosis
Most common skeletal deformity (80%)
More common with high lesion
Aetiology
May be due to 3 factors
Congenital
Due to congenital malformations
Neuromuscular
Combination of
Paralysis
Instability with no posterior elements
Neurological
Progressive neurological abnormality
Hydrosyringomyelia
Failed VP shunt
Tethered cord
Curve similar to idiopathic curve
Management
Orthotics
Temporary measure
To delay fusion
In order to allow development of trunk height
Problems with pressure sores
Surgery
Need good dorsal soft tissue
Indications for intervention
Failure of orthotic management to maintain curve < 45°
Scoliosis in 12 yo previously controlled with brace
Progressive spinal decompensation
Progressive pelvic obliquity
In the form of
Anterior release & fusion + Posterior segmental fusion
Avoids Crankshaft effect
If > 12 yo consider posterior only
Kyphosis
Difficult problem
Trouble sitting
Ulcerations over kyphus
Can't see ahead
Breathing difficulties
May be treated with
Excision of Kyphotic segment
Excision of distal cord
Lordosis
Usually corrected by correction of FFD of hip
Difficulties with spinal surgery
Deficient posterior elements
Previous sac repair
Anterior fusion forms the basis
Blood loss higher
Infection rates higher
Foot & Ankle 2
Lateral tilt of ankle in mortise
May require supramalleolar osteotomy with medial closing wedge if severe enough
If sufficient growth remaining then consider medial epiphysiodesis of the distal tibial physis (< 6 years of age)
Subtalar
Peroneal tendon releases
If fails then consider Grice ST fusion & calcaneal osteotomy
If close to maturity then look at Triple Arthrodesis
Cavus
Pressure effects major problem
Up to 5 years consider Plantar release
If fails then look at Metatarsal osteotomies
If associated varus of heel then add calcaneal osteotomy
If close to maturity & significant deformity then look at Triple Athrodesis
Claw toes treated with Jones procedure & Hibbs to lesser toes & PIPJ fusion
Extensor tenotomies & dorsal capsulotomies of MTPJ
CVT
< 2% of childen with SB
Similar reduction as per other forms of CVT
Should attempt in first year of life
External Rotation of Tibia
Commonly associated with valgus ankle
Requires supramalleolar osteotomy > 8 yo if severe
Fractures
Most often around knee
Most common at age 3-7 years
Often painless
Only diagnosed with
Redness
Warmth
Swelling
Usually heal with abundant callus/ heterotopic ossification
Usually treat nonoperatively
Avoid disuse if possible
Urinary Complications
Major cause morbid/ mortality
Spastic paralysis of bladder
Leads to
Urinary incontinence
Hydronephrosis
Recurrent UTIs
Renal failure
Addressed by
Intermittent catheterization
Bladder augmentation
Latex Allergy
Latex is organic substance obtained from rubber tree
Ubiquitous in hospitals, households, community
Sensitisation occurs during surgical procedures
Incidence of latex reactions related to number of previous operations
Can develop
Contact dermatitis type IV hypersensitivity)
Urticaria, rhinoconjunctivitis, asthma, anaphylaxis (type I hypersensitivity)
Fatalities reported in the US