Neuromuscular Scoliosis

Epidemiology

 

Prevalence of 25-100%

 

Ambulation

- walking decreases incidence

 

Age 

- worse with young onset

 

Aetiology

 

Exact biomechanical explanation of origin & progression of curves unclear

 

Associated with

- weakness 

- poor muscle control

- no proprioception

 

Classification

 

1. Neuropathic

 

A. UMN

- CP 

- Friedrich's

- cord tumour / trauma

- CMT

 

B. LMN

- Polio

- Spinal muscle atrophy

- Spina Bifida

 

2. Myopathic

- Arthrogryposis

- Muscular Dystrophy

- Myotonia Dystrophica

 

NHx compared with Idiopathic 

 

Onset younger

More rapid progression

Progression after skeletal maturity / throughout life

Longer curve

Cervical involvement

Pelvic obliquity

Pulmonary complications common

 

Curve

 

Long C shaped curve

- compensatory curve uncommon but possible

 

Curve associated with

- pelvic obliquity

- hip contractures / dislocation

- cervical involvement

 

Other problems

 

Lung disease common (decreased FVC, LRTI) 

Poor nutrition 

Pressure areas

CRF in Spina bifida

 

Management

 

Aims

 

Maintain cardiorespiratory function

Promote mobility & ambulation

Preserve sitting balance

Improve cosmesis

 

Principles

 

Brace till 12 years then fuse

 

Earlier if

- lose control with rapid progression

- large curve

 

Nonoperative

 

Indications

 

Small curves < 30°

Large curves in patients with very poor prognosis

 

Orthoses

 

Best overall initial treatment

- rate of progression slowed

- allows further spinal growth before definitive treatment

 

TLSO

- 2 piece custom moulded

- used to control & correct scoliosis or kyphosis in growing years

- preferable to Milwaukee brace in NM conditions

- easier to make and wear with reduced incidence of press sores

- worn during day while child is upright

- off at night

 

Seating

- very important

- aims to give trunk & spine control

- able to correct postural curves

- no effect on structural curves

- significantly decreases nursing & handling time

 

1. Tumbleform Seat

- moulded seat for infants

- 3 sizes

 

2. Commercial Chairs

- pelvic support, abduction pillow, thoracic support, head support

 

3. Moulded Sitting Support Orthosis

- AKA SSO

- custom fitted support made from patient mould

- provides maximum sitting support with padded supports & belts

 

Surgery

 

Neuromuscular Scoliosis Posterior Fusion

 

Aim

 

Solid arthrodesis of balanced spine over level pelvis

 

Requirements

 

Long, solid fusion from upper thoracic to lower lumbar

Rigid instrumentation & massive bone grafting

 

Issues

 

Increased bleeding

Osteopenic bone / Poor hold

Fusion to pelvis

High pseudarthrosis rate

Poor medical state

 

Ambulation

- fusion may eliminate ability to ambulate

- trunk movement may be important for ambulation

- obviously lose any spinal movement with flexion

- should test in brace first

- may need to limit extent of surgery

 

Preoperative

 

General medical workup

- cardiopulmonary status

- especially Friedreich's & Duchenne MD

- FVC1, FEV, ABG's

 

Book ICU bed

 

Approach

 

Posterior

- most common especially in CP

- moderate curve

 

Staged Anterior / Posterior

- severe kyphosis / severe rigid scoliosis (> 45°)

- posterior fixation compromised (SB)

- < 9 years to stop crankshaft deformity

 

Technique

 

Require

- spinal cord monitoring if indicated

- cell saver

- post op ICU bed or HDU

- IDC

 

Instrumented fusion

- proximally from T3 or T4 to prevent later subsequent deformities

- caudally to pelvis if >15° pelvic obliquity

- to L4 or L5 if balanced

- often need sublaminar wires for large C shaped curve

- place in midcurve to pull spine to the rods

- large fusions require allograft

 

Blood Loss

- issue because extensive approach / small  blood volume / osteopenic bone bleeds+++

- addressed with meticulous haemostasis / hypotensive anesthesia / haemodilution / cell saver

 

Complications

 

Pulmonary complications

- most common cause of death

- nearly all CP patients get pneumonia post op 

 

Neurological injury

- especially if correcting curve > 90°

- spinal monitoring

- if damaged when wake up, remove metalwork

 

SIADH

- careful fluid balance 

 

Infection

- bacteraemia from remote sites especially  UTI

- increased incidence of wound infection

 

Loss of ability to ambulate

- due to loss of trunk flexion and extension

 

Cerebral Palsy

 

Most common neuromuscular cause of scoliosis in western world

 

Principles

 

Professor Bruce McPhee, Royal Brisbane Hospital

- key is that they all continue to progress past maturity

- says as general rule all need operation so can pick your timing

- try not to fuse too early as get very short trunk

- no longer goes to pelvis 

- feels that stopping at L5 is adequate and pelvis is not worth the morbidity

- insists CP patients have their operation at 50o

- if families decline he won't operative at 70-80o because then they need 2 stage

- high associated morbidity

- follow up every 6 or 12 months

 

Incidence

 

10% in ambulatory patients

70% spastic quadraplegics

 

Lonstein Classification

 

Group 1 curves (A&B) have level pelvis

- double thoracic curve

- little pelvic obliquity

- fuse as for idiopathic

 

Group 2 curves (C&D) have pelvic obliquity

- large lumbar or thoracolumbar curve

- marked pelvic obliquity

- fuse long (T4) to pelvis

 

Algorithm

 

Observation

- curves up to 30˚ in the growing child

- curves up to 50˚ in skeletally mature

 

Orthoses

- often only postpones arthrodesis until puberty

- seating most common form of non-operative treatment instituted

- TLSO effective in ambulatory patient

 

Surgery

 

Fusion to sacrum essential with pelvic obliquity

- Galveston technique (iliac wing rod fixation)

- pedicle screws only viable in S1, not S2

 

Spina bifida

 

Incidence

 

>60% of patients with myelomeningocoele develop scoliosis

 

Principles

 

The higher the level the more severe

- T12 - 100%

- L1 - 90%

- L2 - 80%

- L3 - 70%

- L4 - 60%

- L5 - 25%

- S1 - 10% 

 

40% incidence of spinal dysraphism

- may cause scoliosis progression

- hydrocephalus, syringomyelia, tethered cord, Arnold Chiari

 

20% have congenital component

 

Most require surgery

 

Why fuse wheelchair bound Spina Bifida children?

 

Physiological

RFT's

Feeding

- often use peg

- tends to disappear into skin folds

- hygiene & technical difficulties

Acid reflux when hunched over

Only tolerate small feeds

 

Physical

Pressure areas

Ability to nurse

Takes arm off chair so can do ADL's

Allows stable sitting

Pelvic obliquity

Allows coverage of hips

 

Psychosocial

Self-esteem both patient & carer

Allows better interaction with environment

 

Poor prognostic signs

 

Early age of onset

Asymmetrical motor paralysis

Presence of spasticity

10% - 20% have congenital scoliosis

 

Algorithm

 

Curve 20-40˚

- TLSO

- but bracing complicated by pressure sores

 

Curve > 40˚

- anterior and posterior fusion

- need anterior as posterior elements deficient

- pelvis may be deficient

- attempt to preserve lumbosacral segments to aid wheelchair transfers

 

Duchenne's muscular dystrophy

 

Incidence

 

Usually lose ability to walk during age 9-12 years

- due to progressive weakness

- 80 - 100% develop severe collapsing scoliosis

 

May progress rapidly (2-3˚/ month)

- can progress to 100o

- 10o per year once in chair

 

Issues

 

Affects ability to sit

 

Scoliosis is life threatening

- progressive respiratory compromise

- due to respiratory muscle weakness and curve

- with curve > 35˚, vital capacity 40% of predicted

- further compromises respiratory problems

- death occurs in late teens to early twenties

- may be delayed by curve correction

 

Bracing

 

Orthotic use little success

- almost all progress

- slows progression (15˚ / year comparted with 30˚ / year)

 

Surgery Indications

 

Curve greater than 30o

FVC < 30% predicted

Life expectancy > 2 years

 

Surgery

 

Only posterior

- anterior compromises respiratory function too much

 

Spinal muscular atrophy

 

Most patients develop scolioses

- onset by age 7

- usually progressive

- consider surgical treatment when curve reaches 40o

- large C shaped curves

- T2 to sacrum

 

Friedreich's ataxia

 

All have scoliosis

- 50% have hyperkyphosis

- curve patterns resemble idiopathic rather than neuromuscular

- curves appear later

- late teens or early 20's

- consider surgical treatment when curve reaches 40o

 

Paraplegia and quadriplegia

 

Incidence

 

Age related with risk of spinal deformity

- 90% if cord injury preadolescent

- due to loss of sensory / proprioceptive / motor functions supporting the spinal column

 

Posttraumatic angular deformities related to crush fractures