Definition
- Scoliosis due to neuromuscular cause
Aetiology
Etiology | Prevalence (%) |
Cerebral palsy | 25 |
Myelodysplasia | 60 |
Spinal amyotrophy | 67 |
Friedreich's ataxia | 80 |
Duchenne myopathy | 90 |
Medullary lesion (< 10 years of age) | 100 |
- The prevalence of scoliosis varies (25–100%) depending on the condition (e.g., 25% in cerebral palsy, 90% in Duchenne muscular dystrophy).
- The Scoliosis Research Society (SRS) classifies them as
- Neuropathic OR
- CNS involvement
- PNS involvement OR
- Both
- Myopathic
Types | Conditions |
Central neurological causes | Cerebral palsy, hereditary ataxia, syringomyelia, encephalopathies, Rett’s syndrome. |
Peripheral neurological causes | Poliomyelitis, spinal muscular atrophy, hereditary neuropathies, familial dysautonomia. |
Mixed central and peripheral neurological causes | Medullary lesions, myelodysplasia, myelomeningocele. |
Neuromuscular junction (motor end-plate) | Myasthenia |
Muscular causes | Duchenne muscular dystrophy, Becker muscular dystrophy, limb-girdle dystrophies, Steinert myotonia, arthrogryposis. |
Pathogenesis
- Spinal deformity is due to a mixture of,
- Trunk muscle weakness
- Asymetrical muscle tone:
- Hypertonia
- In CNS aetiology: it may be induced by disharmonious control of trunk musculature around the spinal axis, progressively worsening due to a lack of effective muscular compensation.
- Lead to progressive imbalance, worsening as compensatory mechanisms fail.
- Sequalae of spinal deformity:
- A long thoracolumbar curve extending to the pelvis, inducing pelvic obliquity, is a classic form of neuromuscular spinal deformity.
- Pelvic obliquity can arise from: Use Stagnara test to assess
- "Upper origin": (A)
- Asymmetric retraction of muscles connecting the trunk and pelvis.
- "Lower origin": (B)
- Hip posture asymmetry causing retraction (usually adduction, flexion, internal rotation), → pelvic malpositioning → accentuates the underlying scoliosis.
- This highlights the importance of optimal symmetrical hip posture, especially in non-walking patients.
- Kyphotic deformity with trunk collapse
Clinical Assessment
Clinical Assessment
- Muscle Tone/Joint Stiffness:
- Assessing for both hyper- and hypotonia in different joints
- Spinal Deformity Evaluation: Static and dynamic assessments in sitting, standing, prone, and lateral flexion positions to determine curve reducibility.
- Prone examination
- With the patient lying at the end of the table with lower limbs in flexion.
- This displays residual curvature after eliminating abnormality due to limb-length discrepancy, pelvic asymmetry and gravitational effects.
- Curvature reducibility can be judged again in lateral inclination, as can the flexibility of the ilio-lumbar angles.
- Pelvic obliquity
- Performed with the patient sitting at the edge of a table (with assistance if needed) to better assess trunk deformity and its sagittal and frontal components.
- Asymmetric hip stiffness
- can be a primary symptom, leading to imbalance in a seated posture and creating areas of hyperpressure on the ischia.
- It also underlies pelvic obliquity of lower origin, which aggravates spinal deformity.
- Hip range of motion and Contractures
- Prone examination:
- Patient lying at the end of the table with lower limbs in flexion, to display residual curvature after eliminating effects of limb-length discrepancy, pelvic asymmetry, and gravity.
- Hip range of motion evaluation should take account of pelvic positioning, which needs to be spatially correct before taking angle measurements.
- Stagnara Test
- to assess if the hips are the driver of pelvic obliquity or it is originated at the spine
- Dynamic trunk examination:
- Assesses deformity reducibility by studying the spine level by level in lateral inclination and rotational movement.
- Reversibility can also be judged by passively trying to raise the patient by the head by the examiner
Static examination:
- Gait Analysis:
- Differentiating between
- Full ambulators
- Partial ambulators
- Non-ambulators
- If surgery endangers walking autonomy, it might be wise to postpone it.
- Associated Complications:
- Pressure sores, respiratory dysfunction, nutritional deficiencies, and urinary/digestive dysfunction.
Respiratory Assessment and Management
- Essential examination due to three reasons:
- Spinal deformity's impact on ventilation mechanics
- Underlying neurologic pathology impairing ventilation
- Treatment (conservative/surgical) having immediate respiratory impact.
- Can be affected by
- Swallowing disorder
- Poorly controlled epileptic state
- Fragile nutritional status
- Regular respiratory rehabilitation can be combined with instrumental techniques:
- Intermittent positive pressure breathing devices
- e.g., Alpha 200
- Maintain rib-cage flexibility and improve thoracic ampliation, for stiff spinal deformity with thoracic hypokyphosis or severe chest deformity.
- "Cough-assist" devices
- Useful for elevated risk of tracheobronchial congestion, especially in hypotonic or bed-ridden/fatigued patients (e.g., postoperatively).
- Non-invasive ventilation
- via oral or nasal mask improves spontaneous ventilation
- may be used before heavy surgery and during the first postoperative months in fragile patients.
- Invasive ventilation via tracheotomy
- may be required for severe respiratory insufficiency or swallowing disorder with recurrent congestion
- Should be discussed multidisciplinary preoperatively to avoid emergency tracheotomy.
Cardiac Assessment
- Minimal cardiac assessment is mandatory before arthrodesis in neuromuscular spinal deformity.
- Duchenne muscular dystrophy
- Myocardial contractility is impaired
- potentially with sudden onset around 10-11 years, necessitating rapid surgical stabilisation.
- Steinert myotonic dystrophy
- involves conduction disorder, screenable by Holter or preoperative intracavitary recording;
- a preoperative electrosystolic training probe may be needed to prevent peroperative arrhythmia.
Usual name | Genetic abnormality | Location | Type of cardiac involvement |
Duchenne muscular dystrophy | DMD gene | Xp2.1 | Cardiac insufficiency |
Becker muscular dystrophy | DMD gene | XP2.1 | Cardiac insufficiency |
Emery-Dreifuss muscular dystrophy | EMD and LMNA genes | Chromosome X, Chromosome 1 | Conduction disorder, arrhythmia |
Limb-girdle or Erb muscular dystrophy | Polygenic, recessive or dominant | Linked to X | Cardiac insufficiency |
Steinert myotonia | DMPK gene | Chromosome 9 | Conduction disorder |
Rett's syndrome | MECP2 gene | Chromosome X | Cardiac dysautonomia, rhythm disorder |
Trophic Assessment
- Nutritional deficiency
- should be suspected in cases of weight loss or stagnation during growth
- Needs to be addressed in months preceding surgery.
- Nocturnal feeding (nasogastric tube or gastrostomy) may be considered weeks/months before arthrodesis in difficult cases.
Urinary Disorder
- Preoperative management for chronic urinary infection is mandatory, including urine sterilisation and rigorous catheterisation protocols.
- Spinal deformity changes may affect self-catheterisation technique.
Imaging
- Seated and Supine Radiographs:
- To assess deformity severity and flexibility.
- For non-walking hypotonic patients,
- Specific Views:
- "Bending" and traction views to evaluate flexibility of curves and pelvic obliquity.
- AP views under asymmetric traction can assess frontal reducibility of pelvic obliquity.
- MRI:
- Indicated for underlying spinal cord pathology.
- to detect associated syringomyelic cavities that may cause per- or postoperative neurologic aggravation.
- CT Scan:
- Especially for thoracic deformities and airway concerns.
- Thoracic CT is recommended for spinal deformity with thoracic hypokyphosis or lordosis, as bronchial caliber anterior to spinal convexity is often reduced;
- severe "bronchial stretching" can cause atelectasis and reduced lung volume.
Management
Prevention and Conservative Care
- Prevention of Spinal Deformity:
- Preventing retraction and pathologic posture of the trunk and limbs
- Countering asymmetric hip posture is the most effective way to prevent pelvic obliquity and "lower origin" scoliosis.
- Preventing hip flexion contracture stops lumbar/lumbar-sacral hyperlordosis.
- Hamstring retraction causes knee flexion contracture, hindrance to upright stance, and progressive retroversion of the pelvis and lumbar kyphosis.
- Traction
- Bracing
- Orthopedic treatment should be very early in pathologies causing severe muscular deficiency (quadriplegia, type 1 and 2 spinal amyotrophy).
- Begins with passive bracing, correcting the spine by traction with a "Barchois-type" corset (pelvis to skull).
- More conventional Chenau corsets or folded corsets for nocturnal hypercorrection may be used for milder deficiencies (e.g., cerebral palsy, cerebellar ataxia, neuropathy, muscular pathology).
- Some neurologic disorders (e.g., dystonia) are not amenable to corset treatment.
- Often an interim measure awaiting vertebral arthrodesis, but effective in limiting consequences like impaired pulmonary development and function, making future surgery simpler.
Surgical Management
- Indications:
- Progressive, severe, or functionally debilitating deformities.
- Relatively early surgery may be justified for strongly evolutive and difficult-to-contain deformities, but conservative treatment should continue if chest development and respiratory capacity can still be gained by trunk growth.
- Timing:
- A compromise: not too late (for less severe/more reducible deformity) and not too early (to limit thoracic hypertrophy and restricted lung volume).
- The clinical and radiological criteria of spinal maturity are a matter of debate in neuromuscular disease
- Triradiate cartilage closure is a good sign of axial skeletal maturity, but may be late in case of resistant hip dislocation secondary to the neuromuscular pathology.
- Multidisciplinary Approach:
- Involvement of orthopedists, anesthesiologists, pulmonologists, cardiologists, nutritionists, and rehabilitation specialists is critical.
- Objectives:
- Two objectives:
- Correction of spinal deformity
- Correction of pelvic obliquity.
- Achieve a well-aligned spine and pelvis, correct pelvic obliquity, restore sitting/balance, and prevent further progression.
- Achieve frontal alignment of pelvic and scapular belts.
- Techniques:
- For severe pelvic obliquity, patient positioning in asymmetric traction on a Cotrel table is effective.
- Segmental techniques using pedicle screws or specific iliac extension screws provide good anchorage and fixation flexibility.
- Combining several pelvic anchorages (sacral and iliac) with rod segments helps "share" mechanical risk during correction.
- Segmental pedicular screwing, especially in the apical region, provides 3D spine control, preventing evolutive deformity (crankshaft phenomenon) when the spine still has growth potential. This avoids preliminary epiphysiodesis.
- Correction by in-situ progressive contouring of rods is effective, distributing stress.
- Progressive spinal distraction rods can be useful for poorly controlled deformities, but have complication risks at fixation sites.
- Multiple anchorage with implants at each vertebral arthrodesis level is a good solution for poor bone quality in osteoporotic patients.
- Sublaminar implants (e.g., Universal Clamp) can be used in the deformity concavity to limit screw detachment.
- Preliminary release of deformity convexity is only justified in rare cases where residual pelvic obliquity exceeds 10° on preoperative traction views.
- Pelvic obliquity correction requires extending the spinal assembly down to the pelvis.
- The pelvic-spinal assembly should allow isolated sequential correction of pelvic positioning relative to the spinal assembly.
- Iliosacral screwing is limited by specific connectors and poor sacrum bone quality. Traditional pelvic extension techniques (e.g., Galvestone) may also fail due to poor anchorage.
- Postoperative Care:
- Usually begins with a few days/weeks of intensive care, a critical period for respiratory and infectious complications.
- A bivalve protection corset may aid early verticalisation without stress.
- Several weeks in a rehabilitation center are usually required before discharge home.
- Rehabilitation:
- Early mobilization using protective bracing, often followed by weeks in a rehab facility.
- Outcome
- Studies show objective postoperative functional improvement and quality-of-life benefits.
Complications
- Morbidity is considerable and far greater than in idiopathic deformity.
- SRS database confirms high prevalence (>17%) of general and infectious complications, with non-negligible mortality risk.
- Severe respiratory or hemodynamic complications leading to death were reported in 0.3% of cases, concerning fragile patients
- Respiratory:
- Major risk factor; managed with breathing support (noninvasive or tracheotomy if needed).
- Prevention
- Good preoperative respiratory assessment and management, often with non-invasive ventilation or tracheotomy.
- Neurologic:
- Prevention
- Intraoperative monitoring is standard, especially in peripheral neuromuscular conditions.
- which is feasible for peripheral neurologic/muscular pathology but more difficult for central pathologies.
- Infectious:
- Vigilant preoperative preparation and postoperative wound care essential;
- factors like malnutrition or poor hygiene should be corrected.
- Prevention more difficult
- Known risk factors include
- Cutaneous colonisation
- Chronic urinary/pulmonary infection
- Malnutrition
- Poor oral-dental/cutaneous status
- Surgery time
- Peroperative bleeding.
- Early surgical revision and prolonged antibiotherapy are often favourable.
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