Neuromuscular scoliosis is a coronal and sagittal plane deformity of the spine in patients with abnormalities of the nervous system or muscles i.e. myoneural pathways of the body.
The progression more severe in case of neuromuscular scoliosis and continues into adulthood. The long-term effects of the spinal deformity in patients with neuromuscular conditions can be disabling.
Ability to sit and pulmonary function can be markedly affected.
The prevalence of spinal deformity in patients with a neuromuscular disorder ranges from 20% in children with cerebral palsy to 60% in patients with myelodysplasia.
In Duchenne muscular dystrophy, it can rise to 90%.
The severity of scoliosis increases with the severity of the neuromuscular disease.
Pathophysiology
The exact pathophysiology is not very well understood. Though muscle weakness is one of the factors but there seems more because there is no consistent pattern of scoliosis is associated with a particular pattern of weakness.
Classification by Scoliosis Research Society
Neuropathic
Upper-motor-neuron lesions
- Cerebral palsy
- Syringomyelia
- Spinal cord trauma
Lower Motor Neuron Disease
- Poliomyelitis
- Spinal muscular atrophy
Myopathic
- Arthrogryposis
- Muscular dystrophy
- Myopathy
Clinical Presentation and Diagnosis
The deformity is often seen in childhood. The age of the presentation would vary with the condition and severity of the condition. For example, cases with severe cerebral palsy can often be seen in the first year of life.
A patient with neuromuscular scoliosis requires a thorough assessment of the whole body.
It is essential to establish the diagnosis of the underlying disease. In cases of muscle dystrophies, a muscle biopsy may be done.
Spinal deformity, decompensation, and shoulder balance are documented. The deformity is measured by plumbline and shoulder balance by spirit level.
Detailed examination of all the all extremities and joints for contractures is done.
Ambulatory, nutritional and functional status of the patient is also evaluated.
Depending on ambulation status, patients may be labeled as walkers, sitters, or non-sitters.
Lab tests are done as part of patient preparation and include CBC, proteins levels to know nutritional status and biochemistry profile.
X-rays are required to evaluate the spinal curve. AP and lateral spine views are obtained in standing or sitting or supine position depending on the ability of the patient to stand or sit.
FOr knowing Traction spinal radiographs are obtained to evaluate the flexibility of the curves. These can be obtained in the radiology department with manual distraction with a head halter and leg traction.
Wherever Patients capable of cooperating should be evaluated preoperatively with pulmonary function studies
Treatment of Neuromuscular Scoliosis
The goals of treatment are
- To maintain the spine in a balanced position in the coronal and sagittal planes
- A level pelvis.
Nonoperative treatment is by a custom molded thoracolumbosacral orthosis and molded seating supports. Nonoperative treatment aims to control the curve during spinal growth rather than correcting the deformity.
This delays the need for surgical treatment in the early years. With pubertal growth, the surgery may become necessary as the control of the curve is lost.
Curve progression and worsening of sitting ability are the main indications for surgery.
Patient’s ability to undergo surgery should be confirmed especially the nutritional adequacy and cardiorespiratoy function.
Spinal fusion is done to arrest the growth progress. As compared to idiopathic scoliosis, fusion is necessary at a younger age, and the fused portion of the spine is longer.
Fusion to the sacrum is done in cases where children do not have sitting balance or have pelvic obliquity.
Fusion can be posterior or combined anterior-posterior.
The combined procedure is commonly done in cases
- where posterior elements are absent [myelodysplasia]
- To gain correction in a rigid lumbar or thoracolumbar curve
- To balance over a level pelvis
The instrumentation used are
- Multiple hook-rod systems, with or without the addition of sublaminar wires
- Luque rod and sublaminar wires
- Iliac screws for sacral fusion
The combination of somatosensory and motor evoked potentials are done during surgery
Intraoperative use of halo-femoral traction aids in the correction of pelvic obliquity.
In the postoperative period, after the acute phase is over, patients are mobilized as early as possible.
References
- Myung KS, Lee C, Skaggs DL. Early pelvic fixation failure in neuromuscular scoliosis. J Pediatr Orthop. 2015 Apr-May. 35 (3):258-65.
- Bridwell KH, O’Brien MF, Lenke LG, Baldus C, Blanke K. Posterior spinal fusion supplemented with only allograft bone in paralytic scoliosis. Does it work?. Spine (Phila Pa 1976). 1994 Dec 1. 19 (23):2658-66.
- Sarwahi V, Sarwark JF, Schafer MF, Backer C, Lee M, King EC, et al. Standards in anterior spine surgery in pediatric patients with neuromuscular scoliosis. J Pediatr Orthop. 2001 Nov-Dec. 21 (6):756-60.
- Shao ZX, Fang X, Lv QB, Hu ZC, Shao SY, Hu YB, et al. Comparison of combined anterior-posterior approach versus posterior-only approach in neuromuscular scoliosis: a systematic review and meta-analysis. Eur Spine J. 2018 Sep. 27 (9):2213-2222.
- Funk S, Lovejoy S, Mencio G, Martus J. Rigid Instrumentation for Neuromuscular Scoliosis Improves Deformity Correction Without Increasing Complications. Spine (Phila Pa 1976). 2016 Jan. 41 (1):46-52. .
- Toll BJ, Samdani AF, Janjua MB, Gandhi S, Pahys JM, Hwang SW. Perioperative complications and risk factors in neuromuscular scoliosis surgery. J Neurosurg Pediatr. 2018 Aug. 22 (2):207-213.
