Benign infantile spinal muscular atrophy

Skip constructs in spinal muscular atrophy: outcomes of a novel approach for posterior spinal instrumentation and fusion

PURPOSE

Many children with spinal muscular atrophy (SMA) develop progressive spinal deformity, worsening already compromised pulmonary function and global spinal balance. Early results demonstrate that intrathecal administration of nusinersen, a recent FDA-approved drug, improves motor function and ventilator-free survival, necessitating preservation of intrathecal access when considering PSIF. The purpose of this study is to assess medium-term outcomes of a specialized approach for posterior spinal instrumentation and fusion (PSIF) to preserve intrathecal access in patients with SMA.

METHODS

A retrospective review of patients with SMA undergoing PSIF at a single tertiary academic medical center during a 3-year period was completed. To facilitate intrathecal drug administration, the traditional approach to PSIF was modified to "skip" one or more intervertebral levels at the thoracolumbar junction. Clinical notes and radiographs were reviewed for postoperative outcomes including major coronal curve correction and complications, including loss of correction, hardware failure and surgical revision.

RESULTS

Eight patients were identified, with a mean age of 12.7 ± 1.6 years and follow-up of 4 years. These patients had a mean preoperative major coronal curve of 56.4°, with mean curve correction of 35.2°. At follow-up, no patients experienced rod breakage, loss of correction, or postoperative chronic pain. Only one patient required revision surgery due to bony overgrowth at the skipped level after three and a half years.

CONCLUSION

Implementing the skip construct approach for PSIF in patients with SMA allows for scoliosis correction without compromising intrathecal drug delivery. Follow-up at 4 years reveals no adverse clinical events, hardware failure or loss of correction.

LEVEL OF EVIDENCE

IV.

Spinal Muscular Atrophy Modeling and Treatment Advances by Induced Pluripotent Stem Cells Studies

Spinal Muscular Atrophy (SMA) is a neurodegenerative disease characterized by specific and predominantly lower motor neuron (MN) loss. SMA is the main reason for infant death, while about one in 40 children born is a healthy carrier. SMA is caused by decreased levels of production of a ubiquitously expressed gene: the survival motor neuron (SMN). All SMA patients present mutations of the telomeric SMN1 gene, but many copies of a centromeric, partially functional paralog gene, SMN2, can somewhat compensate for the SMN1 deficiency, scaling inversely with phenotypic harshness. Because the study of neural tissue in and from patients presents too many challenges and is very often not feasible; the use of animal models, such as the mouse, had a pivotal impact in our understanding of SMA pathology but could not portray totally satisfactorily the elaborate regulatory mechanisms that are present in higher animals, particularly in humans. And while recent therapeutic achievements have been substantial, especially for very young infants, some issues should be considered for the treatment of older patients. An alternative way to study SMA, and other neurological pathologies, is the use of induced pluripotent stem cells (iPSCs) derived from patients. In this work, we will present a wide analysis of the uses of iPSCs in SMA pathology, starting from basic science to their possible roles as therapeutic tools.

Curcumin and neurological diseases

Objectives: The beneficial effects of many substances have been discovered because of regular dietary consumption. This is also the case with curcumin, whose effects have been known for more than 4,000 years in Eastern countries such as China and India. A curcumin-rich diet has been known to counteract many human diseases, including cancer and diabetes, and has been shown to reduce inflammation. The effect of a curcumin treatment for neurological diseases, such as spinal muscular atrophy; Alzheimer's disease; Parkinson's disease; amyotrophic lateral sclerosis; multiple sclerosis; and others, has only recently been brought to the attention of researchers and the wider population.Methods: In this paper, we summarise the studies on this natural product, from its isolation two centuries ago to its characterisation a century later.Results: We describe its role in the treatment of neurological diseases, including its cellular and common molecular mechanisms, and we report on the clinical trials of curcumin with healthy people and patients.Discussion: Commenting on the different approaches adopted by the efforts made to increase its bioavailability.

Scoliosis and lung function in spinal muscular atrophy

The notes and radiographs of 43 patients with a confirmed diagnosis of spinal muscular atrophy were reviewed. A significant inverse linear relationship between the severity of scoliosis and the percentage of predicted vital capacity and peak flow was found. The patients who stood had a significantly better lung function than patients who were confined to a wheelchair, and their scoliosis deteriorated significantly more slowly. Sixteen patients underwent surgical spinal stabilisation, 4 with Harrington instrumentation and 12 with segmental spinal instrumentation, at an average age of 12 years and 11 months. The average curve correction achieved was 40%. The decline in lung function seen pre-operatively was not only reversed, but a significant improvement was found at final follow-up.

Prospective study of gross motor development in children with SMA type II

The natural history of SMA and the identification of predictive criteria of functional development are still a matter of discussion. This prospective study involved 20 children with SMA, aged between 3.10 and 15.7 years. The patients were followed from 1979 to 1992 in order to try to develop a greater understanding of the natural history of SMA at a very early age. A standardized protocol was used at regular intervals to assess parameters such as joint contractures, scoliosis and the milestones of gross motor functions. Our findings agree with the data in the literature concerning the early and generalized onset of joint contractures and scoliosis. A significant correlation was found between the level of acquired gross motor functions and walking with support. The acquisition of rolling by 5 years of age was the milestone that best correlated with the acquisition of walking with crutches and braces; furthermore the inability to roll seemed to correlate with the severity of the disease. These findings should be useful in planning a more rational rehabilitation program.

Prospective study of spinal muscular atrophy before age 6 years. DCN/SMA Group

Spinal muscular atrophy (SMA) is a common neuromuscular disorder of childhood, associated with a high mortality rate during the first 2 years of life. Most practitioners expect patients with SMA to follow a progressive course with loss of muscle strength and function over 2-10 years. Counselling sessions with parents frequently emphasize the high mortality rate and risk for respiratory failure. The progressive nature of SMA has been attributed to the loss of motor neurons. Fifty-eight children, ages 6 years and younger, were examined between January, 1987, and April, 1992, as part of a large, multicenter collaborative study of SMA. Muscle function was evaluated at regular intervals using a standardized protocol that was demonstrated to be reliable. We determined a prevalence of 56% for tongue fasciculations, a prevalence of 22% for facial weakness, and persistent deep tendon reflexes in one patient. Improved motor function and acquired milestones during the study were documented. This work should contribute toward a better understanding of the natural history of SMA.

Spinal muscular atrophy: the natural course of disease

The infantile form of spinal muscular atrophy (Werdnig-Hoffmann disease) is thought to be progressive and usually fatal by age three. The intermediate and juvenile forms (Kugelberg-Welander disease) have been reported to be static in many cases. A review of 48 patients, 50% of whom had been followed for more than 10 years, were placed into four groups according to the maximum motor function attained. Progression of muscle weakness was assessed using functional criteria, including inability to walk, inability to use a manual wheelchair and inability to raise the hands above the head. The results of this analysis suggest that all patients with spinal muscular atrophy have a progressive disease and that the course of the deterioration is predictable in each of the four groups. This information allows one to offer realistic counseling and a rational rehabilitation program.

[Tubular aggregates in a case of chronic proximal spinal atrophy]

The case of a 35 years-old man, with chronic proximal muscle atrophy in which at the muscle biopsy tubular aggregates were found by histochemistry procedures is reported. The tubular aggregates stained positive with the modified Gomori trichrome, haematoxylin-eosin, DPNH-diaphorase, non specific esterases, phosphorylase, P.A.S., oil red O and lactate dehydrogenase. They did not show in the routine and acid pre-incubated ATPase, acid and alkaline phosphatases and succinate dehydrogenase. Only found in type II fibers. A brief discussion about the pathogenesis and function of the tubular aggregates is made. The authors believe that the tubular aggregates in this case are secondary to prolonged use of phenobarbital and diphenylhydantoin, associated with the basic denervation process and alcohol abuse.

[Werdnig-Hoffmann disease: report of two cases?]

Two cases of familial spinal muscular atrophy with onset in infancy are reported. The author makes an attempt to categorize them and concludes by Werdnig-Hoffmann disease.