Spinal muscular atrophy and pregnancy

Management of Spinal Muscular Atrophy in the Adult Population

Spinal muscular atrophy (SMA) is a group of neurodegenerative disorders resulting from the loss of spinal motor neurons. 95% of patients share a pathogenic mechanism of loss of survival motor neuron (SMN) 1 protein expression due to homozygous deletions or other mutations of the SMN1 gene, with the different phenotypes influenced by variable copy numbers of the SMN2 gene. Advances in supportive care, disease modifying treatment and novel gene therapies have led to an increase in the prevalence of SMA, with a third of SMA patients now represented by adults. Despite the growing number of adult patients, consensus on the management of SMA has focused primarily on the pediatric population. As the disease burden is vastly different in adult SMA, an approach to treatment must be tailored to their unique needs. This review will focus on the management of the adult SMA patient as they age and will discuss proper transition of care from a pediatric to adult center, including the need for continued monitoring for osteoporosis, scoliosis, malnutrition, and declining mobility and functioning. As in the pediatric population, multidisciplinary care remains the best approach to the management of adult SMA. Novel and emerging therapies such as nusinersen and risdiplam provide hope for these patients, though these medications are of uncertain efficacy in this population and require additional study.

Pregnancy and delivery in women with spinal muscular atrophy

OBJECTIVES

To expand the limited available knowledge about pregnancy and delivery in women with spinal muscular atrophy (SMA) using a cohort of genetically proven SMA patients from USA.

METHODS

This was a cross-sectional questionnaire-based study. We mailed questionnaires to 58 women with confirmed SMA.

RESULTS

Thirty-two women responded, reporting 35 pregnancies, including 19 women with at least one pregnancy. In this cohort, preterm labor and delivery by cesarean section were more common in mothers with SMA particularly SMA type 2. Seventy-four percent of mothers reported increased weakness during pregnancy that persisted after delivery in 42%. SMA mothers generally had a positive experience and good outcomes and elected to have more than one pregnancy.

CONCLUSION

This information regarding pregnancy in women with genetically confirmed 5q SMA will prove useful in guiding future research and in providing counseling to women with SMA.

Histologic and transcriptional assessment of a mild SMA model

Spinal muscular atrophy (SMA) is caused by survival of motor neuron (SMN) deficiency, leading to specific motor neuron attrition. The time course and molecular pathophysiologic etiology of motor neuron loss observed in SMA remains obscure. Mice heterozygous for Smn show up to 50% motor neuron attrition by 6 months of age and are used as a model for mild SMA in humans. To determine both the rate of cellular loss and the molecular events underlying motor neuron degeneration in SMA, motor neuron counts and mRNA quantification were performed in spinal cords of Smn(+/-) mice and wild-type littermates. Surprisingly, despite the chronic, subclinical nature of motor neuron loss, we find that the bulk of the loss occurs by 5 weeks of age. RNA isolated from the spinal cords of 5 week-old Smn(+/-) mice subjected to microarray analysis reveal alterations in genes involved in RNA metabolism, apoptosis and transcriptional regulation including a general perturbation of transcripts coding for calcium binding proteins. A subset of these changes in expression was further characterized by semi-quantitative RT-PCR and Western blot analysis at various time points. Taken together, these results indicate that spinal cord cells present the first signs of the apoptotic process consistent with a response to the stress of Smn depletion. A picture of comparatively rapid neuronal attrition in spite of the very mild nature of SMA is obtained. Furthermore, changes occur, which may be reactive to and not causative of the cellular loss, involving central cellular functions as well as calcium modulating proteins.

Anesthetic management of spinal muscle atrophy type II in a parturient

We report the peripartum management of a 30-year-old wheelchair-bound nullipara woman with spinal muscular atrophy (SMA) type II, including severe restrictive lung disease and Harrington rods. At 38 weeks gestation, she was admitted for an induction of labor with neuraxial analgesia, but she subsequently had to be delivered via cesarean section under general anesthesia. We describe the anesthetic implications of SMA on labor and delivery management and review the available literature.

Clinical commentary: obstetric and respiratory management of pregnancy with severe spinal muscular atrophy

We present a combined obstetric and respiratory perspective on two pregnancies for a woman with severe Type 2 Spinal Muscular Atrophy (SMA). Our patient had the lowest prepregnancy weight (20 kg) and vital capacity of 0.34 L (VC 11% predicted) yet to be reported in the sparse literature on pregnancy with SMA. She delivered two live healthy infants via planned caesarean section without pregnancy or neonatal complication. We describe the respiratory and obstetric management techniques used for a pregnancy with this degree of respiratory compromise.

Anaesthesia for caesarean section in spinal muscular atrophy type III

We describe the conduct of general anaesthesia for a patient with spinal muscular atrophy Type III (Kugelberg-Welander disease) undergoing elective caesarean section. Apart from a delayed return of skeletal muscle power following non-depolarising neuromuscular blockade the procedure was uneventful. We found no previously published reports of general anaesthesia for caesarean section in this condition in the English language literature. We review the available literature and discuss the potential anaesthetic problems in the management of obstetric patients with this degenerative neuromuscular disorder.

Successful pregnancies for ventilator users

This case series describes full-term pregnancies despite no autonomous ability to breathe due to poliomyelitis or ventilatory insufficiency due to severe kyphoscoliosis. Three women with postpoliomyelitis who were continuously dependent on noninvasive intermittent positive pressure ventilation and one woman who developed ventilatory insufficiency due to severe kyphoscoliosis became pregnant and delivered healthy, full-term babies. They had vital capacities of 240, 250, 280 (5% of normal), and 880 ml (14% of normal), respectively, when becoming pregnant. The up to continuous use of noninvasive intermittent positive pressure ventilation can permit the natural completion of pregnancies of women with little or no ability to breathe unaided.

Successful pregnancy in a patient with spinal muscular atrophy and severe kyphoscoliosis

Pregnancy imposes a load on the respiratory system that is usually easily assumed because of alterations in the thoracoabdominal architecture. It is presumed that the respiratory mechanical disadvantage of severe kyphoscoliosis and the muscle weakness of spinal muscular atrophy impede these adaptations sufficiently to preclude a successful gestation. We report the case of a successful pregnancy in a woman with spinal muscular atrophy, severe uncorrected scoliosis, and the lowest spirometric values reported in the literature without the use of ventilatory support. This patient demonstrates that women with severe kyphoscoliosis and a profound ventilatory limitation can carry a successful pregnancy well into the third trimester without requiring full ventilatory support.

Anaesthesia for caesarean section in a patient with spinal muscular atrophy

This report describes a 33-year-old primigravid woman with spinal muscular atrophy Type III (Kugelberg-Welander syndrome). Elective caesarean section was performed at 38 weeks gestation under spinal anaesthesia. The implications of spinal muscular atrophy for anaesthesia for caesarean section are described.

Caesarean section conducted under subarachnoid block in two sisters with spinal muscular atrophy

Spinal muscular atrophy is a rare chronic neurological condition characterised by degeneration of the anterior horn cell. Experience with the anaesthetic management of the pregnant patient with this condition is limited. We report the clinical details of two wheelchair-bound sisters, who underwent elective caesarean section within a few weeks of one another. Both patients were safely managed with subarachnoid anaesthesia without any deterioration of their underlying neurological condition. It is hoped that this report will add to the evidence that subarachnoid anaesthesia can safely be used for caesarean section in chronic neurological conditions and, in particular, spinal muscular atrophy.