Surgery a success for 23-day-old SMA type 2 girl with heart defects
Promising results seen in case of infant later treated with Spinraza
A 23-day-old girl with spinal muscular atrophy (SMA) type 2, later treated with Spinraza (nusinersen), underwent successful surgical repair of heart defects, according to a new case report.
The researchers noted that individuals with SMA may be perceived as risky surgical candidates, considering the poor prognosis for untreated patients.
But now the team, in Turkey, reported a “promising experience with a SMA type 2 patient undergoing a disease-modifying medical treatment.” Further, the researchers noted that SMA patients who receive such therapy “may be potential candidates for a successful surgical cardiac correction given their overall improved prognosis.”
The case was described in an article, “Surgical correction of a ventricular septal defect in a child with spinal muscular atrophy type 2 treated with nusinersen sodium: a case report,” published in the Journal of Cardiothoracic surgery.
Treating an infant diagnosed before birth
SMA is a neuromuscular disorder characterized by progressive muscle weakness and atrophy. Mutations in the SMN1 gene, which provides instructions for making the SMN or survival motor neuron protein, are the main cause of the disease. These mutations lead to the loss of motor neurons — the specialized nerve cells that control the muscles’ function.
The genetic disease is divided into five main types, from type 0 to type 5, according to the age at which symptoms first appear and whether or not patients reach certain motor development milestones.
Cardiac pathology or disease is more frequently reported among severely affected patients. Particularly at issue are structural and outflow tract defects.
Here, a team led by scientists at Koç University Hospital, in Istanbul, reported the case of a 3-week-old girl with type 2 SMA, diagnosed during pregnancy. Her case was associated with structural heart defects. One was patent ductus arteriosus, a persistent opening between the pulmonary artery, which is the main lung artery, and the aorta, the main body artery. This defect allows blood to skip circulation to the lungs. The other problem was ventricular and atrial septal defects, or a hole in the wall (septum) that divides the upper (atria) or the lower (ventricles) heart compartments.
The infant had a deletion in both copies of the SMN1 gene, and two copies of the SMN2 gene. She was referred to the neonatal intensive care unit with shortness of breath and poor feeding. Considering the potential post-operative morbidity, or the risk of post-operative complications in her case, and the uncertainty of access to disease-modifying treatments, a palliative procedure was decided.
At the age of 23 days, and weighing 3.7 kg (just over eight pounds), she underwent palliative pulmonary artery banding, to limit pulmonary blood flow, and patent ductus arteriosus ligation, to repair the hole in the artery.
Intubation was removed 16 hours after the operation, with clinicians noting the child had a stable pumping heart and good blood circulation. A postoperative evaluation by echocardiography, an ultrasound scan used to visualize the heart and close blood vessels, revealed no flow from the patent ductus arteriosus and normal pressure in the pulmonary band (55 mmHg).
The patient was discharged 10 days after surgery. During this period, she had no neurological symptoms, except for absent deep tendon reflexes.
At 1 year (12 months old), she scored a three on the Hammersmith Functional Motor Scale Expanded (HFMSE), a tool to assess the severity of motor disability in SMA, in which a lower score is indicative of worse function. At that point, the girl had not received the first dose of Spinraza, an approved SMA therapy. Spinraza was given at the age of 14 months.
Surgery successful in repairing heart defects
At 17 months, the child was admitted to the hospital for surgery to correct the atrial and ventricular septal defects and to reconstruct the pulmonary artery. At that time, no neurological deterioration was noted, and the patient was able to hold her head and sit unsupported. She weighed 8.2 kg, or about 18 pounds.
Postoperative echocardiography showed a residue on the ventricular septal defect, and a 14 mmHg gradient on the pulmonary artery. The patient was discharged nine days after surgery.
Before and after her fifth Spinraza treatment dose, 13 and 18 months after the second surgery, the patient’s Hammersmith scores were 25 and 41, respectively.
In the patient’s most recent follow-up, at age 4, her cardiac assessments were normal. In her physical and neurological examination, she had evident hypotonia or decreased muscle tone, but could walk unsupported, and reported improvement in motor skills with continuing treatment. Her Hammersmith score was 64.
In the literature, there are no reported cases of successful surgical repair of heart defects in SMA patients, the researchers noted.
However, “a surgical treatment approach may be possible as presented in this case,” the team wrote. From now on, they added, “we would prefer a single-step total cardiac surgical correction approach rather than a two-step correction with an initial palliation.”
According to the researchers, a clinical trial with Spinraza called NURTURE (NCT02386553) revealed that “infants and children who started treatment with [Spinraza] during the presymptomatic period attained motor milestones in timelines consistent with normal development.”
In the case reported, “despite the late treatment onset of our patient, the progress in her motor milestones is promising as documented by her Hammersmith scores,” the team wrote.