Spinal Muscular Atrophy (SMA)


Spinal muscular atrophy (SMA) affects many organs and systems in the body, including the musculoskeletal and respiratory systems. Patients may need different types of surgery to manage the symptoms of the disease and improve their quality of life.

Scoliosis Surgery

Scoliosis is one of the main comorbidities of SMA, affecting almost all patients with SMA types 1 and 2 and about 50% of those with SMA type 3.1 It is caused by the weakness of the muscles that normally support the spine. When the spine is not supported properly, it bends sideways, causing pain, breathing difficulties, and reduced mobility.

sma scoliosis
X-ray of Thoracic-Lumbar spine in dark background. Thoraco-Lumbar scoliosis.

Several factors affect the timing and type of scoliosis surgery. These include the age of the patient, the severity and location of the curve, and the patient’s breathing function.2 Generally, surgery is performed when a patient is aged 10 years or older and has stopped growing. Surgery is recommended in patients who have scoliosis that is contributing to breathing problems.

There are 3 main types of surgery that can be performed to treat scoliosis. These include spinal fusion, growing rods, and vertical expandable prosthetic titanium ribs (VEPTR).2

Spinal Fusion Surgery for SMA

In spinal fusion, 2 or more vertebrae are permanently connected using a bone or bone-like material in the space between the vertebrae. Rods, hooks, screws, or wires can be used to hold the vertebrae together until the bone grafts fuse and heal. This type of surgery eliminates motion between the vertebrae and prevents further growth of the spine. It is usually only performed after the patient has stopped growing.

spinal fusion hardware sma
X-ray of spinal fusion hardware.

Growing Rods for SMA

Growing rods are attached to the top and bottom of the spine with screws or hooks. Since the growing rods are expandable, they can be readjusted as the spine grows. However, this requires repeat surgeries every 6 months to 1 year. There are also magnetically controlled growing rods that can be adjusted as the patient grows without the need for further surgery.

VEPTRs for SMA

Vertical expandable prosthetic titanium ribs (VEPTRs) are similar to growing rods. They can be attached to the ribs or spine to help straighten the spine and separate the ribs. This can help prevent the deterioration of breathing. Like growing rods, VEPTRs need to be adjusted every 6 months as the patient grows.

Hip Surgery

In some patients with SMA, the pelvis and hips may be affected, causing pelvic obliquity.2 Pelvic obliquity can cause hip dislocations and, in severe cases, patients may need hip surgery.

Some researchers think hip surgery can improve balance, maintain pelvic alignment, and reduce pain.3 Others, however, have questioned the benefits of a surgical approach as partial dislocations, or subluxation, often recur following surgery.

Tracheotomy

Most patients with SMA type 2 or 3 usually only need noninvasive ventilation, where breathing support is delivered through a mask placed over the nose or nose and mouth. For some patients with SMA type 1, noninvasive ventilation may not be sufficient and these individuals may require a tracheostomy tube.4 A tracheotomy is therefore required.

sma Tracheotomy
Tracheostomy cannula with white obturator and deflated cuff.

Gastrostomy and Fundoplication

For patients who have serious difficulties chewing and swallowing due to muscle weakness, gastrostomy may be an option.6 

This is the insertion of a feeding tube into the stomach through the abdomen so that food can be directly delivered to the stomach without having to go through the mouth, throat, and esophagus (ie, a G-tube). It involves a surgeon making a small skin incision on the left side of the abdomen, insertion of the gastrostomy tube, and the closure of the stomach around the tube.7  

For those with gastroesophageal reflux disease (GERD), fundoplication may be performed to attach the stomach to the lower esophageal sphincter and help reduce acid reflux.8

Muscle Biopsy

Muscle biopsy is a minor surgical procedure that can be used to diagnose SMA,9 wherein a small sample of muscle is surgically removed from the patient and examined for any signs of the disease. There are 2 main types of muscle biopsy: a needle biopsy, where a needle is inserted into the muscle to collect a small piece of tissue as it is removed, and an open biopsy, where a small incision is made into the skin and the muscle to remove a sample of muscle tissue.10

Surgical Considerations

All types of anesthesia have been used in patients with SMA and none are contraindicated.8 

Surgical complications are often related to respiratory failure and infections, and they are more common in patients with SMA type 1 or 2.8

Reviewed by Michael Sapko, MD on 7/1/2021

References

  1. Scoliosis in spinal muscular atrophy. Spinal Muscular Atrophy UK. Accessed June 10, 2021.
  2. Scoliosis in SMA. SMA Foundation. Accessed June 10, 2021.
  3. Zenios M, Sampath J, Cole C, Khan T, Galasko CSB. Operative treatment for hip subluxation in spinal muscular atrophy. J Bone Joint Surg Br. 2005;87(11):1541-4. doi:10.1302/0301-620X.87B11.16216
  4. Breathing risks and care. Cure SMA. Accessed June 10, 2021.
  5. Tracheostomy. Mayo Clinic. October 22, 2019. Accessed June 10, 2021.
  6. Tube feeding and SMA: recommendations and practices. Cure SMA. Accessed June 10, 2021.
  7. Feeding tube insertion – gastrostomy. Mount Sinai. Accessed June 10, 2021.
  8. Anaesthesia recommendations for patients suffering from spinal muscular atrophy. Orphan Anesthesia. Accessed June 10, 2021.
  9. Spinal muscular atrophy (SMA). UCSF Benioff Children’s Hospitals. Accessed June 10, 2021.
  10. Muscle biopsy. UCSF Benioff Children’s Hospitals. Accessed June 10, 2021.

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