OUTCOMES:
Type 1 Neuromuscular Disease* including Spinal Muscular Atrophy* type 1

*NMD

*SMA

 

INTRODUCTION

 

Frequency of Neuromuscular Disease (NMD) Presenting as Floppy Newborns (Newark, New Jersey):

 

Spinal muscular atrophy type 1: 150

Congenital myopathies: 75

Congenital muscular dystrophies: 29

Spinal muscular atrophy type 2: 26/179

Congenital polyneuropathies: 8

Congenital myotonic dystrophy: 8

Glycogen storage disease: 4

Congenital myasthenic syndrome: 3

Carnitine deficiency: 1

Acid maltase deficiency (Pompe's disease): 0

 

Although children with NMD type 1 often present as floppy newborns and are unable to sit up without support, the clinical course for most people with a congenital myopathy (including muscular dystrophy) is milder than that for spinal muscular atrophy (SMA) type 1. As a result:

  • All NMD type 1 patients with paradoxical breathing are placed on sleep noninvasive ventilatory support (NVS).

  • Many patients require part-time NVS throughout childhood.

  • No patients have ever required tracheostomy tubes (even into adulthood) (even if intubated for intercurrent pneumonias and surgical procedures).

 

SMA type 1, when not promptly diagnosed, is the most common cause of sudden infant death syndrome (SIDS). Children with severe SMA type 1 (10-15%) require continuous (C)NVS or continuous tracheostomy mechanical ventilation (CTMV) before 6 months of age.

 

Children with typical SMA type 1 (70-80%) develop acute respiratory failure after 4 months of age. One study reported 13 of 15 patients having a first hospitalization for respiratory failure before 17 months of age when they are no longer protected from respiratory tract infections by maternal antibodies (JBCV214). About 50% of children with typical SMA type 1 will require CNVS before 10 years of age; the other 50% will require it after 10 years of age.

 

As for most children with NMD type 1, virtually all infants with severe and typical SMA type 1 have paradoxical breathing and require pressure-control NVS during sleep to prevent pectus excavatum and promote more normal lung and chest wall growth (JBCV165).

 

Pectus Excavatum

\ˈpek-təs-ˌek-skə-ˈvāt-əm\

A deformity in which several ribs and the sternum grow abnormally, thereby producing a caved-in or sunken appearance of the chest.

 

Children with mild or "super" SMA type 1 (10-15%), which overlaps with SMA type 2, do not develop acute respiratory failure or require gastrostomy tubes (for all nutrition) until after 18 months of age. (Note: All data presented in our publications concerning SMA type 1 exclude the “super” type 1 children.)

 

MANAGEMENT OPTIONS

 

There are 3 management options for SMA type 1 and other type 1 NMDs:

 

1. Abstaining From Treatment

2. Conventional Invasive Tracheostomy Management

3. Noninvasive Management

 

 

OPTION #1: ABSTAINING FROM TREAMENT

 

To neither prevent nor treat respiratory failure and allow the child to die. This is the systematic policy of British and Australian physicians and many other European and American neurologists, who state that the child is a burden on both the family and the society. Since parents are biased by their love for their child, it is up to unbiased physicians to cease treatment and convince parents to agree with them. In option #1, all children with severe and typical SMA type 1 are dead by 18 months of age with the great majority dead before 9 months of age. Ironically, many of the physicians who insist on “letting nature take its course” are the same ones who conduct research to find treatments and discover cures for SMA. With the arrival of new genetic, stem cell, and other effective treatments for SMA type 1 (and possibly the other SMA types), there may be additional impetus to keep children alive, which can be accomplished for most children with SMA type 1 by noninvasive means (with NVS and mechanical insufflation-exsufflation [MIE]).

 

OPTION #2: CONVENTIONAL INVASIVE TRACHEOSTOMY MANAGEMENT

 

Once the child goes into respiratory failure and is not apparently weanable from ventilator use, in the critical care unit only, 6% of conventional extubation attempts are successful on children with SMA type 1 (JBCV193). As a result, almost all intubations, especially for pneumonia, result in the family being told that tracheotomy is necessary.

 

In a study of 27 children with SMA type 1, CTMV dependent since infancy, 17 were reported to be still alive with a mean age of 78.2 (range 65–179) months. Ten died at a mean 61.6 (range 16–270) months of age. Twenty five of 27 were not able to regain any autonomous breathing ability after the tracheotomy. None of the 21 who had not developed the ability to verbalize before undergoing tracheotomy did so after tracheotomy. Six children had had comprehendible speech at the time of tracheotomy and retained some ability to vocalize subsequently. Thus, typical SMA type 1 patients managed by tracheostomy and CTMV from infancy do not develop speech and permanently lose all ability to breathe unaided from the point at which they undergo tracheotomy.

 

Nevertheless, we have had one SMA type 1 CTMV user since 2 months of age survive to age 22 and there may be others who have survived as long or longer. The 22 year old graduated college using only eyegaze technology to communicate. He died of a pneumothorax. Also, NVS managed SMA type 1 children have 0.7 respiratory hospitalizations (intubations) per year to the 3rd birthday and 0.3 per year from ages 3 to 5, which is significantly more than children with tracheostomy tubes. After the 5th birthday, the hospitalization rates decrease to about 0.1 per year and are about the same for both TMV and NVS users (JBCV193). An advantage of tracheotomy is that it is easier to manage intercurrent respiratory tract infections than for NVS users. Because of the greater dependence on respiratory support and failure to develop speech, however, we discourage this invasive option.

 

OPTION #3: NONINVASIVE MANAGEMENT

 

Since sleep nasal NVS is required because of paradoxical breathing, polysomnograms are useless for children with NMD type 1, all of whom require full ventilator support setting NVS (pressure control of about 18 cm H2O) to optimally rest inspiratory muscles during sleep, so that they are stronger during daytime hours and to expand their lungs to promote growth and prevent chest wall deformities (JBCV165). "Cry" vital capacities (VCs) of 50 mL or greater indicate ability for these infants to breathe without ventilator use when awake.

 

 

OUTCOMES OF NONINVASIVE RESPIRATORY MANAGEMENT

FOR SMA TYPE 1 AND OTHER NMD TYPE 1 CONDITIONS

 

Children with typical to severe NMD type 1, including SMA type 1, develop acute respiratory failure and usually require intubation one or more times before 18 months of age. But even when unweanable from ventilator support, they can almost always be extubated without resort to tracheostomy. Few if any of these children ever require tracheostomy tubes for long-term ventilatory support. In two "Centers for Noninvasive Respiratory Management," 66 children with SMA type 1 who began sleep nasal NVS at a mean of 4 (range 1 to 10) months of age due to their paradoxical breathing and used part-time NVS for a mean of 3.6 ± 6.3 years, 37 of them became CNVS dependent, almost half of whom before age 10. Fourteen of the NVS users became CNVS dependent without being hospitalized or developing acute respiratory failure. Twenty-one of the 37 CNVS users are still alive using CNVS so far for a mean 11.1 ± 3.3 years with 5 now over age 20. Three of the five have 0 mL of VC for many years. Since they also have no bulbar-innervated muscle function (cannot speak, eat, or use their throats [glottis] at all) and have no other active movement except for eye movements and yet do not have tracheostomy tubes even at age 20, it is probable that they will never need tracheostomy tubes. Had these patients undergone tracheotomy as infants, it would be expected that they all would have been dependent on CTMV since infancy and would likely have died from complications of the tubes. Also, since these children avoid tracheostomy tubes, about 80% developed the ability to produce some speech and perhaps 20% can speak with fair articulation past 10 years of age and occasionally after age 20.

 

At least 9 part-time NVS users with SMA type 1, however, underwent tracheotomy, 8 when pressured by their local doctors before becoming CNVS dependent and one when recommended by us after multiple cardiopulmonary arrests at home due to mucus plugging and ineffective home MIE use. Four of the 8 who underwent tracheotomy in their locales after having used NVS died within 2 years of undergoing tracheotomy, but the other 4 have been using CTMV for 4.8 ± 3.7 years and are still alive.

 

Thus, parents of children with NMD type 1, including SMA type 1, who become expert in NVS, CNVS, and MIE, and who have the motivation and time to administer these for their children, especially during intercurrent respiratory tract infections at home using the oximetry feedback protocol, can successfully manage their children long-term. Without one or more expert and motivated parents, the children are more likely to survive longer using CTMV with 24 hours per day of nursing care either at home or in nursing facility ventilator units.

 

For the first three years of life, NVS may be more difficult than TMV because when children become sick, they require extensive commitment from the parents to perform round-the-clock intensive MIE, sometimes for as long as weeks. Some parents cannot overcome this challenge. Therefore, on infrequent occasions, patients can get trached. At Centers for Noninvasive Respiratory Management, only 4 out of 150 SMA type 1 patients on NVS (including 66 on CNVS) got trached, and not because of extubation failure.

 

 

EXTUBATION OF CHILDREN WITH SMA TYPE 1

 

By comparison with the only 6% successful conventional (to supplemental O2 or CPAP) extubation rate for children with SMA type 1 that cause clinicans to assume that the intubated children require tracheostomy tubes to survive, through a 2015 publication, 85% (147 of 173) extubation attempts of 126 unweanable children with SMA type 1 have been successful in two centers, not including 5 of 6 more since the last publication as of December 1, 2015 (JBCV193,JBCV235,JBCV144, JBCV153,JBCV197). So, of a total of 126 SMA type 1 patients, some extubated successfully multiple times, only four underwent tracheotomies, three because of inadequate home care and one for having failed three protocol extubation attempts. While this rate is much less than the almost 100% success rate for adults, patients rarely fail 3 extubation attempts, our main indication to resort to tracheotomy. No SMA type 1 patients over age 2 have required tracheotomy for extubation failure (JBCV144,JBCV153,JBCV197,JBCV235). Intubated children with SMA type 1 who failed from one to up to six conventional extubation attempts over periods of weeks to up to 6 months waiting for their insurance to pay for transfer to a Center for Noninvasive Respiratory Management were successfully extubated to CNVS and MIE in some cases in under 24 hours.

 

Unlike SMA type 1, which usually has little if any effect on heart musculature, some myopathic conditions do affect the heart. For severe infantile Pompe disease, for example, besides chronic ventilatory failure, severe cardiomyopathy is common and the main cause of death for these children whether they use CTMV or CNVS. Consider other references for discussions of cardiac management (JBCVBook7,JBCV135).

 

 

DECANULATION OF CHILDREN WITH NMD TYPES 1-3

 

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