Airway evaluation and management in 7 children with malignant infantile osteopetrosis before hematopoietic stem cell transplantation

The clinical features of OSTM1-associated malignant infantile osteopetrosis: A retrospective, single-center experience over one decade

Mutation in OSTM1 give rise to the rarest and most lethal subtype of malignant infantile osteopetrosis (MIOP), and an improved understanding of OSTM1-associated MIOP would help with informed decision-making regarding symptom management and early palliative care referral. This retrospective study describes the clinical and laboratory features of patients with a genetic diagnosis of OSTM1 MIOP made between January 2011 and December 2021 in the Department of Pediatrics, Al-Adan Hospital, Kuwait. Twenty-two children had confirmed homozygous deletion in OSTM1 (13 females, nine males). Consanguinity was reported in almost all parents. 72.7% were diagnosed before the age of two months, most commonly incidentally with a high clinical suspicion. All 22 patients developed upper respiratory symptoms, hepatosplenomegaly, poor feeding, and had severe developmental delay. 80% of patients developed pain and/or irritability, and 40.9% were diagnosed with primary seizures. Bone fractures developed in 27% of patients, most likely iatrogenic, and some patients had hernia and gum abnormalities. The mean survival was 10.9 months. The clinical presentation, symptomatology, and mortality of our cohort were compared with other cases of OSTM1 MIOP identified through a comperhensive search of the PubMed database. The findings conclude that OSTM1 MIOP is a multi-systemic disease with distinct clinical features, of which neurological complications are the most severe and include nociplastic pain and irritability. Although orthopedic complications influence the trajectory of most patients with other forms of osteopetrosis, OSTM1 MIOP is driven by its neurological complications. Hence, OSTM1 should be regarded as a neurodegenerative disease with osteopetrosis as a comorbidity that warrants early palliative care referral.

Phenotype-autosomal recessive osteopetrosis

Osteopetrosis (OPT) is a life-threatening disease characterized by increased bone mass caused by diminished osteoclast function/differentiation. The autosomal recessive forms, caused by biallelic variants in implicated genes, usually present in infancy. Without treatment, autosomal recessive OPTs are usually fatal within the first 10 years of life [1]. Here, we review the clinical features and associated pathophysiology of the autosomal recessive OPT. A greater understanding of these rare disorders will advance early diagnosis and optimal management.

How we approach malignant infantile osteopetrosis

Malignant infantile osteopetrosis (MIOP) is a rare hereditary disorder characterized by excessive bone overgrowth due to a defect in bone marrow resorption by osteoclasts. In most cases, hematopoietic stem cell transplantation (HSCT) may correct bone metabolism but the rapidly progressing nature of this condition necessitates early diagnosis and prompt treatment to minimize irreversible cranial nerve damage. The management of patients with MIOP presents many unique challenges. In this review, the clinical management of patients with MIOP is discussed, including diagnosis, preparation for HSCT and special transplant considerations, management of unique HSCT complications, and long-term follow-up.

Survey of the practices of neonatologists in managing neonates believed to be at high risk of sleep disordered breathing

OBJECTIVE

To determine the practices of neonatologists in managing high-risk neonates believed to be at risk of sleep disordered breathing (SDB).

DESIGN

An electronic web-based questionnaire assessing awareness of and current practices for managing neonates predisposed to SDB with conditions like craniofacial anomalies, neuromuscular disorders or airway problems was emailed to 232 neonatologists and neonatal fellows working in Australia and New Zealand (NZ). Additionally, neonatologists were approached directly during the annual Australia and NZ perinatal conference in 2019.

RESULTS

93 neonatologists (40%) responded to the survey. The majority (85%) of the respondents stated that there were no written protocols/criteria for sleep consultation in their unit. We found considerable variations in the threshold for performing tests including oximetry or referring for polysomnography. Most respondents would perform oximetry before referring for a sleep consultation. However, the duration of oximetry varied from 6 to 24 hours and there was no consensus about what is considered abnormal on an oximetry study.

CONCLUSION

Management of SDB is gaining importance in neonatal care because of prolonged length of hospital stay and possible long-term effects of SDB. Responses received suggest a lack of clarity regarding thresholds for referral for treatment of SDB. Likely contributory factors are concerns regarding a lack of long-term outcome data from treatment perceived to be onerous for the family, unsettling to some infants and delaying hospital discharge. To overcome inconsistencies in practice, standardised guidelines for assessing and managing SDB in neonates are needed.

Sleep disordered breathing (SDB) in neonates and implications for its long-term impact

Sleep-disordered breathing (SDB) is a significant cause of morbidity in neonates and young infants. SDB occurs more commonly in preterm infants and in neonates with underlying syndromes. Recent evidence shows that infants with obstructive sleep apnoea (OSA) or SDB have greater health care resource utilization, including longer hospital stay. Management of SDB includes non-invasive ventilation or surgical interventions tailored to the patient. Screening high risk newborns should allow for early diagnosis and timely therapeutic intervention for this population. However, the thresholds for diagnosing SDB and for guiding and implementing treatment in neonates remain unclear. A collective effort is required to standardize the practice worldwide. This article will discuss neonatal sleep physiology and characteristics of neonatal sleep, with an emphasis on the epidemiology and diagnosis of SDB in neonates and its implications for long term outcomes.

Tracheostomy for paediatric obstructive sleep apnoea: A systematic review

OBJECTIVE

To search the international literature (any language) for publications reporting outcomes of tracheostomy performed to treat obstructive sleep apnoea in children.

METHOD

Data sources included: Google Scholar, Cumulative Index to Nursing and Allied Health Literature, Embase, Scopus, and PubMed/Medline. Four authors searched systematically through to 20 January 2018.

RESULTS

A total of 597 studies were screened; 64 were downloaded and 11 met criteria. A total of 196 patients underwent tracheostomy (mean age, 4.2 years; range, newborn to 18 years); 40 had detailed qualitative data and 6 had detailed quantitative data. Apnoea/hypopnoea index showed a 97 per cent reduction (n = 2) and apnoea index showed a 98 per cent reduction (n = 3). Lowest oxygen saturation showed a 34 oxygen saturation point improvement (n = 3). Several patients demonstrated significant improvement in breathing. All identified patients were syndromic, had significant co-morbidities or had severe obstructive sleep apnoea.

CONCLUSION

Based on reports of children who have undergone a tracheostomy, for whom there are pre- and post-operative data, tracheostomy appears to be a successful treatment for obstructive sleep apnoea. However, additional research is recommended given the small number of patients in the literature.

Polysomnography for the diagnosis of sleep disordered breathing in children under 2 years of age

OBJECTIVES

To describe clinical polysomnography (PSG) results, sleep physicians' diagnosis, and treatment of sleep disorder breathing in children less than 2 years of age.

STUDY DESIGN

Retrospective clinical chart review at a pediatric tertiary care center, pediatric sleep laboratory.

SUBJECT SELECTION

Children less than 2 years of age who underwent clinical PSG over a 3-year period.

METHODOLOGY

PSG results and physician interpretations were identified for inclusions. Children were excluded if either PSG results or physician interpretations were unavailable for review. Infants were classified in three age groups for comparison: <6 months, 6-12 months, and >12 months.

RESULTS

Matched records were available for 233 PSGs undertaken at a mean age 11.1 ± 7.0 months; 31% were <6 months, 23% were 6-12 months, and 46% were 12-24 months of age. Infants <6 months showed significant differences on sleep parameters and respiratory indicators compared to other groups. Compared to physician sleep disordered breathing (SDB) classification, current pediatric apnea-hypopnea index (AHI)-based SDB severity classification overestimated SDB severity. Age and obstructive-mixed AHI (OMAHI) were most closely associated with physician identification of SDB.

CONCLUSION

Children <6 months of age appear to represent a distinct group with respect to PSG. Experienced sleep physicians appear to incorporate age and respiratory event frequently when determining the presence of SDB. Further information about clinical significance of apnea in infancy is required, assisted by identification of factors that sleep physicians use to identify SDB in children <6 months of age.

Hematopoietic stem cell transplantation for infantile osteopetrosis

We report the international experience in outcomes after related and unrelated hematopoietic transplantation for infantile osteopetrosis in 193 patients. Thirty-four percent of transplants used grafts from HLA-matched siblings, 13% from HLA-mismatched relatives, 12% from HLA-matched, and 41% from HLA-mismatched unrelated donors. The median age at transplantation was 12 months. Busulfan and cyclophosphamide was the most common conditioning regimen. Long-term survival was higher after HLA-matched sibling compared to alternative donor transplantation. There were no differences in survival after HLA-mismatched related, HLA-matched unrelated, or mismatched unrelated donor transplantation. The 5- and 10-year probabilities of survival were 62% and 62% after HLA-matched sibling and 42% and 39% after alternative donor transplantation (P = .01 and P = .002, respectively). Graft failure was the most common cause of death, accounting for 50% of deaths after HLA-matched sibling and 43% of deaths after alternative donor transplantation. The day-28 incidence of neutrophil recovery was 66% after HLA-matched sibling and 61% after alternative donor transplantation (P = .49). The median age of surviving patients is 7 years. Of evaluable surviving patients, 70% are visually impaired; 10% have impaired hearing and gross motor delay. Nevertheless, 65% reported performance scores of 90 or 100, and in 17%, a score of 80 at last contact. Most survivors >5 years are attending mainstream or specialized schools. Rates of veno-occlusive disease and interstitial pneumonitis were high at 20%. Though allogeneic transplantation results in long-term survival with acceptable social function, strategies to lower graft failure and hepatic and pulmonary toxicity are urgently needed.

Impact of sleep and breathing in infancy on outcomes at three years of age for children with cleft lip and/or palate

STUDY OBJECTIVES

To evaluate the relationship between sleep disordered breathing (SDB) in early infancy and outcomes at 3 years of age in children with cleft lip and/or palate (CL/P).

DESIGN

Observational follow-up study.

SETTING

Multidisciplinary CL/P clinic, tertiary centre.

PARTICIPANTS

Children with CL/P who participated in a study of sleep and breathing in infancy.

MEASUREMENTS AND RESULTS

The families of 52 children were approached for this follow-up study. The children underwent neurocognitive (Bayley Scales of Infant and Toddler Development, Third Edition; BSID-III), quality of life (Infant/Toddler Quality of Life Questionnaire; ITQOL), and growth assessments at 3 years. The families of 33 children (66%) completed follow-up at 36.7 ± 1.4 months. The apnea-hypopnea index (AHI) in infancy was 23.9 ± 18.0 events/h. Mean group BSID-III scores fell within the standardized normal range (10 ± 3) for all domains; however, language scores were lower than control children. Quality of life scores and growth parameter z-scores were similar to published control data. PSG variables in infancy showed significant relationships with outcomes at 3 years of age; lower percentage of AS/REM sleep was associated with lower cognition score; more obstructive events were associated with lower global behavior ITQOL score; and higher number of respiratory events in infancy was associated with lower weight z-score.

CONCLUSION

Neurocognition, quality of life, and growth measures from children with CL/P fall within a normal range; however, scores in the language domain are lower than controls. Sleep and respiratory elements of SDB in infancy appear to modify these outcomes at 3 years of age.

Successful cord blood transplantation in a patient with malignant infantile osteopetrosis and hemophilia

MIOP is a congenital disorder of osteoclast differentiation or dysfunction. Inadequate bone resorption by osteoclasts results in a spectrum of complications including hypocalcemia, osteosclerosis, marrow failure, extramedullary hematopoiesis, hydrocephalus, visual deficits, and eventual mortality. Early diagnosis and timely HCT is a recommended treatment approach for select patients prior to the development of end-organ damage. A comorbid bleeding disorder presents a unique challenge in the setting of MIOP and cord blood HCT given the additional risk factors for bleeding including delayed engraftment, a high risk of developing sinusoidal obstruction syndrome, and potential need for emergent invasive procedures. To our knowledge, this is the first report of a patient with an autosomal recessive form of MIOP who successfully underwent a cord blood HCT complicated by the presence of mild hemophilia A and HCT-related complications including delayed engraftment, sinusoidal obstruction syndrome, and need for multiple invasive procedures (e.g., ventriculostomy, tracheostomy) without clinically significant bleeding. Given the underlying diagnosis of MIOP and need for HCT, the challenge of mitigating the significant risk of bleeding in a patient with a comorbid bleeding disorder is discussed.

Complications of anesthesia for children with malignant infantile osteopetrosis before and after hematopoietic stem cell transplantation

OBJECTIVES AND AIMS

The primary aim was to determine the frequency of anesthetic-related complications for patients with malignant infantile osteopetrosis (MIOP) before and after hematopoietic stem cell transplant (HSCT). The secondary aims were to describe the types of complications that occurred, to determine whether the risk of anesthetic complications was altered by HSCT, and to determine the frequency of difficult intubation.

BACKGROUND

Patients with MIOP undergo HSCT, often in infancy, and anesthesia is frequently required for investigations and procedures associated with transplantation. Although MIOP has adverse implications for anesthetic management, the literature describing the anesthetic management of MIOP patients is limited.

METHODS

A retrospective review of medical and anesthetic records was undertaken between November 2000 and March 2008.

RESULTS

Eleven patients underwent 127 anesthetics. The overall complication rate was 11%. Before HSCT, there were 12 complications in 62 anesthetics (19.3%). After HSCT, there were two complications in 65 anesthetics (3.2%). This difference was not statistically significant. All of the complications were airway or respiratory events. Of the 26 intubations associated with anesthesia, 23 (88.5%) were easy, 1 (3.8%) was moderately difficult, and 2 (7.7%) were difficult.

CONCLUSION

Complications associated with anesthesia for infants and children with MIOP having HSCT are fairly common and are usually airway or respiratory related. Difficult endotracheal intubation is also common.

Characterization and management of hypercalcemia following transplantation for osteopetrosis

Autosomal recessive osteopetrosis (OP) is characterized by insufficient osteoclast activity resulting in defective bone resorption and marked increase in skeletal mass and density. OP has been successfully treated with hematopoietic cell transplantation (HCT), secondary to engraftment of donor-derived functioning osteoclasts resulting in remodeling of bone and establishment of normal hematopoiesis. Although hypercalcemia is a common presenting feature of OP, it may be observed following HCT due to engraftment of osteoclasts differentiated from the hematopoietic precursors. To characterize hypercalcemia after HCT-who is at risk, onset, duration and response to treatment-we evaluated 15 patients with OP treated at the University of Minnesota from 2000 to 2009. Hypercalcemia, defined as any single calcium >11.0 mg/100 ml after the first transplant, was found in 40% of patients. Median onset of hypercalcemia was 23 days and the duration was 2-24 days. Hypercalcemia was more common in patients older than 2 years of age at the time of HCT. Treatment with hydration, furosemide and s.c. calcitonin resolved hypercalcemia and resulted in no severe adverse events. In conclusion, hypercalcemia is common in patients with OP within the first 4 weeks after HCT, and more likely in older patients. Isotonic saline, furosemide and s.c. calcitonin were well-tolerated and effective treatments in our study population.