Malignant infantile osteopetrosis: otolaryngological complications and management

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.

Brain Abscess in a Patient with Osteopetrosis: A Rare Complication

Brain abscess formation is extremely rare in patients with osteopetrosis. Herein, we report a case of viridans streptococci brain abscess in an immunocompromised child diagnosed with osteopetrosis. The patient presented with a sudden change in mental status and convulsions. Radiological evaluation revealed a temporal lobe brain abscess, and intravenous antibiotherapy was started immediately. The patient underwent abscess drainage, and laboratory investigation of pus material revealed viridans streptococci.

CCDC154 Mutant Caused Abnormal Remodeling of the Otic Capsule and Hearing Loss in Mice

Osteopetrosis is a rare inherited bone disease characterized by dysfunction of osteoclasts, causing impaired bone resorption and remodeling, which ultimately leads to increased bone mass and density. Hearing loss is one of the most common complications of osteopetrosis. However, the etiology and pathogenesis of auditory damage still need to be explored. In this study, we found that a spontaneous mutation of coiled-coil domain-containing 154 (CCDC154) gene, a new osteopetrosis-related gene, induced congenital deafness in mice. Homozygous mutant mice showed moderate to severe hearing loss, while heterozygous or wild-type (WT) littermates displayed normal hearing. Pathological observation showed that abnormal bony remodeling of the otic capsule, characterized by increased vascularization and multiple cavitary lesions, was found in homozygous mutant mice. Normal structure of the organ of Corti and no substantial hair cell or spiral ganglion neuron loss was observed in homozygous mutant mice. Our results indicate that mutation of the osteopetrosis-related gene CCDC154 can induce syndromic hereditary deafness in mice. Bony remodeling disorders of the auditory ossicles and otic capsule are involved in the hearing loss caused by CDCC154 mutation.

Extensive maxillary osteomyelitis following tooth extraction in a patient with osteopetrosis

Osteopetrosis (OP), also known as marble bone disease is an extremely rare inherited skeletal disorder, characterised by abnormal functioning of the osteoclasts that results in incremental bone deposition with lack of normal bone remodelling. This leads to the formation of hard and brittle bone can readily fracture. The compromised quality of marrow tissue with poor vascularity reduces bone healing and increases the risk of infections. The risk of jawbone osteomyelitis in patients with OP is high and invariably involves mandible. Involvement of maxilla is rare and has been sparingly reported in the literature. This paper highlights a case of extensive necrosis of maxilla and mid-face skeleton following tooth extraction in a patient with OP. Review of the English literature identifying 23 previously published reports of maxillary osteomyelitis in patients with OP is also presented. Demographic details, history of tooth extraction, extent of involvement, clinical presentation, imaging finding, treatment provided and the outcome have been discussed.

Carbonic Anhydrase II Deficiency: A Rare Case of Severe Obstructive Sleep Apnea

The term osteopetrosis describes a group of rare hereditary diseases of the skeleton, characterized by an increase in bone density, caused by a defect in the development or function of osteoclasts. It comprises a clinically and genetically heterogeneous conditions ranging from infantile onset life-threatening forms to mildest adult onset forms. "Malignant" osteopetrosis is characterized by bone fragility, short stature, compressive neuropathies, hypocalcaemia, pancytopaenia. The deficiency of carbonic anhydrase II causes a moderate form, presenting classically as a triad of osteopetrosis, renal tubular acidosis (RTA), and cerebral calcification. This condition leads to specific craniofacial dysmorphisms associated with upper airway obstruction that may result in obstructive sleep apnea. Herein we report a case of osteopetrosis with RTA associated with severe OSAS successfully treated with continuous positive airway pressure (CPAP).

Anesthesia Management of a Child with Osteopetrosis

Osteopetrosis is a rare genetic disorder of osteoclast dysfunction leading to anatomical and physiological disorders. We present the anesthesia management for the femur fracture of a 4-year-old girl with malignant infantile type of osteopetrosis. She had a ventriculoperitoneal shunt, impaired motion, visual disturbance, growth failure, facial deformity, heart murmur of moderate tricuspid regurgitation, and left ventricular heart failure, with splenomegaly and severe anemia.

Diagnosis of osteopetrosis in bilateral congenital aural atresia: Turning point in treatment strategy

Aural atresia is a rare congenital malformation of the external and middle ear. There are several syndromic associations of this anomaly with those involving the first and second branchial arches. Occurrence of aural atresia with sclerosing skeletal dysplasia is unknown and has never been reported. The co-existence of a sclerosing dysplasia can make the surgical treatment in aural atresia difficult and risky; and the auditory improvement may not be as expected. Moreover, internal auditory canal narrowing and hence sensorineural hearing loss in sclerosing dysplasia might add to the already existing conductive hearing loss in such patients. In this case report we have described an unknown association of bilateral microtia with sclerosing skeletal dysplasia (autosomal dominant osteopetrosis) and clinical implications of these two conditions occurring together leading to a change in the management plan.

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.

Osteopetrosis: genetics, treatment and new insights into osteoclast function

Osteopetrosis is a genetic condition of increased bone mass, which is caused by defects in osteoclast formation and function. Both autosomal recessive and autosomal dominant forms exist, but this Review focuses on autosomal recessive osteopetrosis (ARO), also known as malignant infantile osteopetrosis. The genetic basis of this disease is now largely uncovered: mutations in TCIRG1, CLCN7, OSTM1, SNX10 and PLEKHM1 lead to osteoclast-rich ARO (in which osteoclasts are abundant but have severely impaired resorptive function), whereas mutations in TNFSF11 and TNFRSF11A lead to osteoclast-poor ARO. In osteoclast-rich ARO, impaired endosomal and lysosomal vesicle trafficking results in defective osteoclast ruffled-border formation and, hence, the inability to resorb bone and mineralized cartilage. ARO presents soon after birth and can be fatal if left untreated. However, the disease is heterogeneous in clinical presentation and often misdiagnosed. This article describes the genetics of ARO and discusses the diagnostic role of next-generation sequencing methods. The management of affected patients, including guidelines for the indication of haematopoietic stem cell transplantation (which can provide a cure for many types of ARO), are outlined. Finally, novel treatments, including preclinical data on in utero stem cell treatment, RANKL replacement therapy and denosumab therapy for hypercalcaemia are also discussed.

Osteomyelitis of the mandible in a patient with osteopetrosis. Case report and review of the literature

Osteopetrosis is a rare hereditary bone disorder presenting with variable clinical features and is characterized by an increase in bone density and reduction of marrow spaces that result from a defect in the function of osteoclasts and, consequently, a decrease in bone turnover. This disease is generally divided into three types: severe infantile malignant autosomal recessive, intermediate mild autosomal recessive, and benign autosomal dominant. The prognosis of the first two types is very poor and is characterized by an early onset, usually within the first decade of life, and early death. The benign-type is characterized by a later onset and a longer life span. Ten percent of osteopetrosis cases develop osteomyelitis that usually involves the mandible. The osteomyelitis is generally caused by tooth extraction or pulpal necrosis. The leading cause of the increased rate of infection is thought to be a lack of adequate bone vasculature. Treatment of osteomyelitis secondary to osteopetrosis is controversial. Treatment regimens include high-dose systemic antibiotics coupled with thorough debridement of necrotic bone and primary closure of soft tissues, if possible. Hyperbaric oxygen has been used for the treatment of chronic osteomyelitis.

Administration of general anaesthesia to a paediatric patient with osteopetrosis

Osteopetrosis is a rare clinical syndrome characterised by the failure of bone resorption and remodelling, which causes multiple anatomical and physiological impairments. Pathological fractures can occur, in addition to, haemathological and metabolic impairments. Our patient was a 9-year-old girl diagnosed with osteopetrosis in the neonatal period. She had severe anaemia, thrombocytopaenia, hypocalcaemia, as well as growth and development delays. In this case report, the administration of general anaesthesia to the patient for a biopsy of the scalp and skull and a partial maxillectomy is presented.

Impaired vibration of auditory ossicles in osteopetrotic mice

In the middle ear, a chain of three tiny bones (ie, malleus, incus, and stapes) vibrates to transmit sound from the tympanic membrane to the inner ear. Little is known about whether and how bone-resorbing osteoclasts play a role in the vibration of auditory ossicles. We analyzed hearing function and morphological features of auditory ossicles in osteopetrotic mice, which lack osteoclasts because of the deficiency of either cytokine RANKL or transcription factor c-Fos. The auditory brainstem response showed that mice of both genotypes experienced hearing loss, and laser Doppler vibrometry revealed that the malleus behind the tympanic membrane failed to vibrate. Histological analysis and X-ray tomographic microscopy using synchrotron radiation showed that auditory ossicles in osteopetrotic mice were thicker and more cartilaginous than those in control mice. Most interestingly, the malleal processus brevis touched the medial wall of the tympanic cavity in osteopetrotic mice, which was also the case for c-Src kinase-deficient mice (with normal numbers of nonresorbing osteoclasts). Osteopetrotic mice showed a smaller volume of the tympanic cavity but had larger auditory ossicles compared with controls. These data suggest that osteoclastic bone resorption is required for thinning of auditory ossicles and enlargement of the tympanic cavity so that auditory ossicles vibrate freely.

Infantile osteomyelitis secondary to malignant osteopetrosis

Osteopetrosis (OP) is a rare congenital disorder (present at birth) in which the bones become over dense. This results from an imbalance between the formation of bone and the resorption of the bone. Thickening of the bones which become abnormally dense due to an inherited defect in bone resorption, the process in which old bone is broken down and removed so that new bone can be added to the skeleton. Osteoclasts are the cells responsible for bone resorption. In osteopetrosis the osteoclasts do not perform normally. This flaw in bone resorption results in bones that are abnormally dense, yet are fragile and easily broken. Osteopetrosis is also known as Albers-Schonberg disease, generalized congenital osteosclerosis, ivory bones, marble bones, osteosclerosis fragilis generalisata. In this article, we have described about the diagnosis and medical and surgical management of osteopetrosis reported case to our hospital.

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.

Maxillomandibular osteomyelitis in osteopetrosis. Report of a case and review of the literature

INTRODUCTION

Osteopetrosis is a rare hereditary group of bony displasias. They range from a devastating metabolic disease (including severe malignant infantile osteopetrosis) to other conditions with a more benign phenotype (autosomal dominant osteopetrosis I and II).

CASE REPORT

Several case reports have been published of infectious complications affecting the mandible but maxillary affectation is quite rare. We present the case of a 23-year-old woman with a malignant recessive form of osteopetrosis complicated by repeated episodes of osteomyelitis (caused by actinomyces) of the mandible and maxilla.

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

Malignant infantile osteopetrosis (MIOP) is a rare disorder caused by dysfunctional osteoclasts. The classic MIOP features, such as frontal bossing, micrognathia, and small thorax, may place these children at risk for developing obstructive sleep apnea (OSA) and chronic hypoxemia. To objectively document OSA, airway evaluations were performed; results impacted management. We reviewed the records of 7 MIOP patients treated at St Jude. Six underwent polysomnograms during prehematopoietic stem cell transplantation (HSCT) evaluation. To determine the existence of a relationship between OSA and radiologic imaging, initial chest radiographs and bone mineral density studies were reviewed. Pre-HSCT patients had a median apnea-hypopnea index of 17.51 (normal, 0 to 2), with <25% being central events, thus indicating OSA. The median minimal oxygen saturation was 79%, indicating intermittent hypoxemia. Neither chest radiographs nor bone mineral density correlated with severity of OSA. Four patients received tracheostomies before or during HSCT. Three surviving children underwent polysomnograms 1 year after HSCT, and median apnea-hypopnea index was 1.3, indicating near to complete resolution of OSA. Resolution of OSA may have been multifactorial. Using a quantitative approach, we demonstrate that MIOP children have OSA and hypoxemia; thus, these children should have airway evaluations and treatments to potentially reduce the risk of life-threatening pulmonary complications.

Expansion cranioplasty with jackscrew distracters for craniosynostosis and intracranial hypertension in transplanted osteopetrosis

BACKGROUND

An 11-month-old boy with autosomal recessive infantile osteopetrosis presented, 7 months after bone marrow transplantation, with normal ventricular size and life-threatening intracranial hypertension due to pansynostosis.

METHODS

The cranial vault was expanded by using jackscrew distracters to upwardly advance the upper part of the calvarium.

RESULTS

The procedure achieved a 15-mm upward expansion of the cranial vault over a 15-day period, and the volume of the cranial vault was increased by 139 ml. All clinical manifestations of intracranial hypertension resolved.

CONCLUSION

Cranial vault expansion with jackscrew distracters was successful in relieving intracranial hypertension in an infant with pancraniosynostosis complicating bone marrow transplanted malignant infantile osteopetrosis.

Otologic manifestations of malignant osteopetrosis

OBJECTIVE

To determine the incidence of hearing loss and describe the neurotologic manifestations over time in a large series of patients with malignant osteopetrosis.

STUDY DESIGN

Longitudinal study.

SETTING

Tertiary care referral center.

PATIENTS

Thirty-two patients, including 19 infants (< 1 yr of age at initial visit) and 13 children (aged 1-7.6 yr at initial visit), with autosomal recessive osteopetrosis were followed-up during a 10-year period from 1991 to 2001. The average length of follow-up was 2.5 years (range, 0-9.1 yr).

INTERVENTIONS

Patients underwent annual otologic evaluations including clinical examination, audiologic evaluation (auditory brainstem response, pure-tone thresholds, speech discrimination scores, and tympanograms), and high-resolution computed tomography of the temporal bone.

MAIN OUTCOME MEASURES

Incidence of hearing loss, otitis media, and facial paralysis. Serial changes in temporal bone anatomy by computed tomographic scan.

RESULTS

Twenty-six percent of infants' ears demonstrated hearing loss during the first year of life, and 78% of children's ears demonstrated hearing loss during the study period. Of the children's ears with hearing loss, 100% had a conductive component and 26% had an additional sensorineural component (mixed hearing loss); VIIIth nerve conduction was normal in 100% of infants and 78% of children. Five patients (16%) had unilateral facial nerve palsy. Common temporal bone findings included thickening and sclerosis of the calvarium; poor pneumatization of the mastoid bone; and narrowing of the external auditory canal, eustachian tube, and internal auditory canal.

CONCLUSION

Otologic manifestations are common in malignant osteopetrosis secondary to the formation of dense, brittle bone. Frequent findings include external auditory canal stenosis, otitis media, conductive and sensorineural hearing loss, and facial nerve paralysis.

Autosomal dominant osteopetrosis and maxillomandibular osteomyelitis

Osteopetroses represent a heterogeneous group of rare, hereditary bony dysplasias. They range from a devastating neurometabolic disease (including severe malignant infantile osteopetrosis) to 2 more benign conditions principally affecting adults: autosomal dominant osteopetrosis (ADO) type I and type II. The present study describes the maxillofacial manifestations associated with the 2 subgroups of ADO. In this paper, we present the oldest patient described in the literature with ADO type I (76 years old). We also document the first ADO type II patient described in the literature with synchronic osteomyelitis of the mandible and the maxilla.

Recalcitrant osteomyelitis following tooth extraction in a case of malignant osteopetrosis

Malignant osteopetrosis generally begins in utero and often results in stillbirth. Besides, failure to thrive, increased bone fragility resulting in frequent fractures and recurrent bone infections are the other characteristic features. Infections after tooth extraction and fracture of the sclerotic bone following mild trauma are serious complications, as these ordinarily common problems are very difficult to treat in such patients. Poor bone vascularisation and reduced local defences prolong the defensive response. A rare case of malignant osteopetrosis in a 19-year-old girl, who presented with the complication of osteomyelitis of the mandible following tooth extraction, is presented. The case is of interest for two reasons: it is very rare for a case of malignant osteopetrosis to survive until adulthood and to be aware of the potential dental and oral complications of the disorder.

Severe pulmonary hypertension: a frequent complication of stem cell transplantation for malignant infantile osteopetrosis

This report describes eight infants who developed acute severe pulmonary arterial hypertension (PAH) at days -2 to +89 after allogeneic stem cell transplantation (SCT) for malignant infantile osteopetrosis (MIOP). They were taken from a total of 28 children (frequency 29%) transplanted for this disease at three institutions between 1996 and 2002. Typical presentations were acute dyspnoea, hypoxia and brady/tachycardia usually in the absence of fever, crepitations or other evidence of infection. Six patients (75%) required assisted ventilation and five (62%) died. There was clinical or pathological evidence of veno-occlusive disease (VOD) in three children, but absence of VOD in the remaining five suggests that a separate disease process may be responsible for the PAH. Responses to nitric oxide (NO), defibrotide (DF), nicardipine and steroids in varying combinations were disappointing. Three children showed sustained improvement after administration of epoprostenol (EP, prostacyclin) in conjunction with NO and/or DF and remain well and free of PAH 25, 31 and 32 months post-transplant. PAH must therefore be excluded in any child who becomes acutely breathless after SCT for osteopetrosis.

Chloride channel ClCN7 mutations are responsible for severe recessive, dominant, and intermediate osteopetrosis

Among 94 osteopetrotic patients presenting with a severe clinical picture and diagnosed early in life, 12 bore mutations in the ClCN7 gene, but only 7 of them had the expected two recessive mutations. The remaining five patients seem to be heterozygous for a ClCN7 mutation, and significant variations were observed in the clinical manifestations of their disease, even within the same family.

INTRODUCTION

Human osteopetroses are a heterogeneous group of diseases that include both infantile severe, autosomal recessive (ARO) and adult autosomal dominant (ADO) forms. Two genes, Atp6a3 (TCIRG1) and ClCN7, have been shown to be associated with human ARO, the latter of which is also thought to be responsible for ADO-II. However, patients with an intermediate phenotype have been described: the genetic basis of these observances is unknown.

MATERIALS AND METHODS

In this study, we report the clinical and molecular analysis of 94 patients in which a diagnosis of severe osteopetrosis was made within the first 2 years of age. Both TCIRG1 and CLCN7 genes were sequenced in all patients and the molecular findings were correlated to clinical parameters.

RESULTS AND CONCLUSIONS

In 56 of 94 patients with a classical picture of ARO, TCIRG1-dependent recessive mutations were found. In contrast, ClCN7 mutations were found in 12 cases (13%) of severe osteopetrosis, but only 7 of them had two recessive mutations identified: in 6 of these 7 cases, central nervous system manifestations were noted, and these patients had a poor prognosis. The remaining five cases were heterozygous for a ClCN7 mutation, including two brothers from a large family with a history of ADO-II in which the presence of a second ClCN7 mutation was formally excluded. Despite an early and severe clinical presentation, these five patients all reached adulthood, suggesting that the degree of dominant interference with chloride channel function can vary widely. Our findings suggest that recessive ClCN7-dependent ARO may be associated with CNS involvement and have a very poor prognosis, whereas heterozygous ClCN7 mutations cause a wide range of phenotypes even in the same family, ranging from early severe to nearly asymptomatic forms. These findings have prognostic implications, might complicate prenatal diagnosis of human osteopetroses, and could be relevant to the management of these patients.

Neurological aspects of osteopetrosis

The osteopetroses are caused by reduced activity of osteoclasts which results in defective remodelling of bone and increased bone density. They range from a devastating neurometabolic disease, through severe malignant infantile osteopetrosis (OP) to two more benign conditions principally affecting adults [autosomal dominant OP (ADO I and II)]. In many patients the disease is caused by defects in either the proton pump [the a3 subunit of vacuolar-type H(+)-ATPase, encoded by the gene variously termed ATP6i or TCIRG1] or the ClC-7 chloride channel (ClCN7 gene). These pumps are responsible for acidifying the bone surface beneath the osteoclast. Although generally thought of as bone diseases, the most serious consequences of the osteopetroses are seen in the nervous system. Cranial nerves, blood vessels and the spinal cord are compressed by either gradual occlusion or lack of growth of skull foramina. Most patients with OP have some degree of optic atrophy and many children with severe forms of autosomal recessive OP are rendered blind; optic decompression is frequently attempted to prevent the latter. Auditory, facial and trigeminal nerves may also be affected, and hydrocephalus can develop. Stenosis of both arterial supply (internal carotid and vertebral arteries) and venous drainage may occur. The least understood form of the disease is neuronopathic OP [OP and infantile neuroaxonal dystrophy, MIM (Mendelian inheritance in man) 600329] which causes rapid neurodegeneration and death within the first year. Although characterized by the finding of widespread axonal spheroids and accumulation of ceroid lipofuscin, the biochemical basis of this disease remains unknown. The neurological complications of this disease and other variants are presented in the context of the latest classification of the disease.