Fibrodysplasia ossificans progressiva

Contemporary perspectives on heterotopic ossification

Heterotopic ossification (HO) is the formation of ectopic bone that is primarily genetically driven (fibrodysplasia ossificans progressiva [FOP]) or acquired in the setting of trauma (tHO). HO has undergone intense investigation, especially over the last 50 years, as awareness has increased around improving clinical technologies and incidence, such as with ongoing wartime conflicts. Current treatments for tHO and FOP remain prophylactic and include NSAIDs and glucocorticoids, respectively, whereas other proposed therapeutic modalities exhibit prohibitive risk profiles. Contemporary studies have elucidated mechanisms behind tHO and FOP and have described new distinct niches independent of inflammation that regulate ectopic bone formation. These investigations have propagated a paradigm shift in the approach to treatment and management of a historically difficult surgical problem, with ongoing clinical trials and promising new targets.

Activin A does not drive post-traumatic heterotopic ossification

Heterotopic ossification (HO), the formation of ectopic bone in soft tissues, has been extensively studied in its two primary forms: post-traumatic HO (tHO) typically found in patients who have experienced musculoskeletal or neurogenic injury and in fibrodysplasia ossificans progressiva (FOP), where it is genetically driven. Given that in both diseases HO arises via endochondral ossification, the molecular mechanisms behind both diseases have been postulated to be manifestations of similar pathways including those activated by BMP/TGFβ superfamily ligands. A significant step towards understanding the molecular mechanism by which HO arises in FOP was the discovery that FOP causing ACVR1 variants trigger HO in response to activin A, a ligand that does not activate signaling from wild type ACVR1, and that is not inherently osteogenic in wild type settings. The physiological significance of this finding was demonstrated by showing that activin A neutralizing antibodies stop HO in two different genetically accurate mouse models of FOP. In order to explore the role of activin A in tHO, we performed single cell RNA sequencing and compared the expression of activin A as well as other BMP pathway genes in tHO and FOP HO. We show that activin A is expressed in response to injury in both settings, but by different types of cells. Given that wild type ACVR1 does not transduce signal when engaged by activin A, we hypothesized that inhibition of activin A will not block tHO. Nonetheless, as activin A was expressed in tHO lesions, we tested its inhibition and compared it with inhibition of BMPs. We show here that anti-activin A does not block tHO, whereas agents such as antibodies that neutralize ACVR1 or ALK3-Fc (which blocks osteogenic BMPs) are beneficial, though not completely curative. These results demonstrate that inhibition of activin A should not be considered as a therapeutic strategy for ameliorating tHO.

General anesthesia for dental procedures in patients with fibrodysplasia ossificans progressiva: a review of 42 cases in 30 patients

BACKGROUND

Fibrodysplasia ossificans progressiva (FOP) is a rare genetic condition characterized by progressive heterotopic ossification of skeletal muscle and soft connective tissues, leading to progressive ankylosis of all joints of the axial and appendicular skeleton. Cervical spine fusion, ankylosis of the temporomandibular joints, thoracic insufficiency syndrome, restrictive chest wall disease, and sensitivity to oral trauma complicate airway management and anesthesia and pose life-threatening risks.

METHODS

We conducted a retrospective chart review at 1 institution of patients with FOP who underwent general anesthesia (GA) for dental procedures.

RESULTS

Thirty patients underwent 42 general anesthetics. In 35 of 42 cases, GA was induced after the airway was secured by an awake fiberoptic intubation. In 4 of 42 cases, all of them pediatric, GA was first induced with maintenance of spontaneous ventilation, and the trachea was then intubated using a fiberoptic scope. In 2 cases, 1 adult and 1 pediatric, GA was first induced, and the trachea was then intubated using a GlideScope. In 1 case, the patient had a cuffed tracheostomy device in place that was accessed for GA. In 36 of 42 cases, the patients were discharged home on the same day as their dental procedure. No significant postoperative complications were encountered.

CONCLUSIONS

GA can be administered safely to patients with FOP for dental procedures with attention to perioperative and airway management using a multidisciplinary approach. An awake nasal fiberoptic intubation should be considered the first choice for airway management. Most patients can be discharged home on the same day as their dental procedure.

Anaesthetic management of a child with fibrodysplasia ossificans progressiva

Fibrodysplasia Ossificans Progressiva (FOP) is a rare inherited disease in which progressive ossification of striated muscles leads to severe disability and respiratory impairment early in life and there are associated characteristic congenital skeletal malformations. Although this condition may prove demanding for the anaesthetist, few reports are available regarding anaesthesia in paediatric patients. We review the clinical features of the disease relevant to anaesthesia and describe the perioperative care of an 18-month-old boy with FOP who underwent endoscopic third-ventriculostomy for hydrocephalus associated with a brainstem mass. We emphasize the importance of an appropriate anaesthetic management of these patients, as inadequate care may lead to exacerbation of the disease with permanent sequelae.

Anesthesia in a child with fibrodysplasia ossificans progressiva

We describe the anesthesia management of a 12-year-old girl, diagnosed with fibrodysplasia ossificans progressiva (FOP), who presented with a submandibular abscess. FOP is a rare, inherited disorder with heterotopic bone formation and progressive musculoskeletal disability. This disability ultimately confines patients to a wheelchair. Minor trauma following dental treatment may lead to ankylosis of the jaw. Subsequent to this disability, which resulted in poor dental hygiene, our patient developed a dental abscess. This spread along the mandibular margin and under the tongue. She presented with an impending airway compromise in an already difficult situation. The options for airway management in a child with limited mouth opening are discussed.

Anesthetic management in fibrodysplasia ossificans progressiva (FOP): a case report

Fibrodysplasia ossificans progressiva (FOP) is a rare congenital disorder of connective tissue, which has significant implications on anesthetic management of affected patients, e.g., application of difficult airway algorithm, avoiding any trauma during venous cannulation. FOP has received very limited reviews in the published anesthesia literature. We describe perioperative care of a 21-year-old female with established diagnosis of FOP presenting for hysteroscopy followed by dilatation and curettage. Multiorgan abnormalities of FOP are reviewed and available anesthetic options are analyzed and compared.

Myositis ossificans progressiva: five generations where the disease was exclusively limited to the maxillofacial region. A case report

Myositis ossificans progressiva is an unusual autosomal-dominant inherited disease characterized by congenital malformations and osseous metaplasia of the fascia of the muscles and connective tissue leading to ossification of the relevant area. The case report is remarkable in that eight members of the same family over five generations manifested the exclusive localization of the disease in the maxillofacial region.

Fibrodysplasia (myositis) ossificans progressiva

Fibrodysplasia ossificans progressiva (FOP) is a rare hereditary connective tissue disorder. Patients with FOP develop progressive ossification of muscle and connective tissue associated with pain and disability. Onset is typically in childhood, and congenital anomalies of the feet are an early sign of this condition. Pain and stiffness of the spine or an inflammatory mass are common presenting features of FOP. Involvement of the spine often leads to complete fusion mimicking ankylosing spondylitis. Studies of twins and families suggest that FOP is a genetically inherited autosomal dominant trait with complete penetrance but variable expressivity. While radionuclide imaging and computed tomography are very sensitive for new bone formation and greatly assist the diagnosis of FOP, unfortunately, effective therapy is unavailable. We present twins with FOP and review the clinical, radiographic, and genetic manifestations of this disorder.