Case Reports Anesthetic Management in Fibrodysplasia Ossificans Progressiva (FOP): A Case Report Amrik Singh, MD,* Anitha Ayyalapu, MD,* Annette Keochekian, MD† Department of Anesthesiology, Univeristy of California (Davis) Medical Center, Sacramento, CA
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. © 2003 by Elsevier Science Inc. Keywords: Heterotopic ossification; intubation; fiberoptic.
Introduction
*Assistant Professor †Resident Address correspondence to Dr. Singh at the Department of Anesthesiology, UC Davis Medical Center, 4150 V Street, PSSB 1200, Sacramento, CA 95817. E-mail:
[email protected] Received for publication May 28, 2002; revised manuscript accepted for publication September 4, 2002.
Fibrodysplasia ossificans progressiva (FOP) is a rare inherited disorder that involves congenital malformation of the great toes and progressive ossification of connective tissue. The disease causes multiple deformities of the musculoskeletal system, including the airway. A restrictive respiratory dysfunction develops over time. Although surgical removal of heterotopic bone is ineffective and leads to catastrophic exacerbation of the disease, patients with FOP may occasionally require surgery for intercurrent problems. Such surgical procedures present unique challenges to the anesthesiologist. Few reports are available in anesthesiology literature. None of these reports addresses all the anesthetic concerns and their management. For example: 1) the extreme importance of avoiding repeated tissue trauma during venous cannulation and other forms of injection, 2) the ideal approach to use to secure the airway, 3) the use of regional versus general anesthesia, 4) disease initiating/aggravating factors, and 5) the salient features of the disease. Although awake fiberoptic intubation to secure the airway is promoted in previous reports, details about how to perform this procedure safely are not emphasized.1,2 In fact, routine methods used to topicalize the airway may prove disastrous for patients with FOP. We report a case of FOP and describe its anesthetic management.
Journal of Clinical Anesthesia 15:211–213, 2003 © 2003 Elsevier Science Inc. All rights reserved. 655 Avenue of the Americas, New York, NY 10010
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Case Reports
Case Report A 21-year-old female with established diagnosis of FOP presented with menorrhagia and an endometrial mass. She was scheduled to undergo hysteroscopy and dilation and curettage. Past medical history was significant for FOP diagnosed at the age of 10 years. She had two previous operations, including a biopsy of iliopsoas muscle at 10 years and release of hip contracture at age 11. Review of systems revealed menorrhagia, inability to walk due to disabling heterotopic ossification, and no history of recent respiratory infection. Physical examination revealed a well-nourished female in no obvious distress. She was 66 inches tall and she weighed 73 kg. Her neck was completely fused by the disease process and held in permanent flexion. Mouth opening was 5-cm. She had thoracic scoliosis, rib joint fusion, and a diaphragmatic breathing pattern. No abnormalities of the cardiovascular system were found. Her hips were fused at 45-degree flexion and knees at 90-degree flexion. The shoulders and elbows were also ankylosed. Current medications included isotretinoin, citalopram (an antidepressant), and oral contraceptive pills (to decrease uterine bleeding). Anesthetic management: In the preoperative holding area, an 18-gauge peripheral intravenou (IV) line was established. Diazepam 2.5 mg and glycopyrrolate 0.2 mg were given IV. Five mL of 4% lidocaine was administered through nebulized aerosol. The patient was then taken to the operating room and monitors were placed (ECG, automatic blood pressure cuff, and continuous pulse oximeter). Oxygen by facemask was administered and the patient was lightly sedated with an additional 2.5 mg diazepam and propofol infusion at 25 g/kg/min. Airway nerve blocks were intentionally avoided. Fiberoptic bronchoscope (Pentax FB 10X, Lake Success, NY) was introduced through the breakaway oral airway. Under direct vision, the vocal cords and trachea were sprayed with 1 mL of 4% lidocaine through the sideport. The scope was passed into the trachea, and the patient was intubated with 6.5-mm ID endotracheal tube (softened by submerging in warm water). Anesthesia was then maintained with sevoflurane and fentanyl. The patient remained stable during the procedure, which lasted about 2 hours. The patient’s trachea was extubated while she was fully awake, and she was discharged from recovery room in stable condition.
Discussion Fibrodysplasia ossificans progressiva is a very rare disorder that was first described by Guy Patin in 1648. The prevalence is approximately 0.6 per one million, but, to date, fewer than 400 cases have been reported worldwide. FOP is an autosomal dominant disorder with complete penetrance.3 Overexpression of bone morphogenetic protein 4 has been associated with the pathogenesis of the disease.4 The majority of patients initially present at about 4years of age.5 Recognition of the congenital great toe malformation in association with soft tissue lesions is important in early diagnosis of the disease. The clinical 212
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presentation includes widespread heterotopic ossification of muscle, tendons, ligaments, and fascia with ectopic bone formation. It frequently involves neck and spine with progressive ankylosis and eventual confinement to wheelchair (Figure 1A and B). Shoulder, elbow, hip, and knee joints are often ankylosed. Variable size soft tissue nodules in the neck and back are often the first indication of heterotopic ossification in a child.3 Muscles of mastication are progressively fused leading to limited mouth opening, inability to feed orally, with subsequent cachexia and poor oral hygiene Patients develop severe restrictive pulmonary disease because of scoliosis of thoracolumbar spine,6 ankylosis of costovertebral joints, and ossification of chest wall with resulting dependence on diaphragm for ventilation. Lung volumes are severely reduced but flow rates are relatively normal.7 Muscles of larynx, diaphragm, extraocular, abdominal wall, tongue, and face are spared. Because of atelectasis and ineffective cough, recurrent pulmonary infections are common with pneumonia as a common cause of death in the third or fourth decade. Physical examination of the cardiovascular system is unremarkable, but patients may have electrocardiographic evidence of right ventricle dysfunction. In one study, the latter was found to be more prevalent in older patients with longer disease duration, higher hemoglobin, and more impaired pulmonary function.7 Diagnosis is established by clinical and radiographic findings. Computed tomography (CT) scan is often helpful.8 There is no effective treatment available. Steroids, disodium etidronate, and warfarin have been used to halt the progression of disease but with unproven benefit. Isotretinoin may decrease the incidence of heterotopic ossification at uninvolved anatomical sites.9 Appropriate knowledge of the disease process and its triggering events is essential to devise a safe anesthetic plan. Events such as multiple biopsies, trauma, intramuscular injections, and dysfunctional IV catheters can immediately precipitate the heterotopic ossification and exacerbate the disease. Repeated tissue trauma should be avoided during venous cannulation. The importance of avoiding tissue trauma in the form of local anesthetic injections and the presence of anatomical airway abnormalities poses a dual challenge to the anesthesiologist. Regional anesthesia is not preferred because 1) it is technically difficult to perform because of musculoskeletal abnormalities, 2) any form of tissue trauma is to be avoided, and 3) airway should be secured in a more controlled and nonemergent situation. The latter should be secured with Fiberoptic intubation while the patient is awake and spontaneously breathing. Injections of local anesthetics during dental procedures have been documented to pose immediate risk for inciting heterotopic ossification and permanent ankylosis of jaw.10 Hence, local injections to anesthetize the airway (e.g., transtracheal nerve block) should be avoided because it could possibly lead to local ossification and complete airway obstruction in the future. Alternative methods such as nebulized lidocaine and IV sedation should be preferred instead. Nasotracheal intubation is preferred because forceful jaw
Anesthesia in fibrodysplasia ossificans progressiva: Singh et al.
Figure 1. Clinical appearance and skeleton of a man with fibrodysplasia ossificans progressiva. The rigid posture in this 25-year-old man with fibrodysplasia ossificans progressiva was due to ankylosis of the spine, shoulders, and elbows. He died of pneumonia at the age of 40 years. Plates and ribbons of ectopic bone contour the skin over the back and arms (A), and can be seen directly on the skeleton (B). (Courtesy of the American Journal of Human Genetics. Reprinted with permission from the University of Chicago Press.)
opening can lead to catastrophic exacerbation. In the present case, oral intubation was preferred because the patient had adequate mouth opening. Steroids appear to have some benefit in decreasing the acute swelling associated with new flare-ups. The patient’s trachea is extubated when fully awake and adequate ventilation has been established. Vigorous chest physiotherapy and pulmonary toilet is instituted postoperatively. Proper positioning and padding perioperatively is equally important. In summary, we describe the pathophysiology and anesthetic management of patients with a very rare disorder called fibrodysplasia ossificans progressiva.
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