Lumbar Fusion in A Patient With Achondroplasia

Abstract

Introduction: Achondroplasia is the most common cause of short-limbed, disproportionate dwarfism. It is an autosomal dominant condition that is caused by variations in the FGFR3 gene, a fibroblast growth factor receptor. Approximately eighty percent of achondroplastic cases are de novo. The remaining are inherited. If both parents have achondroplasia, there is a twenty-five percent chance of offspring suffering from homozygous achondroplasia, which is a lethal condition. There is also a fifty percent chance of offspring having achondroplasia. This gene mutation inhibits proliferation of the chondrocytes, which ultimately causes impaired endochondral bone formation. The disease process is characterized by clinical features such as shortening of the arms and legs, macrocephaly, kyphoscoliosis, and accentuated lumbar lordosis. These features of patients with achondroplasia are known to make spinal surgery and anesthesia especially difficult. Anesthetic complications and difficult airway intubations are due to many different factors that often require the anesthesiologist to take extra consideration into their anesthetic plan. Many times, the use of devices to better help with viewing the airway are essential. Case Description: A 63-year-old female with a history of achondroplasia, osteopenia, lumbar-adjacent segment disease with spondylolisthesis, and previous L4-5 spinal decompression and fusion surgery presented for an extended bilateral L3-4 lumbar fusion due to lumbar stenosis. Pre-operatively, the patient was determined to be an ASA class III and a Mallampati class I. Vascular access with a peripheral IV was obtained, and an arterial line was placed for intra-operative blood pressure monitoring. 100 mg of propofol and 50 mCg of fentanyl were used for induction. 30 mg of rocuronium was used for paralysis. Intubation was achieved with the use of a video laryngoscope. A fiberoptic bronchoscope was immediately available as well. A grade I view with full visualization of the glottis was obtained for successful intubation. The operative period was uneventful. The patient was re-admitted to the hospital one week later for a fluid collection at the surgical site. Discussion: Patients with achondroplasia pose many potential risks when undergoing anesthesia and surgery. For example, obtaining vascular access can be difficult because of lax skin and excess subcutaneous tissue. Ultrasound should be utilized for easier placement when possible. Achondroplastic patients also have more difficult airways than the typical patient. This is due to the many anatomical variations they may have, especially in the face and spine. Commonly, macroglossia, limited neck mobility, and potential atlanto-axial instability are factors that must be taken into consideration. Taking measures such as utilizing video laryngoscope or fiberoptic bronchoscope are beneficial when intubating the patient. In addition, awake intubation with appropriate topical anesthetic and airway blocks can be considered. This provides the physician with real time feedback of any complications that may take place. Shoulder rolls can be used to help provide the patient’s neck with more extension and better open their airway. As was the case with this patient, a secondary method of intubation should be at hand for potentially difficult airways. Cardiorespiratory function may also be impaired. Therefore, patients should be monitored with pressure-controlled ventilation. Ideally, a high respiratory rate and lower tidal volume should be used both intra-operatively and post-operatively. Ventilation post-operatively can be utilized to avoid potential airway edema and pooling of secretions. Finally, patients with achondroplasia may have more anxiety about undergoing anesthesia than other patients. Proper counseling of intra-operative risks and management should be utilized to help reassure the patient.