Anesthetic Management of a Patient With Ring 18 Syndrome
Ring 18 syndrome or ring chromosome 18 is an extremely rare genetic disorder involving the fusion of the 18th chromosomal ends to form a ring, often with genetic material loss of varying degrees. Although clinical presentation can be extremely variable, characteristic features usually include craniofacial malformations, delayed development, hypotonia, and other skeletal and congenital heart defects. We report the management of a 20-year-old male with ring chromosome 18 who underwent general anesthesia for dental treatment. Clinical manifestations for this patient included intellectual disability, short stature, hypertelorism, flat nasal bridge, micrognathia, a “carp-shaped” mouth, and aortic and pulmonary valve regurgitation. Although mask ventilation and oral intubation were easily performed, nasal intubation was difficult because of rhinostenosis. When providing general anesthesia for a patient with ring chromosome 18, anesthesiologists should evaluate the patient preoperatively for congenital heart defects and prepare for a potential difficult airway.
Ring 18 syndrome or ring chromosome 18 is a rare genetic abnormality, with ∼70 cases reported worldwide. Although patients may rarely present with few, or even lack, apparent symptoms, common clinical manifestations include congenital heart defects, low height, craniofacial abnormalities such as microcephaly and micrognathia, and intellectual disability. Here, we report the general anesthetic management of a patient with ring chromosome 18 for dental treatment.
CASE REPORT
A 20-year-old man (weight 28.8 kg; height 127 cm; body mass index 17.9 kg/m2) with ring chromosome 18 was scheduled for dental treatment including restorations and extractions under general anesthesia due to his intellectual disability. Clinical manifestations of this patient's genetic disorder included aortic and pulmonary valve regurgitation, short stature, hypertelorism, flat nasal bridge, micrognathia, and a “carp-shaped” mouth (Figure). Trismus was not observed, and upon evaluation, his airway was scored a Mallampati class II. An anteroposterior chest radiograph revealed mild cardiomegaly, as evident by the increased cardiothoracic ratio (55%). Echocardiography revealed moderate aortic and pulmonary valve regurgitation, but his ejection fraction was normal (67.5%). At the age of 18 years, he underwent patch closure for an atrial septal defect under general anesthesia with a reportedly difficult tracheal intubation per his mother. However, we were unable to obtain his medical records.
Citation: Anesthesia Progress 68, 3; 10.2344/anpr-68-03-01
Since his noted craniofacial abnormalities and reported difficult tracheal intubation episode indicated the potential for a difficult airway, an oral airway, laryngeal mask airway, video laryngoscope (Glidescope), and flexible fiber-optic scope were prepared before induction. General anesthesia was induced with propofol 50 mg and remifentanil 0.15 μg/kg/min. Because mask ventilation with sevoflurane 1% and oxygen was performed with ease, we administered rocuronium 18 mg. Fortunately, oral intubation was completed without difficulty under direct laryngoscopy using a traditional laryngoscope with a size 3 Macintosh blade. After securing the airway orally, we attempted nasotracheal intubation with 5.0- and 5.5-mm ID tubes. However, rhinostenosis prevented passage of the nasotracheal tubes bilaterally.
To prevent infective endocarditis, flomoxef sodium 1 g was administered intravenously before the surgery. General anesthesia was maintained with sevoflurane 1.5% with oxygen and remifentanil 0.1–0.15 μg/kg/min. To reduce aortic and pulmonary valve regurgitation, his heart rate was kept at greater than 60 bpm. The anesthetic course was uneventful, and extubation was performed without any trouble after the patient was fully awake. No complications were observed during or after general anesthesia.
DISCUSSION
Ring chromosome 18 is caused by deletion of 1 or 2 ends of chromosome 18, which then fuse together, forming a ring-shaped structure. The individual phenotype and severity of ring chromosome 18 depend on the size and location of the deleted chromosomal regions, chromosomal ring stability during cell division, and other factors.1 Patients with ring chromosome 18 usually have pieces of 18p and 18q (short and long chromosome arms) deleted, which can affect the genes encoded in these areas. Therefore, clinical features of ring chromosome 18 overlap with those found in 18p- and/or 18q-deletion syndromes. It is highly likely that general anesthesia will be required for dental treatment on patients with ring chromosome 18, as intellectual disabilities are rather common.
Because craniofacial abnormalities such as microcephaly, micrognathia, a “carp-shaped” mouth, and cleft palate have been reported in patients with ring chromosome 18, the anesthesiologist should be prepared for the potential possibility of difficult airway management.1,2 In this case, micrognathia and a carp-shaped mouth were observed, and the patient had a reported history of difficult intubation, prompting the additional measures. In addition, if there are any clinical findings suggestive of a difficult nasotracheal intubation (eg, rhinostenosis), consideration should be given to first securing the airway orally before attempting nasotracheal intubation.
Congenital heart defects such as pulmonary stenosis and atrial septal defects are also commonly observed in this rare genetic disorder.3 When anesthetizing a patient with ring chromosome 18, a detailed preoperative evaluation including assessment of the patient's cardiovascular function and airway is warranted. The potential for airway management difficulties should also be anticipated.
This case report was originally published in the Journal of the Japanese Dental Society of Anesthesiology (2020;48[3];117–119).
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