Management of patients susceptible to malignant hyperthermia: A surgeon's perspective.

OBJECTIVES: Malignant hyperthermia (MH) susceptibility caries broad implications for the care of pediatric surgical patients. While precautions must often be taken for only a vague family history, two options exist to assess MH-susceptibility. We evaluate the use of MH precautions and susceptibility testing at a freestanding children's hospital. METHODS: This single institution retrospective cohort study identified patients of any age who received general anesthetics utilizing MH precautions over a five-year period. The electronic medical record was further queried for patients diagnosed with MH. The indication for MH precautions and uses of susceptibility testing are assessed. Secondary outcomes included a diagnosis of bona fide MH. RESULTS: A total of 125 patients received 174 anesthetics with MH precautions at a mean age of 114 months (0-363 months). Otolaryngology was the procedural service most frequently involved in the care of the cohort (n = 45; 26%). A reported personal or family history of MH (n = 102; 59%) was the most common indication for precautions, followed by muscular dystrophy (n = 29; 17%). No MH events occurred in the cohort and further review of ICD-9 and -10 diagnosis codes found no MH diagnoses. No study subjects received muscle biopsy and contracture testing and only 5 (4%) underwent genetic testing for genomic variants known to cause MH susceptibility. A case example is given to highlight the implications of a reported MH history. CONCLUSION: Otolaryngologists should maintain a familiarity with the precautions necessary to manage patients at risk for MH and MH-like reactions. Without an accessible test to rule out susceptibility, surgeons must rely on a careful history to appropriately utilize precautions. An inappropriate label of "MH-susceptible" may result in decreased access to care and treatment delays.

Early Adverse Events Following Pediatric Mandibular Advancement: Analysis of the ACS NSQIP-Pediatric Database.

OBJECTIVE: This study aims to assess early adverse events and patient factors associated with complications following mandible distraction osteogenesis (MDO). MATERIALS AND METHODS: The American College of Surgeons National Surgical Quality Improvement Program-Pediatric (NSQIP-Pediatric) database, years 2012 to 2019, was queried for patients undergoing mandible advancement via relevant Current Procedural Terminology and postoperative diagnosis codes. Thirty-day adverse events and co-morbidities are assessed. RESULTS: A total of 208 patients were identified with 17.3% (n = 36) experiencing an adverse event, reoperation (n = 14), and readmission (n = 11) being most common. Patients < 365 days old at the time of operation were more likely to experience an adverse event (26.1% vs 10.8%; P = .005). However, among patients less than 1 year of age, differences in the complication rates between patients ≤ 28 days and >28 days (30.2% vs 22.2%; P = .47) and those weighing ≤ 4 kg and >4 kg (31.7% vs 11.5%; P = .063) did not reach statistical significance. CONCLUSIONS: Adverse events following mandible advancement are relatively common, though often minor. In our analysis of the NSQIP-Pediatric database, neonatal age ( ≤ 28 days) or weight ≤ 4 kg did not result in a statistically significant increase in complications among patients less than 1 year of age. Providers should consider early intervention in patients who may benefit from MDO.

Remission of Mucosal Melanoma of the Middle Ear and Petrous Temporal Bone and Reversal of Cranial Nerve Paresis Following Radiation and Single Agent Nivolumab: Clinical Capsule and Review of the Literature.

OBJECTIVE: We report disease remission and recovery of fifth and seventh nerve paresis in a case of primary mucosal melanoma of the middle ear and petrous temporal bone. PATIENT: A 74-year-old man developed sudden, profound, right sided sensorineural hearing loss, disequilibrium, otalgia, and cranial nerve V and VII dysfunction. Imaging demonstrated an unresectable, osteolytic lesion involving the middle ear and anterior petrous apex. Melanoma was diagnosed via in-office biopsy; whole-body metabolic imaging revealed no other primary site. INTERVENTION: Multidisciplinary management included radiation therapy (30 Gy, 10 fractions) followed by induction (five cycles, q2w) and maintenance nivolumab (six cycles, q3w). MAIN OUTCOME MEASURE: Complete metabolic response of primary site and metastases on imaging, recovery of cranial neuropathies. RESULTS: Following palliative radiation therapy and induction nivolumab, cranial neuropathies resolved. With maintenance-dose nivolumab, primary site and metastases exhibited a complete response. Therapy was stopped at 16 months post-diagnosis. Complete remission was maintained until 22 months after diagnosis. The patient developed a solitary cerebral metastasis which was refractory to radiosurgery and biopsy confirmed melanoma. He expired 2 years, 8 months post-diagnosis. CONCLUSIONS: Mucosal melanoma of the middle ear and petrous temporal bone is exceedingly rare. Management is individualized and surgery is undertaken when possible. Key observations in this case are the complete metabolic response and reversal of cranial nerve neuropathies following radiation and anti-programed cell death receptor ligand 1 therapy. Non-surgical treatment is worthy of study as initial management for similar lesions.

Mapping the BH3 Binding Interface of Bcl-xL, Bcl-2, and Mcl-1 Using Split-Luciferase Reassembly.

The recognition of helical BH3 domains by Bcl-2 homology (BH) receptors plays a central role in apoptosis. The residues that determine specificity or promiscuity in this interactome are difficult to predict from structural and computational data. Using a cell free split-luciferase system, we have generated a 276 pairwise interaction map for 12 alanine mutations at the binding interface for three receptors, Bcl-xL, Bcl-2, and Mcl-1, and interrogated them against BH3 helices derived from Bad, Bak, Bid, Bik, Bim, Bmf, Hrk, and Puma. This panel, in conjunction with previous structural and functional studies, starts to provide a more comprehensive portrait of this interactome, explains promiscuity, and uncovers surprising details; for example, the Bcl-xL R139A mutation disrupts binding to all helices but the Bad-BH3 peptide, and Mcl-1 binding is particularly perturbed by only four mutations of the 12 tested (V220A, N260A, R263A, and F319A), while Bcl-xL and Bcl-2 have a more diverse set of important residues depending on the bound helix.