Severe Multilevel Tracheal Stenosis with Significant Twisting in a Patient with Spondylometaphyseal Dysplasia: A Case Report.

Spondylometaphyseal dysplasia (SMD) is a rare genetic disorder affecting skeletal growth and development presenting anesthesiologists with many perioperative challenges. We present a case of a patient found to have multilevel tracheal stenosis due to twisting and folding of his trachea. This was discovered on imaging during a research review of SMD cases at our institution. Structural and functional abnormalities of the trachea have not been reported in SMD. This is the first description of a patient with SMD with severe multilevel tracheal disease requiring tracheal reconstructive surgery.

Tracheal Narrowing and Its Impact on Anesthesia Care in Patients With Morquio A (Mucopolysaccharidosis Type IVA): An Observational Study.

BACKGROUND: Recently, tracheal narrowing has been recognized as a significant comorbid condition in patients with Morquio A, also known as mucopolysaccharidosis IVA. We studied a large cohort of patients with Morquio A to describe the extent of their tracheal narrowing and its relationship to airway management during anesthesia care. METHODS: This is an observational study, collecting data retrospectively, of a cohort of patients with Morquio A. Ninety-two patients with Morquio A syndrome were enrolled, among whom 44 patients had their airway evaluated by computed tomography angiography and had undergone an anesthetic within a year of the evaluation. Our hypothesis was that the tracheal narrowing as evaluated by computed tomography angiography increases with age in patients with Morquio A. The primary aim of the study was to examine the degree of tracheal narrowing in patients with Morquio A and describe the difficulties encountered during airway management, thus increasing awareness of both the tracheal narrowing and airway management difficulties in this patient population. In addition, the degree of tracheal narrowing was evaluated for its association with age or spirometry parameters using Spearman's rank correlation. Analysis of variance followed by the Bonferroni test was used to further examine the age-based differences in tracheal narrowing for the 3 age groups: 1 to 10 years, 11 to 20 years, and >21 years. RESULTS: Patient age showed a positive correlation with tracheal narrowing ( rs= 0.415; 95% confidence interval [95% CI], 0.138-0.691; P = .005) with older patients having greater narrowing of the trachea. Among spirometry parameters, FEF25%-75% showed an inverse correlation with tracheal narrowing as follows: FEF25%-75% versus tracheal narrowing: ( rs = -0.467; 95% CI, -0.877 to -0.057; P = .007). During anesthetic care, significant airway management difficulties were encountered, including cancelation of surgical procedures, awake intubation using flexible bronchoscope, and failed video laryngoscopy attempts. CONCLUSIONS: Clinically significant tracheal narrowing was present in patients with Morquio A, and the degree of such narrowing likely contributed to the difficulty with airway management during their anesthetic care. Tracheal narrowing worsens with age, but the progression appears to slow down after 20 years of age. In addition to tracheal narrowing, spirometry values of FEF25%-75% may be helpful in the overall evaluation of the airway in patients with Morquio A.

Transcranial electric motor evoked potential monitoring during scoliosis surgery in children with cerebral palsy and active seizure disorder: is it feasible and safe?

PURPOSE: Use of spinal cord monitoring in children with cerebral palsy (CP) and neuromuscular scoliosis is challenging. The previous reports suggest low success rates in the setting of CP, and it is unclear if transcranial electric motor evoked potentials (TcMEP) monitoring is contraindicated in patients with an active seizure disorder. The purpose of this study was to determine (1) are patients with CP able to be appropriately monitored with TcMEP? and (2) does TcMEP cause an increase in seizure activity? METHODS: This was an institutional review board-approved retrospective cohort study observing 304 patients from 2011 to 2020. Inclusion criteria included all patients with CP undergoing posterior spinal fusion during this time. Intraoperative data were examined for the ability to obtain monitoring and any intraoperative events. Patients were followed for 3 months postoperatively to determine any increase in seizure activity that could have been attributed to the TcMEP monitoring. RESULTS: Of the 304 patients who were observed, 21% (20.8%) were unable to be monitored due to lacking baseline signals from the extremities. Seventy-seven percent (77.5%) were successfully monitored with TcMEP. For these patients, no increased seizure activity was documented either intra- or postoperatively. CONCLUSION: A high percentage of children (77.5%) with CP were able to be successfully monitored with TcMEP during posterior spinal fusion. Furthermore, the concerns about increased seizure activity after TcMEP were not supported by the data from this cohort. Technical details of successful neuromonitoring in these patients are important and included increased stimulation voltage requirements and latency times. LEVEL OF EVIDENCE: III retrospective comparative study.

Anesthetic Concerns of Children With Skeletal Dysplasia.

Children with skeletal dysplasia present unique challenges for safe anesthetic care including differences in the anatomy of the respiratory system, possibility of cervical spine instability or spinal stenosis, and a unique body habitus. Even seemly routine anesthesia can result in respiratory arrest or spinal cord injury. These complications can largely be avoided by proper planning such as appropriate techniques for the intubation of difficult airways, recognition of cervical instability, neuromonitoring for any anesthesia over an hour in patients with severe spinal stenosis, and preoperative assessment of the trachea and avoidance of neuraxial anesthesia in children with Morquio syndrome.

International Consensus Statement on the diagnosis, multidisciplinary management and lifelong care of individuals with achondroplasia.

Achondroplasia, the most common skeletal dysplasia, is characterized by a variety of medical, functional and psychosocial challenges across the lifespan. The condition is caused by a common, recurring, gain-of-function mutation in FGFR3, the gene that encodes fibroblast growth factor receptor 3. This mutation leads to impaired endochondral ossification of the human skeleton. The clinical and radiographic hallmarks of achondroplasia make accurate diagnosis possible in most patients. However, marked variability exists in the clinical care pathways and protocols practised by clinicians who manage children and adults with this condition. A group of 55 international experts from 16 countries and 5 continents have developed consensus statements and recommendations that aim to capture the key challenges and optimal management of achondroplasia across each major life stage and sub-specialty area, using a modified Delphi process. The primary purpose of this first International Consensus Statement is to facilitate the improvement and standardization of care for children and adults with achondroplasia worldwide in order to optimize their clinical outcomes and quality of life.

Resistance to Neuromuscular Blockade by Rocuronium in Surgical Patients with Spastic Cerebral Palsy.

Individuals with spastic cerebral palsy (CP) often exhibit altered sensitivities to neuromuscular blocking agents (NMBAs) used for surgical intubation. We assessed usage of the NMBA rocuronium in patients with spastic CP and evaluated potential modifiers of dosing including gross motor function classification system (GMFCS) level, birthweight, gestational age, and the use of anticonvulsant therapy. In a case-control study, surgical patients with spastic CP (n = 64) or with idiopathic or non-neuromuscular conditions (n = 73) were enrolled after informed consent/assent. Patient data, GMFCS level, anticonvulsant use, and rocuronium dosing for intubation and post-intubation neuromuscular blockade were obtained from medical records. Findings reveal participants with CP required more rocuronium per body weight for intubation than controls (1.00 ± 0.08 versus 0.64 ± 0.03 mg/kg; p < 0.0001). Dosing increased with GMFCS level (Spearman's rho = 0.323; p = 0.005), and participants with moderate to severe disability (GMFCS III-V) had elevated rocuronium with (1.21 ± 0.13 mg/kg) or without (0.86 ± 0.09 mg/kg) concurrent anticonvulsant therapy. Children born full-term or with birthweight >2.5 kg in the CP cohort required more rocuronium than preterm and low birthweight counterparts. Individuals with CP exhibited highly varied and significant resistance to neuromuscular blockade with rocuronium that was related to GMFCS and gestational age and weight at birth.

Automated Assessment of Thoracic-Abdominal Asynchrony in Patients with Morquio Syndrome.

Morquio syndrome is a rare disease caused by a disorder in the storage of mucopolysaccharides that affects multiple organs, including musculoskeletal, respiratory, cardiovascular, and digestive systems. Respiratory failure is one of the leading causes of mortality in Morquio patients; thus, respiratory function testing is vital to the management of the disease. An automated respiratory assessment methodology using the pneuRIP device and a machine-learning algorithm was developed. pneuRIP is a noninvasive approach that uses differences between thoracic and abdominal movements (thoracic-abdominal asynchrony) during respiration to assess respiratory status. The technique was evaluated on 17 patients with Morquio (9 females and 8 males) between the ages of 2 and 57 years. The results of the automated technique agreed with the clinical assessment in 16 out of the 17 patients. It was found that the inverse cumulative percentage representation of the time delay between the thorax and abdomen was the most critical variable for accurate evaluation. It was demonstrated that the technique could be successfully used on patients with Morquio who have difficulty breathing with 100% compliance. This technique is highly accurate, portable, noninvasive, and easy to administer, making it suitable for a variety of settings, such as outpatient clinics, at home, and emergency rooms.

Tracheal narrowing in children and adults with mucopolysaccharidosis type IVA: evaluation with computed tomography angiography.

BACKGROUND: Mucopolysaccharidosis type IVA (MPS IVA) is characterized by progressive skeletal dysplasia and respiratory issues with difficult airway management during anesthesia. OBJECTIVE: To characterize tracheal abnormalities in children and adults with MPS IVA including interplay of the trachea, vasculature, bones and thyroid at the thoracic inlet. MATERIALS AND METHODS: Computed tomography (CT) angiograms of the chest were analyzed for trachea shape, narrowing and deviation at the thoracic inlet, course of vasculature, bone alignment and thyroid location. The tracheal cross-sectional area was measured at the cervical, thoracic inlet and intrathoracic levels. RESULTS: Thirty-seven patients (mean age: 18.1 years) were included. The mean tracheal cross-sectional area narrowing at the thoracic inlet was 63.9% (range: -2.1-96%), with a trend for increased tracheal narrowing in older children. The trachea was commonly deviated rightward posterior (22/37, 59%). T- or W-shaped tracheas had two times greater tracheal narrowing than D- or U-shaped tracheas (P<0.05). The brachiocephalic artery was tortuous in 35/37 (95%) with direct impingement on the trachea in 24/37 (65%). No correlation was observed between bony thoracic inlet diameter and tracheal narrowing. The thyroid was located in the thoracic inlet in 28/37 (76%) cases, significantly associated with tracheal narrowing (P=0.016). CONCLUSION: Narrowing, deviation and abnormal shape of the trachea at the thoracic inlet are common in children and adults with MPS IVA, with a trend toward increased narrowing with advancing age in children. A W- or T-shaped trachea is associated with focal tracheal narrowing. Crowding of the thoracic inlet, due to vascular tortuosity and thyroid position, appears to play a major role.

Pediatric Airway Management in COVID-19 Patients: Consensus Guidelines From the Society for Pediatric Anesthesia's Pediatric Difficult Intubation Collaborative and the Canadian Pediatric Anesthesia Society.

The severe acute respiratory syndrome coronavirus 2 (coronavirus disease 2019 [COVID-19]) pandemic has challenged medical systems and clinicians globally to unforeseen levels. Rapid spread of COVID-19 has forced clinicians to care for patients with a highly contagious disease without evidence-based guidelines. Using a virtual modified nominal group technique, the Pediatric Difficult Intubation Collaborative (PeDI-C), which currently includes 35 hospitals from 6 countries, generated consensus guidelines on airway management in pediatric anesthesia based on expert opinion and early data about the disease. PeDI-C identified overarching goals during care, including minimizing aerosolized respiratory secretions, minimizing the number of clinicians in contact with a patient, and recognizing that undiagnosed asymptomatic patients may shed the virus and infect health care workers. Recommendations include administering anxiolytic medications, intravenous anesthetic inductions, tracheal intubation using video laryngoscopes and cuffed tracheal tubes, use of in-line suction catheters, and modifying workflow to recover patients from anesthesia in the operating room. Importantly, PeDI-C recommends that anesthesiologists consider using appropriate personal protective equipment when performing aerosol-generating medical procedures in asymptomatic children, in addition to known or suspected children with COVID-19. Airway procedures should be done in negative pressure rooms when available. Adequate time should be allowed for operating room cleaning and air filtration between surgical cases. Research using rigorous study designs is urgently needed to inform safe practices during the COVID-19 pandemic. Until further information is available, PeDI-C advises that clinicians consider these guidelines to enhance the safety of health care workers during airway management when performing aerosol-generating medical procedures. These guidelines have been endorsed by the Society for Pediatric Anesthesia and the Canadian Pediatric Anesthesia Society.

Cochlear implantation in a patient with mucopolysaccharidosis IVA.

Mucopolysaccharidosis IVA (OMIM 253000; also known as Morquio A syndrome) is associated with skeletal, airway, and hearing abnormalities. Cochlear implantation is an effective intervention for patients with severe-to-profound hearing loss. Patients can gain substantial improvement in auditory performance, speech perception, and their quality of life from cochlear implantation. Although severe progressive sensorineural hearing loss is a common feature of mucopolysaccharidosis IVA, no detailed description of cochlear implantation for mucopolysaccharidosis IVA has been reported. To review the effectiveness and special considerations associated with cochlear implantation in patients with mucopolysaccharidosis IVA, we here report the case of cochlear implantation in mucopolysaccharidosis IVA by a multidisciplinary team. A retrospective chart review was conducted on a 34-year-old female with mucopolysaccharidosis IVA, who received a cochlear implant. Audiometric thresholds, speech perception scores, and cochlear implant processor mapping information were reviewed during the first 12 months following cochlear implantation. The results of audiological tests indicate improved hearing thresholds as well as remarkable enhancement of speech perception skills over 12 months of cochlear implant use. Cochlear implantation improved auditory performance in a mucopolysaccharidosis IVA patient with postlingually severe-to-profound sensorineural hearing loss. The benefits of cochlear implantation could be meaningful for other Morquio patients with progressive hearing loss, although the risks of surgery and anesthesia should be carefully considered by a multidisciplinary team of experts during the cochlear implant candidacy process.

Consensus Statement of the Malignant Hyperthermia Association of the United States on Unresolved Clinical Questions Concerning the Management of Patients With Malignant Hyperthermia.

At a recent consensus conference, the Malignant Hyperthermia Association of the United States addressed 6 important and unresolved clinical questions concerning the optimal management of patients with malignant hyperthermia (MH) susceptibility or acute MH. They include: (1) How much dantrolene should be available in facilities where volatile agents are not available or administered, and succinylcholine is only stocked on site for emergency purposes? (2) What defines masseter muscle rigidity? What is its relationship to MH, and how should it be managed when it occurs? (3) What is the relationship between MH susceptibility and heat- or exercise-related rhabdomyolysis? (4) What evidence-based interventions should be recommended to alleviate hyperthermia associated with MH? (5) After treatment of acute MH, how much dantrolene should be administered and for how long? What criteria should be used to determine stopping treatment with dantrolene? (6) Can patients with a suspected personal or family history of MH be safely anesthetized before diagnostic testing? This report describes the consensus process and the outcomes for each of the foregoing unanswered clinical questions.

Critical review of current MPS guidelines and management.

Mucopolysaccharidoses (MPS) are a group of lysosomal storage disorders that impair degradation of glycosaminoglycans (GAG). The specific GAGs that accumulate depend on the type of MPS, leading to unique characteristic clinical features. Development of guidelines for treatment of MPS has traditionally been multifaceted and largely based on palliative care. In the last three decades, hematopoietic stem cell transplantation and enzyme replacement therapy have been developed based on experimental and clinical studies. Guidelines have been established with the accumulation of the clinical data from natural history of the disease and therapeutic consequences, mainly sponsored by pharmaceutical companies. In recent years, committees in three countries, Australia (2015), Japan (2017), and Brazil (2018) have adopted guidelines for the treatment of MPS II, sponsored and authorized by each government. As novel treatments for MPS including substrate reduction therapy, pharmacological chaperone therapy, and gene therapy become clinically available, it is increasingly necessary to establish the optimal guideline for each type of MPS, considering multiple factors including therapeutic efficacy, adverse effects, age, disease stage, prognosis, feasibility and availability of access to treatment, and cost- performance. In this article, we discuss the historical guidelines for specific MPS types and the most recently adopted guidelines for MPS II and propose the development of future guidelines without conflict of interest and bias leading to mutual benefits to all parties including patients and families, professionals, tax payers, and governments.

Molecular genetics and metabolism, special edition: Diagnosis, diagnosis and prognosis of Mucopolysaccharidosis IVA.

Mucopolysaccharidosis IVA (MPS IVA, Morquio A syndrome) is an autosomal recessive disorder caused by the deficiency of N-acetylgalactosamine-6-sulfate sulfatase. Deficiency of this enzyme leads to the accumulation of specific glycosaminoglycans (GAGs), chondroitin-6-sulfate (C6S) and keratan sulfate (KS), which are mainly synthesized in the cartilage. Therefore, the substrates are stored primarily in the cartilage and its extracellular matrix (ECM), leading to a direct impact on bone development and successive systemic skeletal spondylepiphyseal dysplasia. The skeletal-related symptoms for MPS IVA include short stature with short neck and trunk, odontoid hypoplasia, spinal cord compression, tracheal obstruction, obstructive airway, pectus carinatum, restrictive lung, kyphoscoliosis, platyspondyly, coxa valga, genu valgum, waddling gait, and laxity of joints. The degree of imbalance of growth in bone and other organs and tissues largely contributes to unique skeletal dysplasia and clinical severity. Diagnosis of MPS IVA needs clinical, radiographic, and laboratory testing to make a complete conclusion. To diagnose MPS IVA, total urinary GAG analysis which has been used is problematic since the values overlap with those in age-matched controls. Currently, urinary and blood KS and C6S, the enzyme activity of GALNS, and GALNS molecular analysis are used for diagnosis and prognosis of clinical phenotype in MPS IVA. MPS IVA can be diagnosed with unique characters although this disorder relates closely to other disorders in some characteristics. In this review article, we comprehensively describe clinical, radiographic, biochemical, and molecular diagnosis and clinical assessment tests for MPS IVA. We also compare MPS IVA to other closely related disorders to differentiate MPS IVA. Overall, imbalance of growth in MPS IVA patients underlies unique skeletal manifestations leading to a critical indicator for diagnosis.

Natural history of Morquio A patient with tracheal obstruction from birth to death.

Morquio A syndrome (mucopolysaccharidosis IVA, MPS IVA) is a lysosomal storage disease caused by a deficiency of N-acetylgalactosamine-6-sulfate sulfatase, resulting in systemic accumulation of the partially degraded glycosaminoglycans (GAGs), keratan sulfate and chondroitin-6-sulfate. The accumulation of these GAGs leads to distinguishing features as skeletal dysplasia with disproportionate dwarfism, short neck, kyphoscoliosis, pectus carinatum, tracheal obstruction, coxa valga, genu valgum, and joint laxity. In the absence of autopsied cases and systemic analysis of multiple tissues, the pathological mechanism of the characteristic skeletal dysplasia associated with the disease largely remains a question. Here we report an autopsied case of a 23-year-old male with MPS IVA, who developed characteristic skeletal abnormalities by 4 months of age and died of severe tracheal obstruction and hypoventilation originating from respiratory muscle weakness from neurological cord deficit due to cord myelopathy at the age of 23. We analyzed postmortem tissues pathohistologically, including the thyroid, lung, lung bronchus, trachea, heart, aorta, liver, spleen, kidney, testes, humerus, knee cartilage, and knee ligament. Examination of the tissues demonstrated systemic storage materials in multiple tissues, as well as severely ballooned and vacuolated chondrocytes in the trachea, humerus, knee cartilage, and lung bronchus. This autopsied case with MPS IVA addresses the importance of tracheal obstruction for morbidity and mortality of the disease, and the pathological findings contribute to a further understanding of the pathogenesis of MPS IVA and the development of novel therapies.

Best practices in peri-operative management of patients with skeletal dysplasias.

Patients with skeletal dysplasia frequently require surgery. This patient population has an increased risk for peri-operative complications related to the anatomy of their upper airway, abnormalities of tracheal-bronchial morphology and function; deformity of their chest wall; abnormal mobility of their upper cervical spine; and associated issues with general health and body habitus. Utilizing evidence analysis and expert opinion, this study aims to describe best practices regarding the peri-operative management of patients with skeletal dysplasia. A panel of 13 multidisciplinary international experts participated in a Delphi process that included a thorough literature review; a list of 22 possible care recommendations; two rounds of anonymous voting; and a face to face meeting. Those recommendations with more than 80% agreement were considered as consensual. Consensus was reached to support 19 recommendations for best pre-operative management of patients with skeletal dysplasia. These recommendations include pre-operative pulmonary, polysomnography; cardiac, and neurological evaluations; imaging of the cervical spine; and anesthetic management of patients with a difficult airway for intubation and extubation. The goals of this consensus based best practice guideline are to provide a minimum of standardized care, reduce perioperative complications, and improve clinical outcomes for patients with skeletal dysplasia.

Critical Airway Stenosis in an Adolescent Male With Pompe Disease and Thoracic Lordosis: A Case Report.

An adolescent male with late-onset Pompe disease (glycogen storage disease type II) presented with a history of restrictive airway disease and a near-cardiorespiratory arrest during anesthesia for a liver biopsy initially thought to be due to bronchospasm. During a subsequent posterior spinal fusion procedure, he suffered cardiorespiratory arrest resulting in the procedure being aborted. Bronchoscopy performed shortly after resuscitation revealed an undiagnosed narrowing of the distal trachea and bronchi. This is the first description of a patient with late-onset Pompe disease with undiagnosed critical tracheal stenosis due to the progression of thoracic lordosis, which was ultimately relieved by posterior spinal fusion.

Metatropic dysplasia-a skeletal dysplasia with challenging airway and other anesthetic concerns.

BACKGROUND: Metatropic dysplasia is a rare form of skeletal dysplasia requiring multiple anesthetics for surgical and imaging procedures, most of which are orthopedic procedures. We provide centralized care to patients with skeletal dysplasia at our tertiary care pediatric hospital, and we were able to collect the largest number of metatropic dysplasia patients reported to date. AIM: The aim of this retrospective study was to describe and characterize the anesthetic difficulties in this high-risk population. METHODS: Medical charts of all patients with metatropic dysplasia were reviewed to collect data, including anesthetics performed, difficulties, and complications related to the anesthetic care, co-morbid conditions, and related events. RESULTS: Twenty-three patients with metatropic dysplasia underwent 188 anesthetics with 61% of the anesthetics having been administered for orthopedic procedures. Fourteen of 23 (60.8%) progressively became difficult to intubate over the course of their care, with 12 out of 14 having undergone cervical spine fusion. These 14 patients had a total of 133 procedures. Sixty procedures (45.1%) had an airway described as difficult. Glidescope was the difficult airway tool most commonly used (68%) with flexible fiberoptic scope used 12% and Miller or Macintosh blade used 18% of the time. In addition to the airway difficulties, spinal canal narrowing or stenosis was widely prevalent, and no neuraxial anesthetic was performed in any of our patients. CONCLUSION: Difficult airway is the most common co-morbid condition present in patients with metatropic dysplasia, especially if their cervical spine has been fused. Familiarity with the difficulties involving the airway and its management is critical in safe and successful management of anesthesia in this high-risk population.

Mucopolysaccharidosis IVA and glycosaminoglycans.

Mucopolysaccharidosis IVA (MPS IVA; Morquio A: OMIM 253000) is a lysosomal storage disease with an autosomal recessive trait caused by the deficiency of N-acetylgalactosamine-6-sulfate sulfatase. Deficiency of this enzyme leads to accumulation of specific glycosaminoglycans (GAGs): chondroitin-6-sulfate (C6S) and keratan sulfate (KS). C6S and KS are mainly produced in the cartilage. Therefore, the undegraded substrates are stored primarily in cartilage and in its extracellular matrix (ECM), leading to a direct impact on cartilage and bone development, and successive systemic skeletal dysplasia. Chondrogenesis, the earliest phase of skeletal formation, is maintained by cellular interactions with the ECM, growth and differentiation factors, signaling pathways, and transcription factors in a temporal-spatial manner. In patients with MPS IVA, the cartilage is disrupted at birth as a consequence of abnormal chondrogenesis and/or endochondral ossification. The unique skeletal features are distinguished by a disproportional short stature, odontoid hypoplasia, spinal cord compression, tracheal obstruction, pectus carinatum, kyphoscoliosis, platyspondyly, coxa valga, genu valgum, waddling gait, and laxity of joints. In spite of many descriptions of these unique clinical features, delay of diagnosis still happens. The pathogenesis and treatment of systemic skeletal dysplasia in MPS IVA remains an unmet challenge. In this review article, we comprehensively describe historical aspect, property of GAGs, diagnosis, screening, pathogenesis, and current and future therapies of MPS IVA.

Intraoperative Presentation of Malignant Hyperthermia (Confirmed by RYR1 Gene Mutation, c.7522C>T; p.R2508C) Leads to Diagnosis of King-Denborough Syndrome in a Child With Hypotonia and Dysmorphic Features: A Case Report.

We present the novel case report of a child with hypotonia and dysmorphic features who developed malignant hyperthermia (MH) intraoperatively. Neurology workup revealed the presence of a known causative ryanodine receptor (RYR1) mutation for MH, c.7522C>T; p.R2508C. Furthermore, the neurology workup diagnosed the child with King-Denborough syndrome (KDS). This particular mutation has never been documented in a patient with KDS. Atypical presentation of MH is more likely in patients with RYR1-related myopathy. A high index of suspicion for MH in children with myopathy is important. The MH hotline was helpful in the management of this patient when it was called after the initial dose of dantrolene. A neurology consult was essential for the diagnosis of KDS and future care.