Retrospective analysis of referrals for hypoxic challenge testing in children born preterm.

INTRODUCTION: Children with a history of bronchopulmonary dysplasia (BPD) may be at risk of hypoxaemia at altitude, such as during air travel. We have performed preflight hypoxic challenge testing (HCT) since 2006, incorporating British Thoracic Society (BTS) guidance since 2011, to determine which children may require oxygen during air travel. AIMS: We aimed to compare the outcome of HCTs in children with a history of BPD who met the 2011 BTS criteria and those who did not and, in addition to this, to interrogate the data for factors that may predict the outcome of HCT in this population. METHODS: We performed a retrospective analysis of data from HCTs of children with a history of BPD referred 2006-2020. Cases were excluded if the patient had a respiratory comorbidity, was still on oxygen therapy, if the test was a repeat or if the clinical record was incomplete. Descriptive and univariate analysis of the data was performed, and a binary logistic regression model was fitted. RESULTS: There were 79 HCTs, of which 24/79 (30%) did not meet BTS 2011 guidelines referral criteria. The analysis showed a greater proportion of desaturation in the group that did not meet criteria: 46% vs 27% (no statistical significance). Baseline oxygen saturations were higher in those who did not require oxygen during HCT and this variable was significant when adjusted for confounders. CONCLUSIONS: This study found that the current criteria for referral for preflight testing may incorrectly identify those most at risk and highlights the need for further investigation to ensure those most at risk are being assessed prior to air travel.

Stroke-Related Visceral Alterations: A Voxel-Based Neuroanatomic Localization Study.

OBJECTIVE: Functional and morphologic changes in extracranial organs can occur after acute brain injury. The neuroanatomic correlates of such changes are not fully known. Herein, we tested the hypothesis that brain infarcts are associated with cardiac and systemic abnormalities (CSAs) in a regionally specific manner. METHODS: We generated voxelwise p value maps of brain infarcts for poststroke plasma cardiac troponin T (cTnT) elevation, QTc prolongation, in-hospital infection, and acute stress hyperglycemia (ASH) in 1,208 acute ischemic stroke patients prospectively recruited into the Heart-Brain Interactions Study. We examined the relationship between infarct location and CSAs using a permutation-based approach and identified clusters of contiguous voxels associated with p < 0.05. RESULTS: cTnT elevation not attributable to a known cardiac reason was detected in 5.5%, QTc prolongation in the absence of a known provoker in 21.2%, ASH in 33.9%, and poststroke infection in 13.6%. We identified significant, spatially segregated voxel clusters for each CSA. The clusters for troponin elevation and QTc prolongation mapped to the right hemisphere. There were 3 clusters for ASH, the largest of which was in the left hemisphere. We found 2 clusters for poststroke infection, one associated with pneumonia in the left and one with urinary tract infection in the right hemisphere. The relationship between infarct location and CSAs persisted after adjusting for infarct volume. INTERPRETATION: Our results show that there are discrete regions of brain infarcts associated with CSAs. This information could be used to bootstrap toward new markers for better differentiation between neurogenic and non-neurogenic mechanisms of poststroke CSAs. ANN NEUROL 2023;94:1155-1163.

'It gives me more freedom': Family perspectives on travelling with children on nocturnal ventilation.

BACKGROUND: Children with neuromuscular weakness or central hypoventilation often require nocturnal ventilation. Children with these conditions are living longer and the numbers of children affected are increasing. The challenges associated with managing ventilation at home have been documented; however, there has been limited investigation into accessing wider experiences such as travel. Air travel, in particular, may be considered challenging for children with these conditions because oxygen levels are lower in airplane cabins than at sea levels. OBJECTIVE: We sought to understand experiences of and attitudes towards travel amongst families of children using nocturnal ventilation for neuromuscular weakness or central hypoventilation. METHODS: Two semi-structured interviews were conducted amongst participants enrolled in a trial of a new pre-flight assessment of their tolerance of reduced oxygen levels during flight (known as a hypoxic challenge test). Children participating in the trial were aged 19 months to 18 years. Parents were interviewed and provided proxy views for younger children, and older children were encouraged to present their own views during these interviews. One interview was conducted immediately after the assessment, and a second 3 months later. Data were analysed utilising the framework approach to thematic analysis. RESULTS: Seventeen families participated in the first interview with 14 of these families completing the follow-up interview. Three further families participated in the follow-up interview only. Here, we report three themes relating to participant experience of travel and how this is impacted by their condition. The three themes and their sub-themes were (1) insight into children's lives: hospital attendances, gaining knowledge and confidence, and child as a person; (2) travelling with your child: planes, trains and automobiles, rules of air travel, and uncertainty; and (3) the meaning of travel: normalisation, connection to extended family, expanded experiences, and freedom and equality. CONCLUSIONS: This population of children and their families aspire to travel but face challenges from clinical and social barriers. It is essential that we further our understanding of the physiological, social and cultural aspects of their experience to facilitate their access to broadened life experiences.

Morning report: how to do it.

Morning report is an important clinical learning activity in many neurological institutions. A long experience of these meetings allows identification of several components to enhance its success. Meetings are best if brief (one or two cases) and held regularly, preferably daily and early in the working day, with full in-person team engagement. A senior clinician should lead the meeting and commit to a single interpretation, without fear of being wrong. Although the environment is relaxed (refreshments typically provided), it is a working meeting and with the essential focus on the patient rather than the learners. The rich learning experience is greatly enhanced by a subsequent confidential email summary and interpretation of the case(s) sent to all participants.

Screening for sleep-disordered breathing with Pediatric Sleep Questionnaire in children with underlying conditions.

The Pediatric Sleep Questionnaire described by Chervin et al. (Sleep Medicine, 2000, 1, 21-32) was originally validated for children with obstructive sleep apnoea syndrome but without other disorders. The aim of our study was to check the applicability of this questionnaire in children with underlying chronic medical conditions. Children aged 2-18 years who underwent a diagnostic sleep study at Great Ormond Street Hospital were recruited over a 10-month period. The Pediatric Sleep Questionnaire completed by their parents and cardiorespiratory polygraphy were scored. Sensitivities and specificities of the Pediatric Sleep Questionnaire were calculated using a Pediatric Sleep Questionnaire score of 0.33 as being indicative of sleep-disordered breathing. A total of 561 patients were reviewed. Neuromuscular disorders (n = 108), craniofacial anomalies (n = 58) and the obstructive sleep apnea syndrome control group (n = 155) were best represented. The sensitivity for patients with isolated obstructive sleep apnoea syndrome was 76.5% when using an apnoea-hypopnoea index ≥ 5, but this was much lower when looking at specific sub-groups such as neuromuscular patients (25%) or patients with Trisomy 21 (36.7%). Sensitivities remained unchanged for patients with obstructive sleep apnoea syndrome (77.3%) when an apnoea-hypopnoea index of ≥ 1 was used, but improved for neuromuscular disorders sub-groups (36.7%) and Trisomy 21 (84%). In conclusion, the Pediatric Sleep Questionnaire is not a good screening tool for obstructive sleep apnoea syndrome in children with complex underlying disorders when a cut-off apnoea-hypopnoea index of ≥ 5 is used, and it cannot replace cardiorespiratory polygraphy recording.

Learning from history: Lord Brain and Hashimoto's encephalopathy.

We present two historic cases of severe encephalopathy associated with antithyroid antibodies. The first was published by Lord Brain of Eynsham, and the second was from our department's archives. Although both cases are from archival sources, they continue to inform current clinical care. We briefly review the poorly defined entity, Hashimoto's encephalopathy, and discuss diagnostic advances for autoimmune encephalopathy and for Creutzfeldt-Jakob disease. We advocate for giving a trial of corticosteroids to patients with 'encephalopathy, not otherwise specified' while awaiting antibody results or more definitive testing. Our case, initially diagnosed as having Creutzfeldt-Jakob disease, responded remarkably (with video evidence) to a trial of corticosteroids.

The Effect of Midface Advancement Surgery on Obstructive Sleep Apnoea in Syndromic Craniosynostosis.

BACKGROUND: Children with syndromic craniosynostosis frequently suffer from obstructive sleep apnoea (OSA). The aim of the authors' study was to investigate if midface advancement surgery for patients with SC improved the severity of OSA by examining the results of sleep studies before and after surgery. METHODS: A retrospective comparison of the pre and postoperative sleep study data of children undergoing midface advancement surgery at Great Ormond Street Hospital between 2007 and 2016. RESULTS: A total of 65 children underwent midface advancement surgery between 2007 and 2016 at Great Ormond Street Hospital and had recorded pre- and postoperative sleep studies. Thirteen patients were excluded from the analysis as their sleep study techniques before and after surgery were not comparable (e.g., different conditions with prong/continuous positive airway pressure use). Fifty-six percent of the patients were treated by monobloc surgery and the remainder with bipartition surgery. A greater proportion of patients had a normal OSA grading following midface advancement (42.3% postoperatively vs. 23.1% preoperatively, P = 0.059) although no statistically significant categorical changes in OSA grade were observed. Seventy-one percent of the patients had a decrease in Apnoea-Hypopnoea Index after surgery (21 patients 2011 onward). Similarly, there was no significant change in median oxygen desaturation index or in oxygen saturation nadir following surgery. CONCLUSION: The authors report one of the largest reviews of the effects of midface advancement surgery on sleep study parameters. Most patients showed improvements in Apnoea-Hypopnoea Index and OSA grading, although measures of oxygenation showed no consistent change.

Brain MRS glutamine as a biomarker to guide therapy of hyperammonemic coma.

Acute idiopathic hyperammonemia in an adult patient is a life-threatening condition often resulting in a rapid progression to irreversible cerebral edema and death. While ammonia-scavenging therapies lower blood ammonia levels, in comparison, clearance of waste nitrogen from the brain may be delayed. Therefore, we used magnetic resonance spectroscopy (MRS) to monitor cerebral glutamine levels, the major reservoir of ammonia, in a gastric bypass patient with hyperammonemic coma undergoing therapy with N-carbamoyl glutamate and the ammonia-scavenging agents, sodium phenylacetate and sodium benzoate. Improvement in mental status mirrored brain glutamine levels, as coma persisted for 48h after plasma ammonia normalized. We hypothesize that the slower clearance for brain glutamine levels accounts for the delay in improvement following initiation of treatment in cases of chronic hyperammonemia. We propose MRS to monitor brain glutamine as a noninvasive approach to be utilized for diagnostic and therapeutic monitoring purposes in adult patients presenting with idiopathic hyperammonemia.

The neurology of Sjogren's syndrome and the rheumatology of peripheral neuropathy and myelitis.

Neurological symptoms occur in approximately 20% of patients with Sjögren's syndrome, and may be the presenting manifestations of the disease. Here, we review several neurological conditions that can occur in Sjögren's syndrome: sensory ganglionopathy, painful small fibre neuropathy, and transverse myelitis (independently or as part of neuromyelitis optica). We present the symptoms, signs, differential diagnoses, recommended diagnostic evaluation, and treatment of each of these, highlighting the features that should alert neurologists to consider Sjögren's syndrome.

Role of overnight oximetry in assessing the severity of obstructive sleep apnoea in typically developing children: a multicentre study.

BACKGROUND AND OBJECTIVE: Cardiorespiratory polygraphy (CRP) is the predominant technology used to diagnose obstructive sleep apnoea (OSA) in tertiary centres in the UK. Nocturnal pulse oximetry (NPO) is, however, cheaper and more accessible. This study evaluated the ability of NPO indices to predict OSA in typically developing (TD) children. METHODS: Indices from simultaneous NPO and CRP recordings were compared in TD children (aged 1-16 years) referred to evaluate OSA in three tertiary centres. OSA was defined as an obstructive apnoea-hypopnoea index (OAHI) ≥1 event/hour. Receiver operating characteristic curves assessed the diagnostic accuracy of NPO indices including ODI3 (3% Oxygen Desaturation Index, ODI4 (4% Oxygen Desaturation Index), delta 12 s index and minimum oxygen saturation. Two-by-two tables were generated to determine the sensitivities and specificities of whole number cut-off values for predicting OAHIs ≥1, 5 and 10 events/hour. RESULTS: Recordings from 322 TD children, 197 male (61.2%), median age 4.9 years (range 1.1-15.6), were reviewed. OAHI was ≥1/hour in 144 (44.7%), ≥5/hour in 61 (18.9%) and ≥10/hour in 28 (8.7%) cases. ODI3 and ODI4 had the best diagnostic accuracy. ODI3 ≥7/hour and ODI4 ≥4/hour predicted OSA in TD children with sensitivities/specificities of 57.6%/85.4% and 46.2%/91.6%, respectively. ODI3 ≥8/hour was the best predictor of OAHI ≥5/hour (sensitivity 82.0%, specificity 84.3%). CONCLUSION: Raised ODI3 and ODI4 predict OSA in TD children with high specificity but variable sensitivity. NPO may be an alternative to diagnose moderate-severe OSA if access to CRP is limited. Low sensitivities to detect mild OSA mean that confirmatory CRP is needed if NPO is normal.

Modified hypoxic challenge testing in children needing nocturnal ventilation: An observational study.

BACKGROUND: Guidelines for air passengers with respiratory disease focus on primary lung pathology. Little evidence exists to guide professionals advising children needing ventilatory support because of neuromuscular or central hypoventilation conditions; these children might risk hypoxia and hypercapnia if unable to mount an adequate hyperventilation response. OBJECTIVE: This study assessed the response to low ambient oxygen using a modified hypoxic challenge test. In addition to measuring pulse oximetry and response to supplementary oxygen, we also measured transcutaneous carbon dioxide and response to ventilatory support. METHODS: Twenty children on nocturnal ventilatory support aged 1.6-18 years were recruited in a pragmatic sample from outpatient clinics; 10 with neuromuscular weakness and 10 with central hypoventilation. Participants underwent a two-stage, modified hypoxic challenge test; a conventional stage, where oxygen alone was titrated according to SpO2, and a new stage, where participants used their routine ventilatory support with oxygen titrated if needed. Participants were interviewed to understand their experiences of testing and of air travel. RESULTS: Thirteen participants needed supplemental oxygen during the conventional stage, but only two did when using ventilatory support. Transcutaneous carbon dioxide remained within normal range for all participants, on or off ventilatory support. Whilst some participants found testing challenging, participants generally reported both testing and air travel to be valuable. CONCLUSIONS: Evaluating response to patients' usual ventilation through "fitness-to-fly" assessment aids decision making when considering whether children who receive nocturnal ventilation can travel by air, since for some using a ventilator reduces or avoids the need for supplemental oxygen.

Congenital myasthenic syndromes: a retrospective natural history study of respiratory outcomes in a single centre.

Respiratory problems are a major cause of morbidity and mortality in patients with congenital myasthenic syndromes, a rare heterogeneous group of neuromuscular disorders caused by genetic defects impacting the structure and function of the neuromuscular junction. Recurrent, life-threatening episodic apnoea in early infancy and childhood and progressive respiratory failure requiring ventilation are features of certain genotypes of congenital myasthenic syndromes. Robb et al. published empirical guidance on respiratory management of the congenital myasthenic syndromes, but other than this workshop report, there are little published longitudinal natural history data on respiratory outcomes of these disorders. We report a retrospective, single-centre study on respiratory outcomes in a cohort of 40 well characterized genetically confirmed cases of congenital myasthenic syndromes, including 10 distinct subtypes (DOK7, COLQ, RAPSN, CHAT, CHRNA1, CHRNG, COL13A1, CHRNE, CHRNE fast channel syndrome and CHRNA1 slow channel syndrome), with many followed up over 20 years in our centre. A quantitative and longitudinal analysis of key spirometry and sleep study parameters, as well as a description of historical hospital admissions for respiratory decompensation, provides a snapshot of the respiratory trajectory of congenital myasthenic syndrome patients based on genotype.