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Association of the Achondroplasia Foramen Magnum Score and intraoperative neuromonitoring
  1. Claudia Craven1,
  2. Ivana Jankovic2,
  3. Edward Dyson3,
  4. Stewart G Boyd2,
  5. Felice D'Arco4,
  6. Moira Shang-Mei Cheung5,
  7. Dominic Thompson6
  1. 1Neurosurgery, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
  2. 2Department of Clinical Neurophysiology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
  3. 3Department of Neurosurgery, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
  4. 4Paediatric Neuroradiology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
  5. 5Department of Paediatric Endocrinology, Evelina London Children's Hospital, London, UK
  6. 6Department of Paediatric Neurosurgery, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
  1. Correspondence to Dr Claudia Craven, Neurosurgery, Cambridge University Hospitals NHS Foundation Trust, Cambridge, CB2 0QQ, UK; claudia.craven{at}gmail.com

Abstract

Introduction Foramen magnum stenosis in achondroplasia carries a risk of sudden death. A proportion of these patients benefit from foramen magnum decompression (FMD). The Achondroplasia Foramen Magnum Score (AFMS) was developed to stratify those most at risk. We hypothesise that this score may be reflected in neurophysiological findings.

Methods Patients with achondroplasia who had undergone FMD (n=20) were retrospectively grouped into AFMS 2, 3 and 4. Amplitude from tibialis anterior (TA) and the percentage change in somatosensory evoked potential (SSEP) latency after FMD were reported.

Results Baseline motor evoked potential amplitudes for patients with AFMS=4 were significantly lower left (p=0.0017 and p=0.02 for right and left TA, respectively) compared with AFMS grades 2 and 3. Median reduction (% change) in SSEP latency (ms) after surgery was not significantly different in any of the patients.

Conclusions This short report cross-references AFMS to intraoperative neuromonitoring. Baseline amplitudes were noticeably lower in the most severe AFMS group. This observation supports the notion that AFMS can help risk stratify patients and aid in surgical selection.

  • Neurosurgery
  • Neurology
  • Paediatrics
  • Physiology

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Footnotes

  • X @Great Ormond Street Neurosurgery@GOSH_Neurosurg

  • Contributors CC wrote and edited the manuscript. DT and MS-MC conceived the idea and collected the clinical data. IJ and SGB performed the intraoperative neuromonitoring. FD'A performed the imaging and reporting. ED assisted in data capture and provided the imaging for the manuscript. DT, MS-MC, IJ, SGB and FD'A provided senior input and guidance throughout. CC is guarantor.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.