Quantitative Foot Muscle Magnetic Resonance Imaging Reliably Measures Disease Progression in Children and Adolescents with Charcot-Marie-Tooth Disease Type 1A.

Quantitative muscle fat fraction (FF) responsiveness is lower in younger Charcot-Marie-Tooth disease type 1A (CMT1A) patients with lower baseline calf-level FF. We investigated the practicality, validity, and responsiveness of foot-level FF in this cohort involving 22 CMT1A patients and 14 controls. The mean baseline foot-level FF was 25.9 ± 20.3% in CMT1A patients, and the 365-day FF (n = 15) increased by 2.0 ± 2.4% (p < 0.001 vs controls). Intrinsic foot-level FF demonstrated large responsiveness (12-month standardized response mean (SRM) of 0.86) and correlated with the CMT examination score (ρ = 0.58, P = 0.01). Intrinsic foot-level FF has the potential to be used as a biomarker in future clinical trials involving younger CMT1A patients. ANN NEUROL 2024;96:170-174.

Quantitative MRI outcome measures in CMT1A using automated lower limb muscle segmentation.

BACKGROUND: Lower limb muscle magnetic resonance imaging (MRI) obtained fat fraction (FF) can detect disease progression in patients with Charcot-Marie-Tooth disease 1A (CMT1A). However, analysis is time-consuming and requires manual segmentation of lower limb muscles. We aimed to assess the responsiveness, efficiency and accuracy of acquiring FF MRI using an artificial intelligence-enabled automated segmentation technique. METHODS: We recruited 20 CMT1A patients and 7 controls for assessment at baseline and 12 months. The three-point-Dixon fat water separation technique was used to determine thigh-level and calf-level muscle FF at a single slice using regions of interest defined using Musclesense, a trained artificial neural network for lower limb muscle image segmentation. A quality control (QC) check and correction of the automated segmentations was undertaken by a trained observer. RESULTS: The QC check took on average 30 seconds per slice to complete. Using QC checked segmentations, the mean calf-level FF increased significantly in CMT1A patients from baseline over an average follow-up of 12.5 months (1.15%±1.77%, paired t-test p=0.016). Standardised response mean (SRM) in patients was 0.65. Without QC checks, the mean FF change between baseline and follow-up, at 1.15%±1.68% (paired t-test p=0.01), was almost identical to that seen in the corrected data, with a similar overall SRM at 0.69. CONCLUSIONS: Using automated image segmentation for the first time in a longitudinal study in CMT, we have demonstrated that calf FF has similar responsiveness to previously published data, is efficient with minimal time needed for QC checks and is accurate with minimal corrections needed.

Neurology and the histiocytoses: a case of Rosai-Dorfman-Destombes disease.

The histiocytoses are a group of rare disorders characterised by the accumulation of neoplastic or non-neoplastic activated histiocytes in various tissues. Phenotypes vary widely from cutaneous lesions or lymphadenopathy that regress spontaneously to disseminated disease with poor prognosis. Neurological symptoms can be a presenting feature or appear during the course of disease. We present a challenging diagnostic and management case of Rosai-Dorfman-Destombes disease in a 48-year-old woman with a relapsing, partially steroid-responsive syndrome comprising patchy, non-length-dependent radiculoneuropathy with diffuse pachymeningitis and widespread systemic disease, and recent dramatic response to novel mitogen-activated kinase pathway inhibition. We discuss the clinical characteristics, diagnosis, recent breakthroughs in pathogenesis and emerging treatment options for Rosai-Dorfman disease and for the histiocytoses with neurological sequelae, including Langerhans cell histiocytosis and Erdheim-Chester disease.

Use of Twitter in Neurology: Boon or Bane?

Twitter is a free, open access social media platform that is widely used in medicine by physicians, scientists, and patients. It provides an opportunity for advocacy, education, and collaboration. However, it is likely not utilized to its full advantage by many disciplines in medicine, and pitfalls exist in its use. In particular, there has not been a review of Twitter use and its applications in the field of neurology. This review seeks to provide an understanding of the current use of Twitter in the field of neurology to assist neurologists in engaging with this potentially powerful application to support their work.

An unusual cause of hemifacial spasm.

Hemifacial spasm is not an infrequent presentation and a vascular loop is commonly implicated. Cerebellopontine angle (CPA) lesions are uncommon but can be excluded with appropriate imaging. There have been only around 150 case reports of CPA lipoma; hemifacial spasm has been associated only in eight cases. We present an additional case and discuss the literature and management.

'Scan-negative' cauda equina syndrome: Evidence of functional disorder from a prospective case series.

In the first prospective comparison of 'scan-negative' (n=11) and 'scan-positive' (n=7) patients with cauda equina syndrome (CES) we found that Hoover's sign of functional leg weakness but not routine clinical features differentiated the two groups (p<0.02). This offers a new direction of study in this area, although magnetic resonance imaging is still required for all patients with possible CES.

Lower limb muscle MRI fat fraction is a responsive outcome measure in CMT X1, 1B and 2A.

OBJECTIVE: With potential therapies for many forms of Charcot-Marie-Tooth disease (CMT), responsive outcome measures are urgently needed for clinical trials. Quantitative lower limb MRI demonstrated progressive calf intramuscular fat accumulation in the commonest form, CMT1A with large responsiveness. In this study, we evaluated the responsiveness and validity in the three other common forms, due to variants in GJB1 (CMTX1), MPZ (CMT1B) and MFN2 (CMT2A). METHODS: 22 CMTX1, 21 CMT1B and 21 CMT2A patients and matched controls were assessed at a 1-year interval. Intramuscular fat fraction (FF) was evaluated using three-point Dixon MRI at thigh and calf level along with clinical measures including CMT examination score, clinical strength assessment, CMT-HI and plasma neurofilament light chain. RESULTS: All patient groups had elevated muscle fat fraction at thigh and calf levels, with highest thigh FF and atrophy in CMT2A. There was moderate correlation between calf muscle FF and clinical measures (CMTESv2 rho = 0.405; p = 0.001, ankle MRC strength rho = -0.481; p < 0.001). Significant annualised progression in calf muscle FF was seen in all patient groups (CMTX1 2.0 ± 2.0%, p < 0.001, CMT1B 1.6 ± 2.1% p = 0.004 and CMT2A 1.6 ± 2.1% p = 0.002). Greatest increase was seen in patients with 10-70% FF at baseline (calf 2.7 ± 2.3%, p < 0.0001 and thigh 1.7 ± 2.1%, p = 0.01). INTERPRETATION: Our results confirm that calf muscle FF is highly responsive over 12 months in three additional common forms of CMT which together with CMT1A account for 90% of genetically confirmed cases. Calf muscle MRI FF should be a valuable outcome measure in upcoming CMT clinical trials.

Diagnostic Lumbar Puncture.

Diagnostic Lumbar Puncture is one of the most commonly performed invasive tests in clinical medicine. Evaluation of an acute headache and investigation of inflammatory or infectious disease of the nervous system are the most common indications. Serious complications are rare, and correct technique will minimise diagnostic error and maximise patient comfort. We review the technique of diagnostic Lumbar Puncture including anatomy, needle selection, needle insertion, measurement of opening pressure, Cerebrospinal Fluid (CSF) specimen handling and after care. We also make some quality improvement suggestions for those designing services incorporating diagnostic Lumbar Puncture.