The 20th Annual King’s Neuromuscular symposium, held online for the second consecutive year, hosted speakers from Australia, UK, Netherlands, France, and the USA. The meeting provides practical clinical updates and interesting cases for healthcare professionals who look after patients with neuromuscular diseases. This was our third attendance and, as previously, we left with useful tips that we have used almost immediately afterwards.
The symposium started at 9am GMT (8pm Sydney time) with Professor Matthew Kiernan delivering a fascinating talk on nerve excitability studies. Neurophysiology training in the UK does not typically include threshold tracking so it was interesting to discover how this technique has improved our understanding of uraemic and chemotherapy-induced neuropathies, its role in monitoring response to treatments, and how it may detect abnormalities earlier than nerve conduction studies. It must indeed be an excellent talk when Richard Hughes writes, “excellent talk” in the chat of the Richard Hughes lecture!
Our in-house peripheral nerve expert, Dr Rob Hadden (Consultant Neurologist, King’s College Hospital, UK) delivered the second talk. He gave a clear explanation of the recently updated (2021) CIDP guidelines, which he co-authored. The guidelines now include helpful flowcharts for navigating this complicated disease. He made three important points: CIDP remains a diagnostic challenge, refractory CIDP may be the wrong diagnosis (test those nodal/paranodal antibodies!) and CIDP variants are the most likely to be mis-diagnosed. The guidelines provide important red flags, centred around these variant forms. Guillain-Barré syndrome guidelines are also in the pipeline and a CIDP guidelines phone app is under development.
We stayed on the CIDP theme, but headed to the Netherlands for a talk by Dr Franssen with practical tips on interpreting nerve conduction studies in CIDP. He nicely described the key terms (including CMAP drop, conduction block, temporal dispersion) and the origins of cut-off values for velocity and amplitude or area changes dating back to the late 1970s. He finished with 6 practical hints emphasising the importance of limb temperature, stimulator position, assessing the shape of the CMAP not just its amplitude, and interpreting with caution when CMAPs are small (<1mV).
Dr Paul Seror, Consultant Rheumatologist from Université Paris VI, France, gave an in-depth and highly practical talk on neuromuscular disorders affecting the scapula, of interest to a diverse multi-disciplinary audience. He showed us a systematic approach to clinical examination and electrophysiology of the muscles that control the scapula, including video analysis of the scapular rhythm during upper limb circumduction. Video analysis is something we may incorporate into our own clinics as the ability to pause and replay can be extremely helpful. A thorough electrodiagnostic study further improves the diagnosis.
If, like us, you rarely come across mitochondrial diseases then Dr Pitceathly’s talk from University College London, UK, would have been ideal for you. There have been rapid developments in this field, which he managed to cover along with the common presentations and the basics of mitochondrial genetics. It was fantastic to hear that at Queen Square the 100K genomes project resulted in new genetic diagnoses in 30% of patients. There are, however, many ongoing diagnostic challenges including heteroplasmy, complex family histories and phenocopies.
Professor Charles Thornton from Rochester, USA, gave us an excellent update on the clinical and pathological features of myotonic dystrophy, including some very helpful videos of myotonia. He reminded us that myotonic dystrophy is a heterogeneous disorder with many unanswered questions and considerable scope for research. Nevertheless, he shared exciting developments in treatment of this disease. The first pre-clinical trial of an antisense oligonucleotide in a mouse model of myotonic dystrophy is underway, and preliminary data suggest that both the clinical myotonia and RNA toxicity are improved.
Finally, Professor Roy Freeman treated us to a very informative and entertaining talk about some of the many faces of autonomic neuropathy. He navigated the complex topic of autonomic neuropathies and provided useful tips on how to approach these disorders. We mention here two of the important points he made. When suspecting an autonomic neuropathy, nicotinic acetylcholine receptor should always be requested because autoimmune autonomic ganglionopathy is treatable. Treatment-related neuropathy, should be suspected in diabetic patients who develop acute severe pain and dysautonomia after rapid correction of blood glucose. The hallmark of this condition is a rapidly declining HbA1c.
Key learning points:
- Nerve excitability studies detect abnormalities earlier than nerve conduction studies in some neuropathies such as uraemic and oxaliplatin induced neuropathies.
- New chronic inflammatory demyelinating polyneuropathy (CIDP) guidelines simplify this complex diagnosis.
- In CIDP interpreting nerve conduction slowing and amplitude drops requires careful attention to limb temperature, stimulator position, CMAP duration and CMAP area.
- In scapular winging, both video and electrophysiology contribute to accurate diagnosis.
- Whole genome sequencing has resulted in a new diagnosis in 30% of patients with previously undiagnosed mitochondrial disorders.
- Gene therapy is promising in the management of myotonic dystrophy.
- There are important treatable and reversible causes of autonomic neuropathy.