SHORT SUMMARY
Introduction: This thesis explores hyperkinetic movement disorders across various neurological conditions and investigates their treatment approaches. While not typically associated with motor neuron disease (MND), hyperkinetic movements are frequently observed in MND patients. In spinal muscular atrophy (SMA), hyperkinetic movements are recognized, but their mechanisms remain unclear. Nusinersen, a treatment for SMA, has demonstrated improvements in motor function, even in adult SMA patients. Primidone and propranolol are first line treatments for essential tremor (ET), although their mechanisms of action are not fully understood. Task-specific dystonia (TSFD) has limited treatment options, with zolpidem showing some promise; however, its effectiveness and mechanisms of action remain insufficiently studied.
Aims: (1) Investigate hyperkinetic movements in MND, (2) assess hyperkinetic movements in SMA and the impact of nusinersen on these movements, (3) explore the mechanisms of primidone and propranolol in ET, (4) evaluate zolpidem's effectiveness in TSFD and its underlying mechanisms.
Methods: Four patient cohorts were studied: 77 MND patients, 37 SMA patients initiating nusinersen, 54 ET patients starting primidone or propranolol, and 24 TSFD patients. Involuntary movements in MND and SMA were assessed using accelerometry, electromyography, and clinical evaluation, with reassessment in SMA patients after nusinersen treatment. Corticospinal and intracortical excitability were studied using transcranial magnetic stimulation (TMS) in ET and TSFD patients to explore treatment effects.
Results: (1) Involuntary movements were observed in 68.9% of MND patients and were linked to muscle weakness. (2) Nusinersen reduced involuntary movements’ amplitude in all patients and reduced muscle fatigue in SMA type 2. (3) Primidone reduced tremor by reducing corticospinal excitability and modulating GABA circuits. Propranolol acted centrally through GABA outflow modulation. (4) Zolpidem improved TSFD by reducing corticomotor output and altering brain metabolism.
Conclusions: This thesis characterizes hyperkinetic movements in MND and SMA, highlights nusinersen’s benefits, and elucidates the mechanisms of primidone, propranolol, and zolpidem in ET and TSFD.
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