Sarah Couldwell, a 52-year-old personal banker from Gosport, Hampshire, has lived with involuntary hand and arm tremors since adolescence, a condition she recently learned was essential tremor after a formal diagnosis in 2024. Essential tremor, the most common neurological movement disorder in the UK, affects approximately 600,000 people and is characterised by uncontrollable shaking that primarily impacts the hands and arms.
The condition, which often worsens with factors such as stress, caffeine intake, sleep deprivation, and aging, can make everyday activities like eating, typing, and handling small objects challenging. It tends to be more prevalent among individuals over 50 and slightly more common in men, though its exact causes remain unclear. Essential tremor can also run in families, as evidenced in Couldwell’s case, with an aunt known in her family for similar symptoms.
Current treatment options include medications such as propranolol and anti-seizure drugs like primidone and topiramate, which aim to suppress the overactive nerve signals believed to underlie the tremors. For more severe cases, surgical interventions such as deep brain stimulation (DBS) or MRI-guided ultrasound may be employed. DBS involves implanting electrodes targeting the ventral intermediate nucleus (VIM) in the brain to regulate abnormal signals, while MRI-guided ultrasound uses focused energy to ablate tissue in this area.
However, these surgical treatments are invasive and often require significant recovery time, limiting accessibility due to the availability of specialised centres and stringent patient criteria. Fewer than 200 patients annually in the UK receive these procedures despite the larger population affected.
A new approach, transcranial ultrasound stimulation (TUS), is currently being evaluated in a clinical trial at University College London Hospitals NHS Foundation Trust. Developed by NeuroHarmonics, a spin-out from University College London, TUS delivers low-intensity soundwaves through the skull to modulate brain activity without ablating tissue. The treatment can be conducted on awake patients in an outpatient setting, with a procedure lasting around 40 minutes. Patients wear a helmet that emits soundwaves targeted with MRI guidance at the VIM, while motion sensors monitor tremor severity in real-time.
Dr Bradley Treeby, co-founder of NeuroHarmonics and a lead figure in the trial, noted that TUS could offer a less invasive alternative for patients hesitant to undergo neurosurgery or who face barriers to accessing current surgical treatments. The technique is not expected to cause permanent brain lesions, and reported side effects are generally mild and transient.
Despite available treatments, many individuals with essential tremor do not seek medical advice until symptoms become significantly disabling. Consultant neurologist Dr Sharon Muzerengi highlighted that essential tremor can lead to social isolation and associated mental health challenges such as anxiety and depression.
Couldwell herself experienced side effects from various medications, leading her to discontinue treatment for the past year. The worsening tremors increasingly affected her daily work and personal life, making tasks such as handling money and eating difficult. Earlier this month, she underwent the initial phase of deep brain stimulation surgery and is scheduled to complete the implantation and activation process in the coming weeks. She expressed optimism that the procedure will markedly improve her quality of life.
The ongoing research into TUS offers potential for expanded treatment options for essential tremor sufferers, addressing both the invasiveness and accessibility challenges posed by current surgical methods.