Spasmodic dysphonia (laryngeal dystonia): symptoms, diagnosis and treatment

University College London Hospitals NHS Foundation Trust (UCLH) explains that laryngeal dystonia, also known as spasmodic dysphonia, is caused by abnormal activity in the brain that makes the voice box muscles go into spasm when a person speaks. The unwanted spasm causes the voice and speech problem. Dystonia UK adds that dystonia is caused by incorrect signals from the brain to the affected body part, and that the reasons are not yet fully understood.

Most laryngeal dystonia is focal, meaning it affects only one part of the body, though Dystonia UK says in some people dystonia may eventually involve other areas such as the eyes, jaw or neck. Stress and anxiety are known to make symptoms worse, but they are not the cause of the condition.

Dystonia UK describes three patterns. In adductor laryngeal dystonia, the most common type, the vocal cords are pulled together during speech, which gives the voice a strangled quality. In abductor laryngeal dystonia the vocal cords are pulled apart, making the voice breathy and very quiet. Adductor breathing laryngeal dystonia is rarer: the cords are pulled together during breathing, which leads to noisy and laboured breathing and sometimes trouble swallowing.

• A strangled-sounding voice and/or a feeling of choking on words.

• Effortful speech.

• A breathy, quiet voice that is difficult to project.

• Voice tremor.

• Symptoms that are worse with stress or anxiety.

Dystonia UK says the causes are not yet fully understood. There is some research into whether genetic factors play a part, and some cases are thought to be triggered by trauma such as intubation or neck injuries. Symptoms usually appear between the ages of 40 and 50, and laryngeal dystonia may also occur in cases of childhood-onset generalised dystonia, which affects multiple body parts including the limbs.

It is useful to know what it is not. It is a neurological movement disorder rather than a problem with the vocal cords themselves, so a persistent hoarse or strained voice that does not improve should be assessed by a specialist rather than treated as a simple throat infection or put down to overuse.

Dystonia UK says laryngeal dystonia should be diagnosed and treated by an ENT specialist or a neurologist specialising in movement disorders. The sources used here do not describe the clinic assessment step by step, but UCLH's mention of EMG-guided injection and of speech and language therapy shows that ENT, neurology and voice therapy teams are all involved.

UCLH says that before deep brain stimulation, patients have detailed brain MRI scans, voice recordings and pre-operative assessments.

UCLH states that at present there is no cure for laryngeal dystonia, and sets out the options. Dystonia UK lists the common treatments as botulinum toxin injections, oral medication, speech and language therapy and surgical procedures.

UCLH says deep brain stimulation (DBS) delivers a high-frequency electrical current to an area of the brain called the thalamus and does not cure the disorder but aims to help control symptoms. It describes DBS as an established treatment for generalised and focal dystonia, but says treating patients solely for laryngeal dystonia is new at its Trust, and that it expects all patients to have tried botulinum toxin and to have had speech and language therapy first.

Surgery takes 2 to 3 hours, with a hospital stay of 4 to 5 days, and programming of the stimulator starts 2 to 4 weeks later, taking 2 to 6 months to reach the right settings. UCLH lists reasons DBS may not be suitable, including significant cognitive decline, swallowing problems, severe depression and a history of falls or balance problems. It gives risks such as bleeding in the brain in less than 1% (less than 1 in 100) and infection in fewer than 2 in 100 patients.

Dystonia UK says you may need to find ways to adapt, that it is possible to live well with the condition and that the charity supports people from onset to diagnosis and treatment. Techniques it lists as helpful include vocal exercises such as humming, speaking slowly or reciting nursery rhymes, volume control, relaxation techniques, deeper breathing and exhaling before speaking, controlling the environment by talking one-to-one without interruption, using the voice early in the morning, sensory gestures such as covering the eyes or pinching the nose, physical exercise (after checking with a doctor), and vocal rest and warm liquids.

A speech and language therapist, who UCLH says is involved in care before and after any surgery, is the professional best placed to help you apply these techniques to everyday situations.

On the NHS, the route is usually via the GP to ENT or a voice clinic, then to a specialist service for botulinum toxin injections and, for a few people, referral to a neurosurgical centre for DBS. UCLH notes that people not suitable for DBS are referred back to the ENT consultant to discuss alternatives.

Some people also see private ENT or voice specialists for faster assessment or injections. The treatments are the same, and because injections need to be repeated every few months, ask who will provide ongoing treatment, how to book repeat injections and what the cost or commissioning arrangements are.