Introduction

William's syndrome, also written Williams syndrome and sometimes called Williams-Beuren syndrome, is a genetic condition caused by the deletion of a small segment of chromosome 7. The missing region contains roughly 25 to 28 genes, including the gene for elastin, a protein that gives blood vessels and other tissues their elasticity. The condition affects many body systems at once, so people with William's syndrome often see several different specialists over the course of their lives.

Among the many symptoms that families report, dizziness and unsteadiness are common and often under-recognised. Dizziness in William's syndrome rarely has a single cause. It usually emerges from a combination of inner-ear function, blood vessel and blood pressure behaviour, sound sensitivity, neurological differences and anxiety. Understanding each of these contributors makes the problem easier to investigate and easier to treat.

What is William's syndrome?

William's syndrome occurs in roughly one in every 7,500 to 10,000 births and is usually not inherited; the chromosome deletion typically happens spontaneously. The classic features include:

• A distinctive facial appearance, with a broad forehead, periorbital fullness, a short upturned nose and a wide mouth.
• Cardiovascular problems, most commonly supravalvular aortic stenosis, along with narrowing of other arteries.
• Mild to moderate intellectual disability, with relative strengths in verbal language and face recognition, and relative weaknesses in visuospatial construction.
• A strikingly outgoing, friendly and empathetic personality profile.
• Connective tissue differences affecting joints, skin and the gastrointestinal tract.
• Heightened sensitivity to sound, known as hyperacusis, and other sensory sensitivities.
• An increased risk of hypertension, hypercalcaemia in infancy, and kidney or urinary tract differences.

Because the elastin gene is part of the deleted region, blood vessel walls are often stiffer and narrower than usual, and this has consequences for circulation, blood pressure and the way the body responds to changes in posture and exertion.

Why dizziness occurs in William's syndrome

When a person with William's syndrome reports dizziness, the description of the symptom matters a great deal. Lightheadedness on standing, a spinning sensation, a sense of floating, unsteadiness while walking, and a feeling of being overwhelmed by sound are different experiences that point to different mechanisms. Several of the following contributors may be present at the same time.

Cardiovascular factors

Narrowing of the aorta or of the arteries supplying the brain can reduce the body's ability to regulate blood flow during activity, and can produce lightheadedness, exercise intolerance or fainting. Hypertension is also more common in William's syndrome than in the general population, and both high and fluctuating blood pressure can cause dizziness. Orthostatic intolerance, in which blood pressure falls or the heart rate rises excessively on standing, is another frequent finding; people who become lightheaded within seconds to minutes of standing up should be assessed for this specifically.

Vestibular and balance function

Studies of balance in William's syndrome have found that many individuals perform below age expectations on tests of postural stability, and that balance difficulties persist beyond childhood. Some of this reflects differences in the vestibular system, the inner-ear apparatus that detects head movement and gravity. Some of it reflects differences in the cerebellum, the brain region that integrates balance information, and some reflects altered processing of sensory input from joints, muscles and vision. Structural differences in the vestibular apparatus of the inner ear have been described in some individuals. A degree of vestibular dysfunction may therefore coexist with cardiovascular and sensory factors, which is why a full balance assessment is worthwhile rather than assuming a single diagnosis.

Middle-ear and hearing conditions

Recurrent middle-ear infections and eustachian tube dysfunction are common in young children with William's syndrome, and chronic fluid behind the eardrum can cause unsteadiness as well as muffled hearing. Hearing loss, whether conductive, sensorineural or mixed, may also contribute to a sense of imbalance and to difficulty orienting in space.

Hyperacusis and sound-related dizziness

Hyperacusis, an abnormally strong sensitivity to everyday sounds that most people find comfortable, affects a large proportion of people with William's syndrome. It is not simply dislike of loud noise; the auditory system appears to amplify or over-react to ordinary sound, and this can trigger a startle response, a spike in anxiety, a rise in heart rate and a feeling of dizziness or disorientation. Some individuals describe the sensation as the room tilting or as a sudden sensation of motion in response to a sharp sound.

Hyperacusis also interacts with balance in a practical way. A person who is already unsteady may respond to an unexpected noise by tensing, turning quickly or adapting their posture abruptly, which in turn provokes dizziness. This overlap explains why sound sensitivity and balance complaints so often appear together in William's syndrome, and why both need to be addressed rather than treating either one alone.

Anxiety and sensory overload

Anxiety is common in William's syndrome and is not merely a reaction to frequent medical appointments. Heightened arousal increases awareness of heartbeat, breathing and bodily sensations, and can amplify a mild sensation of unsteadiness into a disabling one. Busy environments, noisy rooms and situations involving novelty or social pressure frequently trigger both anxiety and dizziness in combination. Recognising this pattern is important, because a person whose dizziness has a strong anxiety component still has a genuine symptom and still benefits from treatment.

Other contributors

Additional factors that can cause or worsen dizziness include dehydration, anaemia, thyroid disease, medication side effects, sleep deprivation, low blood sugar and, rarely in this population, structural abnormalities at the base of the skull. Migraine, which is more common in some people with William's syndrome, can also present with dizziness as a prominent feature.

How dizziness is evaluated

Assessment usually begins with a careful history. Useful details include what the sensation feels like, how long it lasts, what brings it on, whether it happens on standing or with movement, whether sound triggers it, whether hearing has changed, and what medications are being taken.

A thorough evaluation may include:

• Blood pressure measurement while lying, sitting and standing, including heart rate at each position.
• Cardiac assessment, since narrowing of the aorta and other vessels can be silent until symptoms appear.
• Audiological testing, including pure-tone thresholds and assessment of sound tolerance, to characterise hearing loss and hyperacusis.
• Vestibular testing, such as videonystagmography, vestibular evoked myogenic potentials or rotational testing, to identify inner-ear dysfunction.
• Balance and gait assessment, often with physiotherapy input.
• Blood tests to exclude anaemia, thyroid dysfunction, electrolyte problems and other reversible causes.
• Imaging when the history or examination suggests a structural cause.

Because William's syndrome affects multiple systems, the most useful approach is coordinated rather than piecemeal. A team that includes a paediatrician or internist, a cardiologist, an audiologist, a physiotherapist with balance experience and a mental health professional can address the different threads of the problem at once.

Management approaches

Addressing the cardiovascular contribution

Blood pressure should be monitored regularly, including measurements taken in different positions. Where orthostatic intolerance is identified, increased fluid and salt intake, compression garments, slow position changes and, in some cases, medication can help. Significant arterial narrowing may require cardiology follow-up.

Vestibular rehabilitation

Vestibular rehabilitation is a structured programme of exercises designed to reduce dizziness, improve gaze stability and retrain balance. It is often the single most useful intervention for persistent dizziness, and it can be adapted for people with intellectual disability by simplifying instructions, using demonstration and involving caregivers in practice sessions.

Managing hyperacusis

Sound sensitivity is best managed gradually and patiently. Strategies that are frequently helpful include:

• Identifying the specific sounds that are most troublesome and the situations in which they occur.
• Using ear protection selectively rather than constantly, since over-protection can increase sensitivity over time.
• Gradual, controlled exposure to tolerated sounds at low volume, ideally guided by an audiologist.
• Warning and preparation before unavoidable loud events, and the option to leave or take a break.
• Environmental adjustments such as soft furnishings, quieter rooms and predictable routines.
• Relaxation and breathing techniques that can interrupt the startle-and-anxiety cycle.

Addressing anxiety and sensory load

Cognitive behavioural approaches, adapted to the individual's level of understanding, can reduce the fear that develops around dizziness and noise. Reducing overall sensory load through predictable schedules, quiet spaces and adequate rest helps both the anxiety and the dizziness. Where anxiety is severe, medication may be considered by the treating clinician.

General measures

Staying well hydrated, eating regular meals, maintaining a consistent sleep schedule, avoiding excessive caffeine and reviewing medications that can cause dizziness are simple steps that often produce meaningful improvement. Physiotherapy for strength, gait and confidence in walking is valuable for people whose unsteadiness has led to reduced activity.

When to seek urgent medical attention

Dizziness is usually manageable, but some accompanying features require prompt assessment:

• Fainting or loss of consciousness.
• Chest pain, breathlessness or a marked change in exercise tolerance.
• Sudden hearing loss or a sudden change in hearing in one ear.
• Severe or unusual headache, weakness, numbness, slurred speech, or difficulty walking that has appeared suddenly.
• Persistent vomiting, palpitations or a very fast or very slow heart rate.

Summary

In William's syndrome, dizziness is rarely a single-disease problem. Cardiovascular narrowing and blood pressure instability, inner-ear and balance differences, middle-ear disease, hyperacusis, sensory overload and anxiety all interact, and any one of them can dominate at a given time. The most effective approach is to describe symptoms precisely, evaluate each plausible contributor, and combine medical management with vestibular rehabilitation, sound-desensitisation work and support for anxiety. With this kind of coordinated care, most people with William's syndrome can reduce the frequency and severity of their dizzy episodes and regain confidence in daily activity.