Consultant oculoplastic surgeon Mr Daniel Ezra and Dr Michelle Ting look at some of the most common dystonias in the periocular area and advise on suitable treatment.
Involuntary eyelid twitching is a common presenting symptom to ophthalmologists. The differential diagnosis of periocular dystonias include eyelid myokymia, benign essential blepharospasm and hemifacial spasm. Each of these has a different cause, management and prognosis. In such patients, it is important to establish the correct diagnosis, rule out underlying pathology and provide a holistic approach to treatment. This range of conditions is of particular interest to aesthetic professionals who are likely to encounter such concerns as they treat the eye area with filler or botulinum toxin. It is important to note, however, that anyone performing these treatments must have the correct training and suitable knowledge of the anatomy and underlying disease. If they do not, I would recommend referring to a specialist.
Eyelid myokymia presents as gentle twitching of one eyelid, often described as a ‘fluttering’. It usually affects the lower lid, and typically occurs unilaterally. The movement is due to fasciculation of orbicularis oculi fibres.1 When both eyelids are involved, they twitch independently of each other. Contractions are self-limiting and episodic, lasting for a few seconds, but runs of these fasciculations can last for weeks or months. Myokymia can present at any age, although it is most frequently seen in adults. It is associated with fatigue, anxiety, stress, exercise and excessive use of caffeine.1 It is a benign condition, which tends not to be associated with other neurologic disease. The majority of cases resolve spontaneously; chronic cases respond well to treatment with botulinum toxin.2
Benign essential blepharospasm
Benign essential blepharospasm (BEB) is characterised by progressive bilateral involuntary spasms of the eyelid protractors (orbicularis oculi, corrugator, and procerus).5 It is a form of focal dystonia, which is defined as an involuntary prolonged contraction affecting a single body part or group of muscles. It has a prevalence of 5 to 13 per 100,000 people and is three times more common in females than males.3 BEB often involves the mid-face elevators and mouth or tongue. Neck involvement is also observed in severe cases.5
Presentation ranges from a mildly increased blink rate to forceful eyelid closure, which results in functional blindness.6 Photophobia, sensitivity or discomfort to light exposure occurs in approximately 80% of patients and often triggers eyelid spasms.4 Symptoms are also worse when patients are immersed in a moving visual field, for example while a passenger in a car. Symptoms may improve with concentration, physical tasks, talking, and are often ameliorated by downward gaze, shutting one eye or by applying focal pressure on the temple.5
BEB is a chronic and incurable condition. It typically progresses rapidly before becoming stable; remission is rare. It can be a disabling condition and may result in a limitation of activities as a part of daily living and reduced quality of life.7 Chronic BEB may lead to permanent anatomical sequelae, such as blepharoptosis, due to dehiscence of levator palpebrae superioris or entropion, because of the stretching of the lateral canthal tendon. Patients often overuse their frontalis to help ‘break’ spasmodic episodes, which may result in stretching and brow ptosis.8 The aetiology of BEB is thought to be multifactorial. The majority of cases are sporadic; however, approximately 20% have a positive family history of dystonia, suggesting a possible genetic aetiology.9 BEB may be a feature of other movement disorders such as Parkinson’s disease or Parkinsonian-plus syndromes, or tardive dystonia following neuroleptic treatment (commonly administered for psychiatric conditions). In keeping with this, neuropathological studies in BEB have shown abnormalities in the basal ganglia.10,11
The ocular surface disease plays an important role in the pathophysiology of BEB. In one study of 272 patients with blepharospasm, 57% had symptoms of ocular surface disease such as dryness, grittiness or irritation.12 It has been suggested that the increased blink rate initiated by dry eye becomes perpetuated and inappropriate as a result of induced trigeminal hypersensitivity.13 In my experience, BEB is frequently misdiagnosed as dry eye syndrome, resulting in delayed diagnosis.
Hemifacial spasm (HFS) is characterised by a unilateral involuntary, irregular, tonic contraction of the muscles innervated by the facial nerve. It can involve small parts of the face, or can be much more extensive, affecting the entire side of the face, including the platysmal neck muscles and brow.14 HFS usually presents between 40 and 50 years of age, with an average prevalence of 7.4 per 100,000 in men and 14.5 per 100,000 in women.14 Orbicularis oculi is the most common initial site before spreading to the lower face over months to years.14 In contrast to BEB, most cases of HFS are unilateral and the spasms may occur during sleep. The spasms may be associated with ipsilateral pain and are often exacerbated by coughing, fatigue or stress.
HFS is usually caused by the compression of the facial nerve root exit zone by an aberrant loop of the anterior inferior cerebellar, posterior inferior cerebellar, vertebral, or basilar artery.15 Other rarer causes of HFS include meningioma, schwannoma, parotid gland tumour, and pilocytic astrocytoma, causing facial nerve compression.16 All patients with HFS should be investigated with an MRI brain scan focusing on the facial nerve pathway to exclude a space-occupying lesion.
Clinical evaluation should include a thorough medical, drug and family history. Examination should involve an assessment of muscles affected, blink rate, and the presence of forced and prolonged eyelid closure. Assessing the muscle groups involved requires careful observation of the spasm and a detailed understanding of the function of the periocular musculature. It is also important to assess for occlusion positivity (improvement of symptoms with occlusion of either eye) and for relieving pressure points, which are typical in blepharospasm. Based on experience, I believe a complete cranial nerve exam should be performed, including testing of corneal sensation. A peripheral neurological exam must also be carried out to identify signs of Parkinsonism. An ophthalmic examination with slit-lamp biomicroscopy is also essential to identify blepharitis and dry eye.5 These examinations are usually carried out by doctors specialising in neurology or ophthalmology so would need to be referred on.
When dealing with BEB or HFS, which are more severe than myokymia, the effect of the condition on the patient’s quality of life can be objectively assessed using various quality of life scales. The Blepharospasm Disability Scale (BDS) is an effective measure that can be completed quickly with minimal instruction.17
Each condition has a different treatment approach, but will usually involve the administration of botulinum neurotoxin (BoNT). Myokymia rarely requires treatment, but if bothersome, low-dose toxin injections (approximately 0.5-1 units/0.1ml for Botox and Xeomin, or 10-20 units/0.1ml for Dysport, for example) can be given directly to the affected areas with symmetrising doses to the contralateral side.
Patients with HFS also respond well to treatment with BoNT injections.18 Injections need to be administered carefully to control the affected muscles, with great care taken to ensure that the ipsilateral antagonist muscles and contralateral corresponding muscles are also treated where necessary to maintain facial symmetry. The location and dosing of these injections is completely bespoke for each patient.
The most common muscle groups injected are frontalis, orbicularis oculi, corrugators, zygomaticus major, medial mid-face and lip elevators (levator labii superioris at alaeque nasi, platysma and depressor anguli oris). The clinical decision for treatment is based on very careful observation of affected muscle groups, as well as patient expectations. Sometimes neurosurgical referral for microvascular decompression of the facial nerve can be considered, and this is curative in up to 90% of cases.19
When managing patients with BEB, more of a holistic approach is required. Patient education and supportive care are fundamental. Support groups such as the Benign Essential Blepharospasm Research Foundation (BEBRF) and the Dystonia Society in the United Kingdom can be recommended to give patients support.29,30 In one study of 1,653 patients, 90% of patients felt that the support groups had provided them with considerable assistance.4
Ophthalmic management of the afferent blink reflex pathway is also vital. Treatment of dry eye should be addressed with the use of lubricants (for example hypromellose, carmellose or sodium hyaluronate eye drops) and treatment of blepharitis with hot compresses or short-term topical steroids.32
Patients with BEB tolerate a lower intensity of light than normal subjects. Some patients may benefit from wearing lenses such as FL-41 tints (glasses with therapeutic tinted lenses) or from the use of Bangerter occlusion foils (translucent plastic filters which block light transmission that reduce visual activity).20
However, the mainstay of treatment of BEB is BoNT. The American Academy of Ophthalmology collected data on 4,340 patients with blepharospasm treated with BoNT, and found that 90% clinically improved.21 BoNT is injected subcutaneously into four to five sites around the orbicularis oculi muscle. Adverse effects include bruising, ptosis, dry eye, entropion (in-turning of the lower lid), ectropion (out-turning of the lower lid), and excessive tearing. These are usually short-lived in relation to the period of therapeutic benefit.22 To prevent ptosis, one should avoid injecting around the central preseptal part of the upper orbicularis oculi. Numerous studies have shown the benefit of injecting BoNT into the pretarsal rather than the preseptal portion of the orbicularis.29-31
Pretarsal injections appear to improve response when pretarsal spasm is present, although they tend to be more painful and have a higher incidence of bruising.23 Other muscles such as the procerus, corrugators and mid-face elevators are also often injected.
Planning BoNT therapy in BEB is highly complex and requires a detailed assessment of the affected muscles. It is given in low to standard doses (for example, 1.25-5 of Xeomin or Botox and 5-20 units of Dysport per injection site) with early review of its effects. Initial effect is generally seen within three days and reaches a peak one to two weeks’ post treatment. The optimal dose is the least amount of BoNT necessary to achieve the desired outcome without adverse effects.
The duration of the BoNT treatment is approximately three months for all of these conditions, after which repeat injections may be given if required. Intervals between injections of less than nine weeks and booster injections two weeks after the initial injection should be avoided as they may predispose to biological resistance.24 Long-term loss of effectiveness of the treatment is rare, and is thought to be due to the formation of neutralising antibodies.25
Systemic treatments are an important treatment modality when patients with BEB are unresponsive to BoNT injections. Improvements have been demonstrated in small numbers of patients taking a range of drugs, including haloperidol, l-dopa and deprenyl, trihexyphenidyl, and clonazepam. However, there appears to be no consistent or predictably effective systemic drug treatment available.26
Surgery can be of benefit in patients with BEB who are refractory to medical therapies. Constant and forced closure of the eyes can cause brow descent and excess upper lid skin. The mechanical compaction can be relieved with surgical correction such as brow lifting, blepharoplasty or ptosis repair, which can be extremely effective. In addition, the frontalis sling operation is highly effective in patients with apraxia of eyelid opening.27 It is important to warn patients that surgery is not usually curative and continued treatment with BoNT injections is necessary alongside this.
Although eyelid twitching may seem an innocuous symptom, it represents a variety of possible conditions, each with different aetiopathologies and treatments. Unresolved periocular spasms should always be referred to a specialist for evaluation. The diagnosis of myokymia, blepharospasm and hemifacial spasm can be easily confused. In some patients, ongoing symptoms may represent serious underlying pathology, which will require specialist multidisciplinary management. Therefore, if symptoms persist then referral to an ophthalmologist or neurologist is essential.
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