Electromyography and recovery of the blink reflex in involuntary eyelid closure: a comparative study.

Electromyographic (EMG) activity of orbicularis oculi and levator palpebrae muscles was recorded to study the origin of involuntary eyelid closure in 33 patients. The evoked blink reflex in all patients and in 23 controls was also studied. To examine the excitability of facial motoneurons and bulbar interneurons in individual patients and to compare the results with EMG findings, R1 and R2 recovery indices were calculated in all subjects, as the average of recovery values at 0.5, 0.3, and 0.21 second interstimulus intervals. Based on EMG patterns, the patients were divided into three subclasses: EMG subclass 1, 10 patients with involuntary discharges solely in orbicularis oculi muscle; EMG subclass 2, 20 patients with involuntary discharges in orbicularis oculi and either involuntary levator palpebrae inhibition or a disturbed reciprocal innervation between orbicularis oculi and levator palpebrae; EMG subclass 3, three patients who did not have blepharospasm, but had involuntary levator palpebrae inhibition in association with a basal ganglia disease. The total patient group showed an enhanced recovery of both R1 and R2 components compared with controls. Although 30 out of 33 patients had blepharospasm (EMG subclasses 1 and 2), R1 recovery index was normal in 64% and R2 recovery index was normal in 54%. Patients with an abnormal R2 recovery index had an abnormal R1 recovery index significantly more often. All patients from EMG subclass 1 had an abnormal R2 recovery index, whereas all patients from EMG subclass 3 had normal recovery indices for both R1 and R2 responses. Seventy five per cent of the patients from EMG subclass 2 had normal recovery indices. The results provide further evidence that physiologically blepharospasm is not a homogeneous disease entity, and indicate that different pathophysiological mechanisms at the suprasegmental, or segmental level, or both are involved.     

Shortened cortical silent period in facial muscles of patients with cranial dystonia

OBJECTIVE: To study the cortical silent period (SP) in the orbicularis oculi and perioral muscles in 23 patients with cranial dystonia and 10 age-matched control subjects. METHODS: High-intensity magnetic stimuli were delivered with a round coil centered at the vertex during a maximal muscle contraction. Electromyographic (EMG) responses were recorded from surface electrodes placed over the orbicularis oculi and perioral muscles. RESULTS: SPs elicited in upper and lower facial muscles had a similar duration. Facial muscle SPs were significantly shorter in patients than in control subjects. Patients with blepharospasm plus oromandibular dystonia had shorter SPs than patients with blepharospasm alone. Although patients' recordings showed reduced voluntary and evoked EMG activity, neither activities correlated with the duration of the SP. CONCLUSIONS: Silent period (SP) shortening depends neither on the level of electromyographic activity nor on segmentary mechanisms. The shortened SP in facial muscles reflects hypoexcitability of cortical inhibitory neurons in cranial dystonia.     

Pretarsal blepharospasm: Clinical and electromyographic characteristics

ObjectiveTo describe the clinical and electromyographic characteristics of blepharospasm caused by selective involvement of the pars pretarsalis of the orbicularis oculi muscle.MethodsClinical assessment and simultaneous electromyographic recordings from levator palpebrae superioris and pars orbitaria and pretarsalis of orbicularis oculi muscles were performed in patients with blepharospasm and primary failure to botulinum toxin injections. Patients with selective abnormal electromyographic activity of the pars pretarsalis of the orbicularis oculi muscle were identified and treated with selective pretarsal injections of botulinum toxin.ResultsWe found 24 patients with pretarsal blepharospasm confirmed by the electromyographic assessment. All of them were functionally blind. Three clinical-electromyographic patterns were identified: (a) Impairment of eyelid opening; (b) Increased blinking; (c) Spasms of eye closure combined with varying degrees of excessive blinking and impairment of eye-opening. Pretarsal injections of botulinum toxin induced a significant improvement in all patients and 50 % regained normal or near-normal vision. The clinical improvement was sustained after repeated pretarsal injections.ConclusionsPretarsal blepharospasm can be suspected on clinical grounds and it can be confirmed by electromyographic recordings.SignificanceRecognition of this type of blepharospasm is important because of its excellent response to botulinum toxin injections applied into the pretarsal part of the orbicularis oculi muscle.     

Surface electromyographic study of idiopathic cranial dystonia focused on the orbicularis oculi muscles

We studied 115 Japanese patients with idiopathic cranial dystonia (Meige disease), using surface electromyographu (EMG) focused on the orbicularis oculi muscles to classify the findings of the abnormal involuntary movements of this disease and to evaluate the pathophysiology of blepharospasm (BS). Surface EMGs at rest and at voluntary eyelid opening after eyelid closing were investigated. We found 62 (53.9%) patients exhibiting the overblinking type, 37 (32.2%) the tonic BS type, and 16 (13.9%) the normal type of behavior, considering the frequency of spontaneous blinking and presence of spasms. The present results suggest that BS is not a summation of blinking but a spatial and temporal extension of the orbicularis oculi muscle activity engaging in blinking, and the classification of the present study can support the investigation of the temporal characteristics of patients with this disease.     

Neurophysiological observations on the effects of botulinum toxin treatment in patients with dystonic blepharospasm.

Botulinum toxin treatment improves dystonic blepharospasm by inducing transient paresis of the orbicularis oculi muscle. It is not known if it also reduces the enhanced brainstem neuronal excitability found in this disorder. We have performed conventional electromyography (EMG) and blink reflex excitability studies on fifteen patients with blepharospasm before and after botulinum toxin treatment. Denervation signs were found with needle EMG in all treated muscles. Amplitude of the facial compound muscle action potential (CMAP) and R1 response was reduced after botulinum toxin injections. In blink reflex excitability studies, the recovery of R2 response was enhanced after treatment even when patients were tested at the time of maximal benefit from botulinum toxin injections. The results suggest that there is little influence of botulinum toxin treatment upon the enhanced excitability of brainstem interneurons in patients with blepharospasm.     

Speech-induced blepharospasm

Primary blepharospasm is an adult-onset dystonia typically present at rest and exacerbated by bright light, stress and voluntary movements of eyes and eyelids. Inconsistency or inducibility by activities involving muscles other than orbicularis oculi muscles are considered incongruous with typical primary blepharospasm, heralding the suspicion of psychogenicity. We report the clinical vignette of two patients manifesting an unusual presentation of primary blepharospasm, specifically triggered by voiced speech and associated with an otherwise ‘typical’ presentation of primary adult-onset dystonia in the lower face, larynx or upper limb. Speech-induced primary blepharospasm seems a rare occurrence, representing 1.3% of our clinic-based series of 149 patients with primary adult-onset primary blepharospasm. In these atypical patients, the feature of speech inducibility suggests that the abnormal surrounding inhibition between cortical subregions representing laryngeal and orbicularis oculi muscles might underlie dystonic overflow to the orbicularis oculi muscles following the voiced speech.     

Electrophysiological study of congenital facial paralysis

The common cause of neonatal facial asymmetry is facial nerve paralysis or "asymmetric crying facies syndrome". In the not uncommon later the lower lip, symmetrical at rest, becomes tilted to the so-called normal side when the patient is smiling or crying, as the congenital hypogenesis of sublabial muscles fail to pull down the lower lip in the opposite side. The electrophysiological differentiation between the two diseases has been performed by orbicularis oculi and oris reflexes with mechanically glabellar and supralabial tapping stimulation, respectively, in addition to needle and/or surface EMG recording. In the facial nerve paralysis of the case 1, R1 and R2 were absent in the orbicularis oculi and oris reflexes. EMG activity was completely lacking over the M. orbicularis oculi and oris innervated by facial nerve. On the contrary, the orbicularis oculi and oris reflexes were normal in the asymmetric crying facial of the case 2. EMG activity was absent only in the sublabial muscles including M. depressor anguli oris and/or M. depressor labii inferioris. Furthermore, needle EMG disclosed no spontaneous activity at rest, which was suggestive of no denervation in the sublabial muscles. It was, however, not possible to determine exactly which muscle the needle was inserted, the M. deprossor anguli oris or the M. depressor labii inferioris. The case 3 might be a variant of asymmetric crying facies with hypogenesis of M. orbicularis oris and/or oculi as well as the sublabial muscle, since the latency was normal but the amplitude was significantly attenuated in the components of orbicularis oculi and oris reflexes.(ABSTRACT TRUNCATED AT 250 WORDS)     

Blepharospasm in a patient with thymoma and positive anti-acetylcholine receptor antibody]

We report a rare case of a 70-year-old woman diagnosed as having blepharospasm with positive anti-acetylcholine receptor antibody. Blepharospasm developed in November, 2000, and increased in frequency, and worsened toward the evening. She complained of difficulty in her eyelid opening from October, 2002. Neurological examinations revealed blepharospasm and mild ptosis in both eyes. Tensilon test was negative. Waning and waxing were not detected in bilateral orbicularis oculi muscles by Harvey-Masland test. However, anti-acetylcholine receptor antibody was positive and thymoma in the anterior mediastinum was also found by the computed tomography of the chest. After the thymectomy, frequency of blepharospasm decreased. When blepharospasm worsened toward the evening, the co-existence of myasthenia gravis should be borne in mind.     

Apraxia of eyelid closure in a patient with progressive supranuclear palsy]

We reported a 68-year-old man with progressive supranuclear palsy who present with apraxia of eyelid closure. He showed horizontal and vertical supranuclear ophthalmoplegia, neck dystonic posture, pseudobulbar palsy and subcortical dementia. He opened his eyes almost all day long except for sleeping. His spontaneous blinking was noted at less than 1 per a minute. Although he closed his eyes reflexively, he could not close his eyes by verbal command. He occasionally closed his eyelids by using both hands. The surface electromyographic (EMG) findings revealed that the frequency of frontal muscle contraction did not decrease, and rather increased during verbal command to close his eyes. The contraction frequency of orbicularis oculi muscle did not increase by the command of voluntary eyelid closure. It is suggested that abnormal contractions of frontalis and orbicularis oculi muscles which are correlated in eyelid closing and opening might contribute to the apraxia of eyelid closure.     

Orbicularis oculi electromyogram in a girl with ocular myasthenia gravis]

A 12-month-old girl with ocular myasthenia gravis was reported. Electromyograms (EMG) of the orbicularis oculi muscle were studied during a period of 16 months. The degree of the waning phenomenon on EMG correlated well with that of her clinical symptoms. The study of post-tetanic exhaustion after repetitive electrical stimulation at 20 Hz for 4 seconds, was the most sensitive technique in the evaluation of the function of neuromuscular junction. EMG showed the waning phenomenon in the initial worsening after a high dose methylprednisolone therapy, and at the symptom-free stage without medication after the steroid therapy. In our patient, orbicularis oculi EMG was useful in the estimation of the severity of ocular myasthenia gravis and the effect of its treatment.     

Motor and non-motor symptoms in blepharospasm: clinical and pathophysiological implications

Journal of Neurology - Patients with blepharospasm in addition to involuntary contraction of the orbicularis oculi muscle also have non-motor symptoms (psychiatric, sleep, cognitive, and ocular)....     

Botulinum toxin improves lid opening delays in blepharospasm-associated apraxia of lid opening

Lid movement and EMG of the orbicularis oculi (OOc) were analyzed in 10 patients with apraxia of lid opening associated with blepharospasm before and after botulinum toxin treatment. The latencies to onset and to complete the eye opening and the time during which eye opening was sustained were studied in relation to OOc activity and compared with control values obtained in 12 healthy subjects. Following treatment there was an improvement of all lid opening measurements, a decrease of the abnormally prolonged OOc activity, and a reduction of the functional disability.     

Botulinum-induced alteration of nerve-muscle interactions in the human orbicularis oculi following treatment for blepharospasm

To assess longstanding alterations in human muscle innervation induced by botulinum toxin, we studied motor axons in the orbicularis oculi of nine patients previously injected with botulinum toxin for treatment of benign essential blepharospasm (BEB). Compared with untreated BEB and normal orbicularis oculi, muscle exposed to botulinum toxin developed persistent and cumulative alterations of innervation, including (1) thin, unmyelinated axonal collaterals that contact muscle end plates, (2) an increased number of muscle fibers innervated by individual terminal motor axons, (3) a profusion of unmyelinated axonal sprouts that end blindly, (4) an increased range of end plate sizes, and (5) multiple end plates on individual muscle fibers. The findings suggest that axonal sprouts which develop after botulinum-toxin-induced functional denervation can form new end plates. A single muscle fiber may then be innervated at separate sites by more than one axon.     

Comparison of preseptal and pretarsal injections of botulinum toxin in the treatment of blepharospasm and hemifacial spasm

Although the beneficial effect of subcutaneous injections of botulinum toxin type A (BTX-A) is well known in both blepharospasm and hemifacial spasm, the position of the injection sites around the orbicularis oculi may influence the effectiveness and side effects. Here we report results of preseptal and pretarsal BTX-A injections in 53 patients (25 blepharospasm and 28 hemifacial spasm) in whom we used both injection techniques successively. Pretarsal injections were used in 102 out of 186 treatments in blepharospasm group and in 84 out of 202 treatments in hemifacial spasm group. Pretarsal BTX-A treatment produced significantly higher response rate and longer duration of maximum response in both patient groups. This technique was also associated with a lower frequency of major side effects such as ptosis. We concluded that injections of BTX-A into the pretarsal, rather than the preseptal portion of the orbicularis oculi is more effective for treatment of involuntary eyelid closure due to contractions of this muscle. Received: 15 January 2001, Received in revised form: 11 May 2001, Accepted: 17 May 2001     

Electrical activation of the orbicularis oculi muscle does not increase the effectiveness of botulinum toxin type A in patients with blepharospasm

Background: Our primary aim in this study was to determine whether electrically induced activation of the injected muscle increases effectiveness of botulinum type A toxin (BonT‐A) in patients with blepharospasm (BPS). The second aim was to assess the safety of BonT‐A by investigating whether BonT‐A injection alters the excitability of blink reflex circuits in the brainstem. Methods: Twenty‐three patients with BPS received BonT‐A (Botox) injected bilaterally into the orbicularis oculi muscle at a standard dose. In 18 patients, electrically induced muscle activation of the orbicularis oculi muscle on one side was performed for 60 min (4 Hz frequency) in a single session, immediately after BonT‐A injection and in five patients for 60 min once a day for five consecutive days. The severity of BPS was assessed clinically with the BPS score. Compound muscle action potential (cMAPs) from the orbicularis oculi muscles were measured bilaterally. The blink reflex recovery cycle was studied at interstimulus intervals of 250 and 500 ms. Participants underwent clinical and neurophysiological assessment before BonT‐A injection (T0) and 2 weeks thereafter (T1). Results: Compound muscle action potential amplitude significantly decreased at T1 but did not differ between stimulated and non‐stimulated orbicularis oculi in the two groups. BonT‐A injection left the blink reflex recovery cycle tested on the stimulated and non‐stimulated sides unchanged. Conclusions: In patients with BPS, the electrically induced muscle activation neither increases the effectiveness of BonT‐A nor produces larger electrophysiological peripheral effects. The lack of BonT‐A‐induced changes in the blink reflex recovery cycle provides evidence that BonT‐A therapy is safe in patients with BPS.     

Lack of effect of botulinum toxin on cortical excitability in patients with cranial dystonia

The aim of this study was to verify whether botulinum toxin (BTX)-induced clinical improvement of cranial dystonia is associated with changes in the cortical silent period (SP), a measure of cortical excitability. By transcranial magnetic stimulation (TMS), high-intensity stimuli were delivered with a round coil centered at the vertex during a maximal muscle contraction of the orbicularis oculi. Motor evoked potentials (MEPs) and SPs were obtained from surface electrodes placed over the orbicularis oculi muscle before and 2 to 3 weeks after BTX-A injection into the affected muscles in 10 patients with cranial dystonia and 8 age-matched control subjects. BTX injection improved blepharospasm in all patients. Facial muscle SPs were significantly shorter in patients than in control subjects and did not significantly change after treatment, at the time of maximal clinical improvement. We conclude that the clinical improvement induced by BTX in patients with cranial dystonia is largely symptomatic. It does not appear to result from modulation of abnormal aspects of intracortical excitability, although these may play a role in craniofacial dystonia.     

Evoked EMG in juvenile ocular myasthenia gravis

We studied juvenile ocular myasthenia gravis (MG) with special reference to evoked EMG in orbicularis oculi muscle. The subjects consisted of 5 cases aged 1-4 years and 3 cases over 10 years. Young children were examined during drug-induced sleep. Stimulation was delivered to preauricular facial nerve, and M waves were recorded from ipsilateral orbicularis oculi muscle. Examinations were also carried out in thenar or hypothenar muscles by stimulating the median or ulnar nerves respectively. On Harvey-Masland test, 6 out of 8 cases showed waning of more than 10%. On M-wave recovery cycle, 3 out of 6 cases examined showed decrement during stimulation interval of 100 msec to 500 msec. In 2 of these, the peak of recovery cycle curve rose over 100% during stimulation interval of 30 to 60 msec on a usual dose treatment of anti-cholinesterase, while on prednisolone treatment this peak did not increase over 100% and the pattern of recovery cycle changed to almost normal. On post-tetanic cycle study, only 1 out of 4 cases examined showed post-tetanic facilitation and exhaustion. The response of the belly-tendon in the hand showed no abnormality. Although there still remains technical difficulty in the examination of evoked EMG in orbicularis oculi muscle, this examination is very useful in diagnosis, evaluation and understanding of pathophysiology of MG.     

A new variant of blepharospasm.

Ten patients who were unable to initiate or sustain eye opening in the absence of overt spasm of the orbicularis oculi, were investigated. In five, the problem was isolated. Three had Parkinson's disease and two progressive supra-nuclear palsy for between one to six years before the eye opening difficulty developed. The clinical features and electrophysiological investigation suggested that the disorder is a variant of blepharospasm due to abnormal contraction in the pre-tarsal orbicularis oculi.     

A case of bilateral blepharospasm responsive to edrophonium]

A case of bilateral blepharospasm who registered the efficacy of edrophonium was reported. The case is a 49-year-old female. She had been in good health until January, 1991 when she complained of difficulty in opening her eyes while driving. Thereafter the condition progressed to such a degree that she was unable to experience a comfortable life. Her blinking rate did not changed. The symptoms were triggered by stress or some physical action, such as walking or driving. They were attenuated by taking a bath, sleep or sedation. The severity of the symptoms varied during the day and from day to day. Neurological examination revealed bilateral spasms of the orbicular oculi muscles, and occasionally of the orbicular oris muscles, sternocleidmastoid muscles and the perinasal regions. Neither orolingual dyskinesia nor other involuntary movements were detected. Surface electromyography (EMG) disclosed tonic discharges mainly from the orbicular oculi muscles. The abnormal spasm disappeared with the injection of edrophonium chloride. The test for the serum antiacetylcholine receptor antibody was negative and a repetitive stimulation EMG showed no waning phenomenon. No thymoma or thymus abnormalities were detected by pneumomediastinography. A needle EMG revealed neurogenic change in the distal portion of the limbs. A single fiber EMG showed elongation of the jitter value and the blocking phenomenon. Although distigmine bromide was ineffective against the spasm, pyridostigmine bromide and the local injection of botulinum toxin were very effective.(ABSTRACT TRUNCATED AT 250 WORDS)     

Involuntary closure of eyelids in parkinsonism. Electrophysiological evidence for prolonged inhibition of the levator palpebrae muscles

Involuntary closure of eyelids (ICE), a phenomenon variously interpreted as blepharospasm and apraxia of lid opening, is occasionally observed in parkinsonism. Nine patients (4 with Parkinson's disease, 2 with post-encephalitic parkinsonism, and 3 with supranuclear palsy) with prominent ICE, were studied by electromyographic recording of the eye muscles. ICE episodes were shown to be dependent upon prolonged, irregular inhibition of the normal tonic activity of the levator palpebrae superioris (LPS) muscle causing drooping of the upper eyelid without any corresponding activation of the orbicularis oculi (OO) muscle. Nevertheless, some degree of excessive, widely fluctuating OO activity was present in seven of the patients. Blepharocolysis (from Gr. blepharon, eyelid, and kolysis inhibition) is put forward as the term to designate ICE episodes resulting from abnormally long inhibition of the LPS muscles and should be differentiated electrophysiologically from blepharospasm, excessive OO muscles activity. Abnormal influences from basal ganglia acting on brainstem structures that regulate blinking may falicitate either of the two components of normal blinking resulting in ICE due to the predominance of LPS inhibition (blepharocolysis), the predominance of OO activation (blepharospasm) or a combination of the two.