Benzalkonium chloride-induced denervation of orbicularis oculi muscle in rabbits.

PURPOSE: To examine the potential for benzalkonium chloride (BAK) to cause denervation of the orbicularis oculi muscle (OOM) in a rabbit model. METHODS: Pigmented rabbits were separated into five groups consisting of five rabbits each. Group 1 was injected with 1 mL of BAK 0.25% in the OOM of the upper eyelid. Group 2 was injected with 1 mL of BAK 0.5%. Group 3 included untreated controls. Groups 4 and 5 underwent surgical severing of the facial nerve (to cause complete paralysis of the OOM). Strength-duration curves for electrical stimulation of muscle twitches were measured for each group and chronaxie values were calculated to determine innervation status. Groups 1 and 4 were stimulated at 1 week postintervention while groups 2 and 5 were stimulated at 4 weeks postintervention. The rabbits were then sacrificed and the eyelids sent for histological analysis. RESULTS: In group 1, all five rabbits demonstrated denervation of the OOM in the injected area. In group 2, one rabbit developed an abscess at the injection site and was sacrificed at 1 week. Of the remaining four rabbits, two showed complete denervation and two showed denervation with evidence of partial reinnervation. The histology demonstrated marked atrophy of the OOM for BAK-treated rabbits when compared with controls. In group 3, all five rabbits showed normal OOM function. In groups 4 and 5, all rabbits showed denervation of the OOM and histological evidence of muscle atrophy similar to groups 1 and 2. CONCLUSIONS: BAK causes denervation when injected into the OOM in rabbits. The clinical relevance of this finding may be the onset of lagophthalmos and eyelid retraction in patients with chronic BAK exposure.

Resolution of blepharospasm after chronic subdural haematoma evacuation: A case report.

Blepharospasm in connection with chronic subdural haematoma is an uncommon pathology and usually subsides after treatment of the haematoma. Different mechanical and vascular factors may play a role by affecting domapinergic transmission in basal ganglia. A case of a 72-year-old patient is presented, who developed transient blepharospasm as a result of a chronic subdural haematoma and whose symptoms regressed after surgical management.

Use of botulinum toxin in dentistry.

A growing number of dentists are providing botulinum toxin to patients. The research presented here outlines potential uses of Botox related to oral health and facial problems as compared to traditional treatment methods. The administration of Botox (historically done by dermatologists and neurologists) may fall under dentists' jurisdiction, as their training and knowledge encompasses the entire head and neck. A review is made of the literature, based on Ovid and PubMed searches, selecting articles describing the injection of botulinum toxin A in areas related to the oral cavity and the face, excluding cosmetic purposes.

Double-clip technique in cataract surgery using topical anesthesia.

We describe a simple technique that reduces the effect of blepharospasm in the presence of sub-Tenon's or topical anesthesia without the administration of a lid block or a reduction in adequate analgesia.

Controlling blepharospasm effect during applanation tonometry using the Volk SuperField Lid Lens Adapter.

PURPOSE: To describe a practical clinical technique that can be used to control the effect of blepharospasm during applanation tonometry. METHODS: The Volk Superfield NC Lid Lens Adapter is used to keep the eye open and prevent the squeezing effect of orbicularis oculi in blepharospasm. RESULTS: This helpful tool can be used when blepharospasm becomes a problem that interferes with accurate intraocular pressure measurement. CONCLUSIONS: The technique is potentially useful and relatively easy to perform.

Apraxia of lid opening: dose-dependent response to carbidopa-levodopa.

A 67-year-old woman with an 8-year history of Parkinson's disease and Lewy body dementia experienced difficulty in opening her eyelids (apraxia of lid opening [ALO]); she could close them without difficulty. This problem emerged 2 weeks after the patient's dosage of carbidopa 50 mg-levodopa 200 mg 3 times/day was decreased to twice/day. Two weeks after the onset of ALO the patient visited her physician, who suspected carbidopa-levodopa of causing the problem; the drug was discontinued. When the patient's condition worsened rather than improved, she was referred to a neuro-ophthalmologist, who confirmed the diagnosis of ALO. However, the neuro-ophthalmologist noted that this may not have been a true apraxia but rather a form of sustained blepharospasm that prevented the eyelid from opening. Carbidopa-levodopa was restarted, and her condition improved dramatically when her dosage was increased gradually to carbidopa 50 mg-levodopa 200 mg in the morning and at noon, and carbidopa 25 mg-levodopa 100 mg in the evening. Clinicians should be aware of adverse reactions, such as AOL, in patients taking carbidopa-levodopa who have dementia of the Lewy body type.

Anatomical study of the variations in innervation of the orbicularis oculi by the facial nerve.

While the divisions of the facial nerve in the face are well known, the innervation of the orbicularis oculi by the different distal branches of the facial nerve is poorly described. To determine which branches of the facial nerve play a role in this innervation, the facial nerve was dissected in 30 fresh cadavers. The innervation of this muscle was in the form of two plexuses, a superior one, most often (93%) formed by the union of the temporal and superior zygomatic branches, and an inferior one, usually formed (63%) by the union of the inferior zygomatic and superior buccal branches. This new mode of innervation explains how, without damage to both plexuses, innervation of orbicularis oculi by the facial nerve remains functional. It also explains the often unsatisfactory results of treatment of primary blepharospasm, and the unusual character of palsies of this muscle in cervicofacial lifts.

Topical anesthesia without intracameral lidocaine in cataract surgery.

PURPOSE: To evaluate the efficacy of topical anesthesia with oxybuprocaïne 0.4% without intracameral lidocaïne as an alternative to peribulbar or retrobulbar anesthesia in cataract surgery. METHODS: Fifty-eight patients (eighty-two eyes) were included in this study. All patients received topical anesthesia with oxybuprocaïne 0.4%. No intracameral lidocaïne was used at the start of the intervention. Seventy-five per cent of patients received oral sedation with lorazepam 2.5 mg. All surgery was done using a superior corneal incision and phacoemulsification followed by a foldable IOL implantation. Subjective pain was assessed at 4 intervals during surgery using a 4-point pain scale. All patients were evaluated for intraoperative eye motility and blepharospasm. Patient and surgeon satisfaction was measured with a 4-point satisfaction scale. RESULTS: 15% of patients experienced mild pain during phaco and 43% had mild pain during corneal suturing. No patient had severe pain during the operation. In 4% of patients, intracameral lidocaïne was used to relieve pain. The surgeon and patient satisfaction was high. No eye movements or blepharospasm were recorded in 75% and 62% of cases respectively. No serious complications occurred. CONCLUSION: Topical anesthesia is a safe and effective alternative to peribulbar and retrobulbar anesthesia in corneal cataract surgery for the experienced surgeon.

The control of blepharospasm by essential fatty acids.

Dopamine depletion induced by administration of Ro4-1284 produces a condition of rapid and repeated eye blinking in rats. This condition mimics the human disorder, blepharospasm, which often accompanies parkinsonism and other dopamine deficiency disorders. When given a 3-week course of a compound (SR-3) developed from a specific ratio of two free polyunsaturated fatty acids - linoleic acid and alpha-linolenic acid - the eye blinking rate following administration of Ro4-1284 is reduced to saline and no drug control levels. These results suggest a favorable prospect for essential fatty acids in general, and SR-3 in particular, to provide an improved therapeutic option for the clinical management of benign essential blepharospasm.

The effects of tetanus toxin on the orbicularis oculi muscle.

PURPOSE: Tetanus toxin can cause localized neuromuscular weakness, but it also can produce systemic tetany. The action of tetanus toxin on the orbicularis muscle has not been studied in animals immunized to prevent systemic tetany. Our objective was to determine whether tetanus toxin could be used to treat orbicularis oculi muscle spasms. METHODS: We analyzed the clinical, electrophysiologic, and histopathologic effects of tetanus toxin injected into the orbicularis oculi muscle of rabbits with passive immunity to tetanus toxin. In six rabbits, the orbicularis oculi function in both eyes was assessed clinically, and the baseline orbicularis oculi muscle action potential was measured physiologically with electromyography (EMG). The rabbits then were immunized against tetanus toxin with tetanus immunoglobulin for immediate and definitive immunity. Tetanus toxin was injected into the left orbicularis oculi muscles, leaving the right eyes as controls. Ten days later, the rabbits were again assessed by clinical examination and with EMGs on both the injected side and the noninjected side. The animals were killed at 14 days, and the orbicularis muscle was removed from both sides. The injected and control tissues were examined microscopically for signs of neuromuscular denervation. RESULTS: All six rabbits showed weakness in eye closure on the side injected with tetanus toxin. In addition, four rabbits developed complete ear ptosis on the tetanus toxin injected side because of spread of the toxin to adjacent ear muscles. EMGs showed both a denervation of the orbicularis oculi muscle and a poor blink potential on the side injected with tetanus toxin. Histopathologic studies of the orbicularis oculi muscle injected with tetanus toxin showed angulation of both slow and fast types of muscle fibers compatible with neuromuscular denervation. CONCLUSIONS: Tetanus toxin can cause localized orbicularis oculi weakness, as documented clinically, physiologically, and microscopically, without producing systemic tetany in immunized rabbits. Tetanus toxin may have a potential application in the treatment of blepharospasm and hemifacial spasm.

[Method of prevention and treating the accommodation cramp and progressive myopia in children]. / Sposob profilaktiki i lecheniia spazmov akkomodatsii i progressiruiushchei miopii u detei.

A new method for treating the accommodation cramp and progressive myopia in children consists in transferring the glance from a close TV screen to a far one. One of the tasks of this method is to turn a computer game from a factor deteriorating the accommodation into a factor improving it. The picture is automatically transferred from one TV to the other every 10 seconds. Sixty-five children were followed up. The volume of relative accommodation improved, the progress of myopia in a year was 0.045 versus 0.5 diopters in the control group.

Personal defense sprays: effects and management of exposure.

BACKGROUND: Most personal defense sprays contain o-chlorobenzylidene malononitrile (CS), w-chloroacetophenone (CN), oleoresin capsicum (OC), or a combination of these ingredients as the active agent. They are designed to incapacitate by causing acute ocular irritation, lacrimation, conjunctivitis, blepharospasm, and mild to moderate respiratory distress. METHODS: To assess the ocular effects of sprays containing OC as the active agent. Snellen visual acuities and anterior segment appearances of 22 police officers were determined before and after spray exposure. To assess the effects of OC spray contamination on soft contact lenses, four brands of lenses were sprayed and cleaned twice with an alcohol-based cleaner. Gas chromatography was used to search for residual OC in the lenses. RESULTS: All officers experienced intense blepharospasm, lacrimation, conjunctivitis, and incapacitation as the result of spray exposure. Acute effects lasted about 5 to 10 min, with relatively complete recovery occurring in about 30 to 60 min. All had significant conjunctivitis, and some had water-drop-shaped corneal defects that stained with fluorescein. These defects resolved within 24 hours without treatment. OC residue was found to be present in the soft lenses that had been sprayed and cleaned twice. CONCLUSIONS: Optometrists can manage uncomplicated spray exposure patients by directing at-home irrigation with water, and following up with an in-office examination. Soft lenses contaminated by OC spray should be discarded.

Local anaesthesia for eye surgery without a facial nerve block.

Traditionally, local anaesthesia for cataract surgery requires retrobulbar blockade to be supplemented with a facial nerve block in order to prevent blepharospasm. In this study retrobulbar block using a larger volume of local anaesthetic without facial nerve block is compared with the combined technique in 50 patients. The adequacy of the two techniques was assessed by the surgeon according to eye motility (in four different planes), lid motility and eye softness and an overall surgical assessment was made at the end of the procedure. Blepharospasm did not occur. The operating conditions were equally good in both groups (p > 0.05). These results suggest that good operating conditions for cataract operations can be provided by retrobulbar block alone without supplementary facial nerve block.

Head and/or torso cooling during simulated cockpit heat stress.

Liquid-conditioned garments (LCG's) may be useful in alleviating heat stress on aircrew members. This study evaluated the effects of a liquid-cooled vest and/or cap on subjects exposed to a thermal environment which simulated the stress of low-level flight in hot weather. The chamber was set at dry bulb temperature 35 degrees C, wet bulb temperature 26 degrees C, and black globe temperature 43 degrees C. Subjects were eight men, aged 23-45 yr. Each subject was studied in four 100-min exposures: uncooled control (XX); head cooling only (HX); torso cooling only (XT); and combined head and torso cooling (HT). Cooling effects were evaluated by using rectal temperature (Tre); heart rate (HR); sweat rate (SRF and SRT for forehead and total body, respectively); and subjective comfort. Uncooled runs (XX) produced final values: Tre = 37.8 degrees C, HR = 94 beats/min, SRT = 25 g/m2 X h and SRF = 45 g/m2 X h. Combined head and torso cooling maintained the subjects at nearly their initial (baseline) state. Cap effects per se were assessed by comparing HX to XX, and HT to XT. Head cooling proved 2-3 times as efficient as torso cooling, although limited by the small surface area involved. We conclude that the specific effects of head cooling in improving comfort and diminishing forehead sweating, as well as the efficient systemic cooling observed, justify further work on cockpit applications.