Botulinum toxin treatment of acute sixth and third nerve palsy

An evaluation of 30 years' experience in the use of botulinum toxin injections in the management of sixth nerve palsies

INTRRODUCTION

Sixth nerve palsy is the most common type of extraocular muscle palsy. The therapy options in sixth nerve palsies include monitoring with or without conservative treatment, botulinum toxin injections or strabismus surgery. The aim of this retrospective study was to compare botulinum toxin (BT) injections into the medial rectus to conservative treatment in sixth nerve palsies. The rate of patients improved after intervention and treatment outcomes for the two treatment options were be evaluated at a German tertiary referral center.

METHODS

A service evaluation was conducted on adult patients with sixth nerve palsy. Patient files were reviewed and data including abduction deficit and size of deviation were collected retrospectively. Patients which presented between January 1987 and April 2022 were considered. Patients were allocated into two treatment groups: BT injected into medial rectus or conservative treatment, which included observation, providing occlusion and Fresnel prisms. Inclusion criteria were attendance of two visits with orthoptic assessment. Exclusion criteria included presence of further oculomotor palsies, strabismus, strabismus surgery and suppression. Non-parametric statistical analysis was conducted using IBM® SPSS Statistics.

RESULTS

A total of 606 adult patients with unilateral or bilateral sixth nerve palsy attended during the named period. A total of 137 adult patients met the inclusion criteria. Of which, 36 had a bilateral palsy, 101 had a unilateral palsy. 45.26% (n = 62) were treated with BT injections and 54.75% (n = 75) were treated conservatively. The median initial abduction deficit was greater in the BT group, (-4 to -5 after Scott and Kraft) than in the conservative treatment group (-1). The initial angle of deviation at distance was significantly larger in the BT group than in the conservative treatment group (p =  <0.001). The rate of improvement in the BT group was 24.19% (n = 15) and 20% (n = 15) in the conservative treatment group. When excluding longstanding palsies rates of improvement in both groups increased to 28.85%. The improvement of the angle of deviation at distance in all patients was greater in the BT group (p = <.001). The improvement of abduction in bilateral palsies were greater in the BT group (p = .016), but in unilateral palsies, there was no significant difference in abduction improvement in the two treatment groups (OD p = .3, OS p = .406).

CONCLUSION

This service evaluation found that BT injection into medial rectus in unilateral and bilateral sixth nerve palsies did not increase the rate of improvement compared to conservative treatment. But BT injections reduced the angle of deviation to a greater extent than conservative treatment. Additionally, BT was able to improve abduction in bilateral palsies to a greater extent than conservative treatment. It is recommended a BT injection is considered in symptomatic bilateral sixth nerve palsies to enable fixation and improved ocular motility. More research is needed to verify reliable clinical guidelines for the use of BT in sixth nerve palsies.

Botulinum Toxin Injection for the Treatment of Third, Fourth, and Sixth Nerve Palsy: A Meta-Analysis

The efficacy of botulinum toxin injection for the treatment of third, fourth, and sixth nerve palsy was evaluated. PubMed, Scopus, EMBASE, Web of Science, and Google Scholar databases were searched. Data about the duration of palsy (acute vs chronic), cause of the palsy, type of toxin used, mean dose, and other background characteristics were collected. Outcome variables were success rate (defined by alleviation of diplopia or reduction in eye deviation) and standardized mean difference of prism diopter and abduction deficit before and after injection. The Joanna Briggs Institute checklist was implemented for the risk of bias assessment. The analysis included 38 articles, comprising 643 patients. The overall treatment success rate in acute and chronic nerve palsy was 79% and 33%, respectively. The success rate was not significantly different between different subgroups of age, type of botulinum toxin, pre-injection prism diopter, etiology of the palsy, duration of follow-up, and mean dose of botulinum toxin injection. However, in both acute and chronic palsy, diabetes etiology was accompanied by the highest success rate. Overall symptomatic response to botulinum injection was 84% (95% CI: 67% to 96%), whereas functional response was observed in 64% (95% CI: 47% to 79%) of the patients. The odds ratio for the success rate of treatment of palsies with botulinum toxin versus expectant management was 2.67 (95% CI: 1.12 to 6.36) for acute palsy and 0.87 (95% CI: 0.17 to 4.42) for chronic palsy. Botulinum toxin can be used for the treatment of acute third, fourth, and sixth nerve palsy, especially in patients with acute palsy and more severe tropia. [J Pediatr Ophthalmol Strabismus. 2024;61(3):160-171.].

Bilateral horizontal gaze palsy as an initial presentation of a clinically isolated syndrome: A case report

Multiple sclerosis (MS) is the most common demyelinating disease affecting the central nervous system. It has a wide range of manifestations and commonly affects the visual system. Many patients with MS report decreased vision, diplopia, nystagmus, and abnormal ocular motility. Nevertheless, bilateral horizontal gaze palsies are exceptionally rarely seen. We present the case of a 24-year-old female who came to our pediatric ophthalmology clinic complaining of bilateral horizontal gaze palsy, photophobia, and eye pain for 2 days. Although the patient had a family history of MS, there was no similar or previous complaint, with an unremarkable past medical and surgical history. During the examination, she was found to have a complete bilateral absence of horizontal saccade and pursuit, with slight limitations in vertical ones. There was no nystagmus or skew deviation, and the rest of the cranial nerves (CNs) were intact. Her ocular vital signs were normal, and her corrected visual acuity was 20/20 with full-color vision. The rest of the physical and neurological examinations were unremarkable. After referral to neurology, the magnetic resonance imaging showed multiple hyperintense lesions in deep white matter, pons, and midbrain. The correlation of imaging findings with clinical presentation confirmed the diagnosis of a clinically isolated syndrome. Extra-ocular motility (EOM) significantly improved after pulse steroid therapy and five sessions of plasma exchange, but the patient developed 35 prism diopter of acquired concomitant esotropia. She underwent a right medial rectus botulinum toxin injection which dramatically improved her condition, and became orthotropic during the last 2 months of follow-up after the injection.

Binocular Visual Rehabilitation in Paralytic Strabismus by Botulinum A Toxin Chemodenervation

Purpose

To investigate the effect of botulinum A toxin (BTXA) chemodenervation in paralytic strabismus patients without surgical correction.

Methods

A retrospective chart review of 51 patients who were diagnosed as paralytic strabismus and underwent BTXA chemodenervation was performed. The patients were divided into four groups according to the cause of paralytic strabismus of vasculopathy, neoplasm, trauma, and idiopathic. They were also divided into two groups of early and late treatment according to the initiation time of BTXA chemodenervation after the onset of strabismus (3 months), and of the initial strabismus type of exotropia and esotropia. We investigated the changes of angle of deviation and diplopia after BTXA chemodenervation.

Results

The average deviation of angles decreased by 25.2 prism diopter (PD) (35.1 to 9.9 PD) in total patients, and the overall success rate was 64.7% (33 by 51), and the there was no statistically significant difference in success rate between each group divided by the cause of paralytic strabismus. According to the treatment timing, the deviation of the angle decreased by 28.0 PD (36.8 to 8.8 PD) in the early treatment group, and 21.3 PD (33.5 to 12.2 PD) in late treatment group at the time of the last postinjective follow-up. According to the initial strabismus type, the average angle of deviation decreased by 20.3 PD (35.6 to 15.3 PD) in exotropia group by cranial nerve 3 palsy, and 24.4 PD (32.5 to 8.1 PD) in esotropia by cranial nerve 6 palsy.

Conclusions

BTXA chemodenervation reduced the angle of deviation and the number of patients with diplopia regardless of the cause of paralytic strabismus. Early BTXA chemodenervation can be considered as the first treatment of choice in paralytic strabismus, especially in esotropia patients.

[Outcomes after medial rectus recession and lateral rectus plication for abducens nerve palsy: A retrospective study]

BACKGROUND

Abducens nerve palsy (ANP) is the most common oculomotor palsy. This study aimed to evaluate the efficacy of medial rectus recession with lateral rectus plication in patients with unilateral acquired ANP and to describe the etiologies of this condition.

METHODS

Thirty-one patients were included in this retrospective single-center study conducted between 2000 and 2019 at the university research hospital in Tours. The following data were collected before and after surgery: diplopia, oculomotor deviations, ocular motility, and head posturing.

RESULTS

The mean age was 55.9±18.9 years and the mean postoperative follow-up was 11±4 months. Postoperatively, the patients had significant reduction in diplopia in primary position (P<0.001), in abduction of the affected eye (P<0.001) and in distance and near horizontal deviations (P<0.001). Abduction of the affected eye was significantly improved (P<0.001), but reduction in head posturing was insignificant (P=0.27). The etiologies were as follows: trauma (8 patients, 26%), neoplasm (6 patients, 16%), stroke-related (5 patients, 16%), compressive (5 patients, 16%), undetermined (5 patients, 16%) and inflammatory (2 patients, 6%).

CONCLUSION

Medial rectus recession with lateral rectus plication is an effective procedure in reducing diplopia and ocular deviation in unilateral acquired ANP and may be used as a first-line intervention regardless of the initial ocular motility limitation in abduction. The causes are mainly traumatic but remain undetermined in one case out of six.

Interventions for eye movement disorders due to acquired brain injury

BACKGROUND

Acquired brain injury can cause eye movement disorders which may include: strabismus, gaze deficits and nystagmus, causing visual symptoms of double, blurred or 'juddery' vision and reading difficulties. A wide range of interventions exist that have potential to alleviate or ameliorate these symptoms. There is a need to evaluate the effectiveness of these interventions and the timing of their implementation.

OBJECTIVES

We aimed to assess the effectiveness of any intervention and determine the effect of timing of intervention in the treatment of strabismus, gaze deficits and nystagmus due to acquired brain injury. We considered restitutive, substitutive, compensatory or pharmacological interventions separately and compared them to control, placebo, alternative treatment or no treatment for improving ocular alignment or motility (or both).

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (containing the Cochrane Eyes and Vision Trials Register) (2017, Issue 5), MEDLINE Ovid, Embase Ovid, CINAHL EBSCO, AMED Ovid, PsycINFO Ovid, Dissertations & Theses (PQDT) database, PsycBITE (Psychological Database for Brain Impairment Treatment Efficacy), ISRCTN registry, ClinicalTrials.gov, Health Services Research Projects in Progress (HSRProj), National Eye Institute Clinical Studies Database and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP). The databases were last searched on 26 June 2017. No date or language restrictions were used in the electronic searches for trials. We manually searched the Australian Orthoptic Journal, British and Irish Orthoptic Journal, and ESA, ISA and IOA conference proceedings. We contacted researchers active in this field for information about further published or unpublished studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) of any intervention for ocular alignment or motility deficits (or both) due to acquired brain injury.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies and extracted data. We used standard methods expected by Cochrane. We employed the GRADE approach to interpret findings and assess the quality of the evidence.

MAIN RESULTS

We found five RCTs (116 participants) that were eligible for inclusion. These trials included conditions of acquired nystagmus, sixth cranial nerve palsy and traumatic brain injury-induced ocular motility defects. We did not identify any relevant studies of restitutive interventions.We identified one UK-based trial of a substitutive intervention, in which botulinum toxin was compared with observation in 47 people with acute sixth nerve palsy. At four months after entry into the trial, people given botulinum toxin were more likely to make a full recovery (reduction in angle of deviation within 10 prism dioptres), compared with observation (risk ratio 1.19, 95% CI 0.96 to 1.48; low-certainty evidence). These same participants also achieved binocular single vision. In the injection group only, there were 2 cases of transient ptosis out of 22 participants (9%), and 4 participants out of 22 (18%) with transient vertical deviation; a total complication rate of 24% per injection and 27% per participant. All adverse events recovered. We judged the certainty of evidence as low, downgrading for risk of bias and imprecision. It was not possible to mask investigators or participants to allocation, and the follow-up between groups varied.We identified one USA-based cross-over trial of a compensatory intervention. Oculomotor rehabilitation was compared with sham training in 12 people with mild traumatic brain injury, at least one year after the injury. We judged the evidence from this study to be very low-certainty. The study was small, data for the sham training group were not fully reported, and it was unclear if a cross-over study design was appropriate as this is an intervention with potential to have a permanent effect.We identified three cross-over studies of pharmacological interventions for acquired nystagmus, which took place in Germany and the USA. These studies investigated two classes of pharmacological interventions: GABAergic drugs (gabapentin, baclofen) and aminopyridines (4-aminopyridines (AP), 3,4-diaminopyridine (DAP)). We judged the evidence from all three studies as very low-certainty because of small numbers of participants (which led to imprecision) and risk of bias (they were cross-over studies which did not report data in a way that permitted estimation of effect size).One study compared gabapentin (up to 900 mg/day) with baclofen (up to 30 mg/day) in 21 people with pendular and jerk nystagmus. The follow-up period was two weeks. This study provides very low-certainty evidence that gabapentin may work better than baclofen in improving ocular motility and reducing participant-reported symptoms (oscillopsia). These effects may be different in pendular and jerk nystagmus, but without formal subgroup analysis it is unclear if the difference between the two types of nystagmus was chance finding. Quality of life was not reported. Ten participants with pendular nystagmus chose to continue treatment with gabapentin, and one with baclofen. Two participants with jerk nystagmus chose to continue treatment with gabapentin, and one with baclofen. Drug intolerance was reported in one person receiving gabapentin and in four participants receiving baclofen. Increased ataxia was reported in three participants receiving gabapentin and two participants receiving baclofen.One study compared a single dose of 3,4-DAP (20 mg) with placebo in 17 people with downbeat nystagmus. Assessments were made 30 minutes after taking the drug. This study provides very low-certainty evidence that 3,4-DAP may reduce the mean peak slow-phase velocity, with less oscillopsia, in people with downbeat nystagmus. Three participants reported transient side effects of minor perioral/distal paraesthesia.One study compared a single dose of 4-AP with a single dose of 3,4-DAP (both 10 mg doses) in eight people with downbeat nystagmus. Assessments were made 45 and 90 minutes after drug administration. This study provides very low-certainty evidence that both 3,4-DAP and 4-AP may reduce the mean slow-phase velocity in people with downbeat nystagmus. This effect may be stronger with 4-AP.

AUTHORS' CONCLUSIONS

The included studies provide insufficient evidence to inform decisions about treatments specifically for eye movement disorders that occur following acquired brain injury. No information was obtained on the cost of treatment or measures of participant satisfaction relating to treatment options and effectiveness. It was possible to describe the outcome of treatment in each trial and ascertain the occurrence of adverse events.

The role of Botulinum toxin in management of acute traumatic third-nerve palsy

PURPOSE

To study the effect of botulinum toxin A injection in the management of paralytic exotropia resulting from acute traumatic third (oculomotor) nerve palsy.

METHODS

Nine patients with acute traumatic partial third-nerve palsy of less than 2 months' duration were treated by injection of botulinum toxin A into the ipsilateral lateral rectus muscle. The horizontal deviation angles before and after the injections were recorded. A distance exotropia of less than 10(Delta) or absence of diplopia in the primary position at the last follow-up was defined as recovery.

RESULTS

The mean preinjection deviation in the primary position was 48.3(Delta) of exotropia, and the mean postinjection deviation in the primary position was 14.2(Delta) at the last follow-up. Seven patients experienced recovery and regained single binocular vision in the primary position. The overall recovery rate was 77.8%. Two patients did not recover and subsequently underwent strabismus surgery.

CONCLUSIONS

Patients with acute traumatic partial third-nerve palsy treated by injection of botulinum toxin A in the lateral rectus muscle showed marked recovery when injection was performed within 2 months of the onset of palsy. Botulinum toxin injection into the lateral rectus muscle may provide temporary relief of symptoms in some patients and seems to be a useful treatment option in cases of acute traumatic third nerve palsy in the short-term.

Botulinum toxin in the treatment of strabismus. A review of its use and effects

Botulinum Toxin as a medical therapy was introduced by Dr Alan Scott more than 20 years ago. The first clinical applications of Botulinum Toxin type A (BT-A) were for the treatment of strabismus and for periocular spasms. Botulinum Toxin type A is often effective in small to moderate angle convergent strabismus (esotropia) of any cause, and may be an alternative to surgery in these cases. Botulinum Toxin type A may have a role in acute or chronic fourth and sixth nerve palsy, childhood strabismus and thyroid eye disease. The use of BT-A for strabismus varies enormously in different cities and countries for no apparent reason. Botulinum Toxin type A may be particularly useful in situations where strabismus surgery is undesirable. This may be in elderly patients unfit for general anaesthesia, when the clinical condition is evolving or unstable, or if surgery has not been successful. Botulinum Toxin type A can give temporary symptomatic relief in many instances of bothersome diplopia irrespective of the cause. Ptosis and acquired vertical deviations are the commonest complications encountered. Vision-threatening complications are rare. Repeated use of BT-A is safe.

[Botulinum toxin injections for the treatment of strabismus. Which indications are still useful today?]

Botulinum toxin treatment was originally developed 25 years ago by Alan B. Scott to produce reversible weakening of extraocular eye muscles in humans (chemodenervation). The following uses are still helpful today in comparison with eye muscle surgery, prism applications etc.: Preoperative evaluation of possible postoperative diplopia in patients in whom this cannot be done by means of prisms or traction test, etc. Acute paretic loss of ocular muscle function when surgical treatment of the ocular muscles is not yet possible but the patient is obviously disturbed by diplopia or a forced head posture. This applies especially to VI cranial nerve paresis. Depending on the surgical approach in VI nerve palsies, Botulinum toxin may be injected in the medial rectus muscle before muscle transposition surgery to loosen contracture. Strabismus in acute Graves' disease. In strabismus in other conditions, Botulinum toxin is mostly inferior surgical treatment of the ocular muscles; this is the case, for example in congenital esotropia or horizontal strabismus in adults. While the reversibility of the Botulinum toxin A effect by fading out after 3-4 months is seen as an advantage, it does also mean that in these cases of constant strabismus it is necessary to keep repeating the injections.

Aberrant regeneration of the oculomotor nerve: implications for neurosurgeons

✓Aberrant regeneration of cranial nerve III, otherwise known as oculomotor synkinesis, is an uncommon but well-described phenomenon most frequently resulting from trauma, tumors, and aneurysms. Its appearance usually follows an oculomotor palsy, but it can also occur primarily without any preceding nerve dysfunction. It is vital that neurosurgeons recognize this disorder because it may be the only sign of an underlying cavernous tumor or PCoA aneurysm. The tumor most often implicated is a cavernous or parasellar meningioma, but any tumor that causes compression or disruption along the course of the oculomotor nerve may cause primary or secondary misdirection. The most common clinical signs of oculomotor synkinesis consist of elevation of the upper eyelid on attempted downward gaze or adduction, adduction of the eye on attempted upward or downward gaze, and constriction of the pupil on attempted adduction. The authors present the largest series of patients with oculomotor synkinesis, including those in whom it developed after neurosurgical intervention, to illustrate various presentations. In addition, the various mechanisms that contribute to synkinesis are reviewed. Last, the treatment strategies for both oculomotor palsies and synkinesis are discussed.

Botulinum toxin treatment for acute traumatic complete sixth nerve palsy

AIMS

To investigate the benefits of botulinum toxin (BTX) injection for acute unilateral complete sixth nerve palsy caused by trauma.

METHODS

We retrospectively reviewed patients treated for acute unilateral complete sixth nerve palsy caused by head injury during a 10-year period (between March 1993 and February 2003) in our hospital. The BTX treatment group was defined as patients who received BTX injection within 3 months of injury. Patients who presented within 3 months of trauma, and had no previous BTX injection or surgery were enrolled as the conservative treatment group. Comparison of the patient demographics, palsy characteristics, angle of deviations, and recovery rates were made between the two groups.

RESULTS

In all, 33 patients were enrolled by our inclusion criteria. Of these, 19 patients were treated conservatively, and 14 patients were treated with BTX. A total of 79% of our patients presented with abduction deficit of grade -5. The results showed that there was no significant difference in the outcome for the two groups based on age, gender, time to presentation, severity, and initial angle of deviation. The BTX group had a higher recovery rate than the conservative treatment group (64.3 vs 26.3%, P=0.028). Among 26 patients with grade -5 abduction deficit, the recovery rate was higher in the BTX-treated patients than in the conservatively treated patients, which had no statistical significance (50 vs 18.8%, P=0.09).

CONCLUSION

BTX facilitates recovery of acute traumatic complete sixth nerve palsy in severely injured patients.

Botulinum toxin for sixth nerve palsies in children with brain tumors

PURPOSE

Sixth nerve palsies in children with brain tumors have a low rate of spontaneous recovery. Botulinum toxin has been used to treat sixth nerve palsies. In this study, we review outcomes for children with brain tumors and sixth nerve palsies, some of whom were treated with botulinum toxin.

METHODS

To determine whether botulinum toxin effected the outcome of children with sixth nerve palsies and brain tumors, a retrospective review of charts was conducted for patients identified as having brain tumors and sixth nerve palsies after evaluation at the St Jude Children's Research Hospital Eye Clinic between 1992 and 1999. Of 48 charts identified, 19 met our inclusion criteria, having a record of brain tumor associated with sixth nerve palsy and 2 or more eye clinic visits at least 6 months apart. Children were considered recovered if they had an esotropia of less than 10 PD in primary gaze at the last follow-up visit and did not require surgical correction.

RESULTS

Of the 19 children included in the study, 10 were managed conservatively (no botulinum toxin or surgery for at least 6 months after diagnosis). Nine children received one or more botulinum toxin injections. Two (20%) of the 10 children in the conservatively managed group recovered without surgical intervention. Two (22%) of the 9 children in the botulinum toxin treatment group recovered without surgical intervention.

CONCLUSIONS

Treatment with botulinum toxin did not improve the rate of recovery in our series of children with brain tumors and sixth nerve palsies.

The role of drug treatment in children with strabismus and amblyopia

Strabismus, or misalignment of the eyes, is a common ophthalmic problem in childhood, affecting 2 to 5% of the preschool population. Amblyopia is an important cause of visual morbidity frequently associated with strabismus, and both conditions should be treated simultaneously. Pharmacological means for treating strabismus and amblyopia can be divided into 3 categories: paralytic agents (botulinum toxin) used directly on the extraocular muscles to affect eye movements; autonomic agents (atropine, miotics) used topically to manipulate the refractive status of the eye and thereby affect alignment, focus and amblyopia; and centrally acting agents, including levodopa and citicoline, which affect the central visual system abnormalities in amblyopia. Botulinum toxin, the paralytic agent that causes the clinical symptoms of botulism poisoning, can be injected in minute quantities to achieve controlled paralysis of the extraocular muscles. Although the role of botulinum toxin is established in adults with paralytic strabismus, its usefulness in the treatment of comitant childhood strabismus (primary esotropia and exotropia) is not universally accepted. Botulinum injections tend to be more effective with smaller degrees of strabismus, in patients with good binocular fusion, and in managing overcorrections or undercorrections after traditional muscle surgery. Inadvertent ptosis and paralysis of adjacent muscles, unpredictable responses and technical constraints of the injections limit its use in children. Miotic therapy, by altering the refractive state of the treated eye, offers an alternative to optical correction with bifocals in treating esotropia due to excessive accommodative convergence. It is also effective in treating residual esotropia following surgery. The ease of use of glasses restricts the wide application of miotics in these common strabismus syndromes. Atropine, an anticholinergic agent, paralyses the ability of the eye to focus or accommodate. In amblyopia therapy, atropine is used to blur vision in the non-amblyopic eye and offers a useful alternative to traditional occlusion therapy with patching, especially in older children who are not compliant with patching. The neurotransmitter precursor levodopa and the related compound citicoline have been demonstrated to improve vision in amblyopic eyes. The therapeutic role of these centrally acting agents in the clinical management of amblyopia remains unproven.

The natural history of acute traumatic sixth nerve palsy or paresis

BACKGROUND

Spontaneous resolution of traumatic sixth nerve palsy or paresis has been reported to range between 12% and 54%. However, previous studies have been based in tertiary referral centers, have been retrospective in nature, have included a heterogeneous group of patients, and have included patients with long-standing palsies. To provide a more accurate estimate of the true recovery rate, we performed a prospective natural history study.

METHODS

All members of the American Association for Pediatric Ophthalmology and Strabismus and the North American Neuro-Ophthalmology Society were invited to enroll patients with acute traumatic sixth nerve palsy or paresis between March 1996-February 1997. Recovery at 6 months after injury was defined as absence of diplopia in primary position and less than or equal to 10 PD distance esotropia in primary position. Patients who had been treated with botulinum toxin (n = 8) within 6 months after injury and patients with <6 months of follow-up (n = 3) were excluded.

RESULTS

Thirty-three eligible patients were enrolled by 27 investigators. Twenty-five (76%) of the palsies were unilateral and 8 (24%) were bilateral. The overall spontaneous recovery rate was higher than previously reported (73%, 95% CI 54%-87%). Spontaneous recovery was more frequent in unilateral cases (84%, 95% CI 64%-95%) than in bilateral cases (38%, CI 9%-76%; P = .02).

CONCLUSIONS

In this prospective multicenter study of acute traumatic sixth nerve palsy or paresis, the overall spontaneous recovery rate, particularly in unilateral cases, was much higher than previously reported. Our results have important sample size implications for the planning of any randomized treatment trial and may help guide early treatment decisions.

Botulinum toxin in fourth nerve palsies

BACKGROUND

Botulinum toxin A (BTXA) has not been used routinely in the management of fourth nerve (IV N) palsy. However, it is known that the results of surgery can be unpredictable with a risk of over- or under-correction.

METHODS

The results were reviewed of 20 patients, aged 19-70 years, with unilateral and bilateral IV N palsies who received BTXA injections to the inferior oblique or inferior rectus muscles. The aetiology was congenital in 12 (60%), traumatic in six (30%), due to myasthenia in one (5%), and unclear in one (5%). Fifty per cent of patients had had previous strabismus surgery to a maximum of four procedures. The mean pre-injection vertical deviation was 11 prism dioptres. All but two patients had a single injection. Average follow-up was 19 months.

RESULTS

Ten patients (group I) received BTXA as a primary therapy. Following inferior oblique injection, six patients received little benefit and went on to surgery (83%) or continued with prisms (17%). Five patients from group I who had inferior rectus toxin were discharged symptom-free. Group 2 (10 patients) received BTXA for residual deviations postoperatively; in this group all except one patient with no fusion achieved long-term benefit following inferior rectus BTXA. In those who had inferior oblique injections, BTXA was useful in one patient (25%). Inferior rectus injection produced a greater chance of temporary reversal of the deviation.

CONCLUSIONS

BTXA is of greatest benefit in patients with residual deviations particularly when the inferior rectus is injected, but is of limited value as a primary therapy in chronic IV N palsy.

Spontaneous recovery rate in traumatic sixth-nerve palsy

PURPOSE

To estimate the spontaneous recovery rate of isolated traumatic sixth-nerve palsy.

METHOD

A retrospective chart review over a 24-year period at a single institution, excluding patients who were first seen more than 6 weeks after injury, to reduce bias toward nonrecovery.

RESULTS

The Kaplan-Meier survival estimate of spontaneous recovery at 6 months was 27% (95% confidence interval [CI], 5% to 44%) in unilateral traumatic sixth-nerve palsy and 12% (95% CI, 0% to 33%) in bilateral traumatic sixth-nerve palsy.

CONCLUSION

Spontaneous recovery from isolated traumatic sixth-nerve palsy may be lower than previously reported. A prospective study is needed to provide a more accurate estimate of recovery rate.

Botulinum A exotoxin use in clinical dermatology

Botulinum toxin (BT) prevents the release of acetylcholine at the neuromuscular junction and produces reversible paralysis of striated muscle. This effect was initially used for ophthalmologic indications, particularly strabismus. The idea of using the toxin for purely cosmetic purposes arose from the observation that therapy for facial dystonias markedly decreased lines and wrinkles in the treated areas. The ease of application, high safety profile, and impressive results from the cosmetic use of BT have led to its rapid acceptance by many clinicians. As use of BT increases and its indications expand, an understanding of this therapeutic modality is timely. This article discusses the pharmacologic aspects of BT as well as the methods for administration as they relate to its cosmetic use.

Results of a prospective randomized trial of botulinum toxin therapy in acute unilateral sixth nerve palsy

Forty-seven patients entered a prospective randomized trial to assess the effect of early botulinum neurotoxin A treatment to the ipsilateral antagonist medial rectus on the ultimate recovery rate of acute unilateral sixth nerve palsy. Twenty-two patients received injections and 25 acted as controls. The overall etiologies were microvascular (72.3%), unknown (17%), multiple sclerosis (6%), and one case each of central nervous system (CNS) sarcoidosis and basilar artery ectasia. Eighty-three percent of the patients entered the trial within 2 weeks of the onset of symptoms and 95.7% within 3 weeks. The controls had a final recovery rate of 20/25 (80%), and the injected group had a final recovery rate of 19/22 (86%). No serious side effects were encountered. We conclude that there is no evidence for a prophylactic effect of botulinum toxin in the group that we have studied.

Modern management of sixth nerve palsy

Between November 1982 and September 1991, 179 patients with unilateral or bilateral sixth nerve palsy were treated in the Botulinum Toxin Strabismus Clinic at Moorfields Eye Hospital. Indications for treatment included prophylaxis (as part of a prospective treatment trial), maintenance therapy, diagnosis and adjunct to surgical therapy. A management plan for established sixth nerve palsy based on the rational use of toxin and surgery is suggested.

Treatment of unilateral acute sixth-nerve palsy with botulinum toxin

We studied 29 consecutive patients with acute unilateral sixth-nerve palsy, who received botulinum toxin injection to the antagonist medial rectus muscle. The average interval between onset of palsy and treatment was 40 days and the mean follow-up from the last injection was 14 months. Before treatment, esotropia in the primary position ranged from 12 to 45 prism diopters and limitation to abduction in the affected eye ranged from -2 (approximately 15 degrees lateral to midline) to -6 (15 degrees nasal to midline). After treatment, 22 of 29 patients (76%) had complete recovery of motility as determined by version testing. Of the seven patients with a residual abduction deficit, two had fusion in the primary position, three had fusion with prismatic correction, and two patients required subsequent surgery. Botulinum toxin injection seems to be an effective treatment option in cases of acute unilateral sixth-nerve palsy.

Botulinum A toxin (Oculinum) in ophthalmology

Botulinum A toxin has been used to treat strabismus and a variety of spasmodic neuromuscular diseases. Botulinum toxin treatment of strabismus is not as definitive and stable as the traditional surgical approach, but it has been found most useful in postoperative overcorrection, small deviations, sensory deviations, and acute sixth nerve palsy. This toxin has been effective in the treatment of essential blepharospasm and hemifacial spasm, for which it produces temporary relief of symptoms. In addition, this treatment has been applied to lower lid entropion, myokymia, aberrant regeneration of the seventh nerve, lid retraction, corneal exposure, nystagmus, spasmodic torticollis, and adductor spastic dysphonia.

Succinylcholine-stimulated muscle tensions following botulinum injection in the domestic cat

Succinylcholine (SCh) selectively stimulates, and can therefore selectively assay, the multiple innervated (MI) fiber system of the extraocular muscles. Since botulinum-A toxin has been observed to induce changes in eye position in humans, SCh was used to assess the effect of botulinum-A on the SCh-sensitive MI fibers of extraocular muscles. Intravenous SCh infusion (40 micrograms-1 kg-1 min-1 was performed in the anesthetized domestic cat. Thirty-eight infusions were performed in 19 normal controls, measuring the peak tensions generated in the four horizontal and four vertical rectus muscles. Succinylcholine-stimulated muscle tensions (SSMT) were then repeated in nine animals, 4 weeks and 10 weeks following injection of botulinum-A toxin into both medial rectus muscles. Mean peak SSMTs were unchanged at 4 and 10 weeks following botulinum injection when compared to controls. We propose that botulinum chemo-denervation has no acute or chronic effect on the MI SCh-sensitive muscle fibers of the medial recti of the domestic cat. This lack of effect on the postsynaptic MI fibers indirectly supports light and electron microscopic studies which show changes predominantly in the singly innervated (SI), rather than the MI fibers following botulinum injection. Mean peak SSMTs were also greater for medial and superior rectus muscles compared to lateral and inferior recti respectively, suggesting a greater number or proportion of MI fibers in medial and superior recti.

Early botulinum toxin treatment of acute sixth nerve palsy

Eight patients with total sixth nerve palsy were treated with botulinum toxin injection to the antagonist non-paretic medical rectus, within eight weeks of the onset of the palsy. Within a few days seven of the eight gained fusion without the necessity of a marked head turn, and none complained of confusing reversal of diplopia. The same seven recovered full function. The mean follow-up period after the last injection was 20 months. Seven palsies were the result of head trauma and one was due to cerebro-vascular disease. This preliminary report suggests that early botulinum toxin injection of patients with recent onset sixth nerve palsy is beneficial. Although all of the patients may possibly have recovered full lateral rectus function without treatment, the aetiologies of their palsies were of the type that frequently do no resolve. A randomised double-blind study is necessary more precisely to determine the effectiveness of this form of therapy.

Early and late botulinum toxin treatment of acute sixth nerve palsy

Ten patients with sixth nerve palsy were treated with botulinum toxin injection to the antagonist nonparetic medial rectus. All patients were followed for a minimum of 14 months after the last injection. Six patients were treated within eight weeks of the onset of the palsy. Within a few days five of the six gained fusion, without the necessity of a marked head turn and none complained of confusing reversal of diplopia. The same five recovered full function. Four patients with no medial rectus contracture on forced duction testing were treated six months or longer after the onset of the palsy and none recovered full function. One of the four patients was permanently over-corrected despite persistent weakness of the lateral rectus. This preliminary report suggests that early botulinum toxin injection of patients with recent onset (acute) sixth nerve palsy is beneficial. Since some patients may recover spontaneously a randomised double-blind study is necessary to more precisely determine the effectiveness of this form of therapy. Botulinum toxin does not appear to be effective in facilitating recovery in those cases with poor lateral rectus function six months or longer after the onset of the palsy, even when there is no contracture of the medial rectus.