Quantitative eye movement recordings in a patient with acquired bilateral superior oblique palsy before and after a bilateral Harada-Ito procedure

PURPOSE

We examined the effects of the Harada-Ito procedure on static and dynamic alignment in an adult with acquired bilateral superior oblique palsy (SOP).

METHODS

3D eye movements were recorded before and six weeks after a bilateral Harada-Ito procedure. Superior oblique muscle (SOM) size and contractility were assessed with orbital imaging.

RESULTS

On MRI, the left SOM was smaller than the right. Little contractile thickening was present in down gaze for either eye. Preoperatively, the patient had a hypertropia: 1.9 degrees right hypertropia (at down 20 degrees , left 20 degrees ) and 6.4 degrees left hypertropia (at down 20 degrees , right 20 degrees ). Postoperatively, the vertical tropia in all positions was < 1 degrees . Listing's primary position rotated toward straight ahead for the RE but was unchanged for the LE. Postoperatively, for 40 degrees upward saccades peak dynamic intrasaccadic extorsion decreased by 2.2-3.2 degrees for both eyes and for 40 degrees downward saccades by 2.3-3.6 degrees for the RE but was unchanged for the LE. Saccade conjugacy improved and post-saccadic drift lessened for all vertical saccades.

CONCLUSIONS

The Harada-Ito procedure produced striking improvements in static and dynamic alignment in bilateral SOP. Some changes were binocular (decreased post-saccadic drift, improved saccade conjugacy, less dynamic extorsion for upward saccades) but others were much greater in the less paretic eye (torsional gradients from up to down gaze, less dynamic extorsion for downward saccades). Both central adaptive and peripheral mechanical changes explain these findings. Our results also imply that the Harada-Ito procedure has more effect when there is residual function of the SOM.

Paralytic strabismus

In the last year, published works on paralytic strabismus have concerned many topics. New advances have been made in the knowledge of epidemiology of ocular nerve palsies in children, muscular causes of paralytic strabismus, and neuroimaging management of patients with third nerve palsy who are at risk of cerebral aneurysms. The author describes reports on rare associations of oculomotor imbalances and neurologic diseases as well as atypical orbital localizations of tumors. He also discuss new neuroimaging findings in congenital superior oblique muscle palsy and new acquisitions on cyclofusion deterioration in acquired trochlear palsy.

[Myokymia of the obliquus superior muscle and cryptogenetic epilepsy]

BACKGROUND

Myokymia of the obliquus superior muscle is a rare episodic microtremor caused by uncontrolled activities of the trochlearis nerve fibres. Epilepsy is also caused by spontaneous discharges of neurons. In our report we present an associated epilepsy which to the best of our knowledge is described for the first time.

PATIENT

An 61-year old man with twitches of the right eye for 6 weeks and a subjective feeling of eye movement was investigated at our hospital. His history was void of any ophthalmologic diseases. However, he suffered from cryptogenetic epilepsy known since childhood. The morphological and orthoptical findings of his eyes were normal. During the slit-lamp investigation a unilateral rotating microtremor of the right eye induced by looking downward was seen. The neurologic investigation, magnetic resonance imaging and assessment of the thyreoid function did not show further pathological results. The patient underwent treatment with carbamazepine. Under this therapy he did not show any symptoms of myokymia during follow-up.

SUMMARY

To the best of our knowledge this is the first case of myokymia of the obliquus superior muscle associated to epilepsy. To our opinion, any case of this syndrome should be investigated for epilepsy. A causal relation is unlikely since the most probable etiologies are either spontaneous discharges of trochlear nucleus neurons or a close contact between vessel and nerve analogously to trigeminal neuralgia.

[Vertical vergence adaptation in cases of superior oblique palsy]

PURPOSE

To investigate the characteristics of vertical adaptation (VA) in superior oblique muscle palsy (SOP).

SUBJECTS AND METHODS

VA was examined in 15 patients with unilateral congenital SOP, 7 patients with unilateral acquired SOP, and 35 normal volunteers. An adaptive change in the fusion-free ocular alignment, VA, was measured with a computer-aided mirror haploscope. The fusion-free ocular alignment was measured before inserting a 3 prismdiopter vertical prism, immediately after inserting the prism, and at 10 minutes and 30 minutes after insertion. We investigated VA gain, age, vertical fusional range, response of prism adaptation test (PAT), and superior oblique muscle atrophy in magnetic resonance imaging (MRI).

RESULTS

The VA gain (mean +/- standard deviation, %) at 30 minutes in congenital, acquired, and normal groups was 86 +/- 53, 34 +/- 23 and 58 +/- 16, respectively. The mean of the VA gains at 30 minutes in the congenital group was greatest, and that in the acquired group was least(p < 0.01). In the congenital group there was a correlation between VA gain and response of PAT (p = 0.02, r = 0.60). The VA gain did not significantly correlate with age, vertical fusional range, or muscle atrophy.

CONCLUSION

The VA gain observed in congenital SOP was greater than that of acquired SOP, and affected the response of PAT.

Superior oblique muscle MRI asymmetry and vertical deviation in patients with unilateral superior oblique palsy

PURPOSE

To evaluate the MRI cross sectional greater area of the unilateral superior oblique (SO) muscle in patients with congenital or acquired superior oblique palsy to detect asymmetries and to determine if there is any relationship between the degree of vertical deviation and the muscle size determined by imaging.

METHODS

Magnetic Resonance Imaging coronal images were obtained in primary position, supraversion and infraversion. Interocular differences and intergroup differences were compared in 17 patients with unilateral acquired or congenital SO palsy and 15 orthotropic control subjects.

RESULTS

Mean maximal difference was 3.56 +/-0.83 mm(2) (p 0.01) between healthy and paretic eye in the paretic group, and 1.08 +/-0.40 mm(2) (p 0.02) in the control group. Statistical Intergroup comparison was p 0.02 (conventionally statistically significant). In 9 patients the maximal interocular difference was detected in 44.4% in infraversion, 33.3% indistinctly in supra- and infraversion and 22.2% in primary position. The correlation coefficient between vertical deviation and interocular asymmetry was not conventionally statistically significant at p>0.05.

CONCLUSIONS

Patients with unilateral superior oblique palsy showed significant MRI asymmetry, which was represented by a relatively greater healthy SO muscle size, in the paretic congenital group. We found no association between the SO muscle size and the degree of any vertical deviation present.

Clinical characteristics and surgical outcomes in patients with superior oblique muscle palsy: a retrospective study on 1057 patients

BACKGROUND

To evaluate the clinical findings of patients with SOP who underwent surgery.

METHODS

This historical cohort study was performed on 1057 SOP patients managed with surgery in Farabi Hospital, Iran, from 2011 to 2022.

RESULTS

There were 990 (93.7%) patients with unilateral SOP with the mean age of 21.8 ± 14.8 years. Of these, 715 patients (72.2%) were diagnosed with congenital SOP, and 275 patients (27.8%) had acquired SOP (P < 0.001). In contrast, 67 (6.3%) patients were diagnosed with bilateral SOP, with the mean age of 19.4 ± 15.6 years. Among these, 18 cases exhibited the masked type. The mean angle of vertical deviation in primary position at far in unilateral and bilateral cases was 15.6 ± 8.3 and 13.3 ± 9.1 △, respectively (P < 0.001). In unilateral cases, abnormal head posture (AHP) was detected in 847 (85.5%) patients and 12 (1.2%) had paradoxical AHP. Amblyopia was found in 89 (9.9%) unilateral and 7 (10.3%) bilateral cases. Solitary inferior oblique myectomy, was the most common surgery in both unilateral (n = 756, 77.1%) and bilateral (n = 35, 52.2%) patients. The second surgery was performed for 84 (8.6%) unilateral and 33 (49.3%) bilateral cases (P < 0.001). The prevalence of amblyopia and the mean angle of horizontal deviation were significantly higher in patients who needed more than one surgery (all P < 0.05).

CONCLUSION

Congenital SOP was more than twice as frequent as acquired SOP and about 90% of unilateral and 50% of bilateral cases were managed with one surgery. Amblyopia and significant horizontal deviation were the most important factors for reoperation.

TRIAL REGISTRATION

The Institutional Review Board approval was obtained from the Tehran University of Medical Sciences (IR.TUMS.FNM.REC.1400.012) and this study adhered to the tenets of the Declaration of Helsinki and HIPAA.

Bilateral Congenital Trochlear-Oculomotor Synkinesis in a 5-Month-Old Infant

Oculomotor synkinesis is an unusual phenomenon that encompasses various presentations with few associations reported in the literature. It can occur with or without a previous setting of oculomotor nerve injury. The authors present the first reported case of bilateral congenital trochlear-oculomotor synkinesis in a 5-month-old infant. [J Pediatr Ophthalmol Strabismus. 2024;61(5):e50-e53.].

Incomitance of ocular rotation axes in trochlear nerve palsy

Strabismus due to palsy of a single muscle in one eye is always incomitant, which is a consequence of Hering's law of equal innervation. We asked whether this law had similar consequences on the orientation of ocular rotation axes. Patients with unilateral trochlear nerve palsy were oscillated about the nasooccipital (= roll) axis (+/-35 degrees, 0.3 Hz), and monocularly fixed on targets on a head-fixed Hess screen. Both the covered and uncovered eyes were measured with dual search coils. The rotation axis of the covered eye (paretic or healthy) tilted more nasally from the line of sight when gaze was directed toward the side of the healthy eye. The rotation axis of the viewing eye (paretic or healthy), however, remained roughly aligned with the line of sight. We conclude that incomitance due to eye muscle palsy extends to ocular rotation axes during vestibular stimulation.

Effect of graded partial inferior rectus muscle tenotomy in treatment for superior oblique paralysis

PURPOSE

To evaluate the surgical outcomes for patients with superior oblique paralysis (SOP) who underwent the inferior oblique weakening and the graded partial inferior rectus muscle tenotomy in the contralateral eye.

METHODS

Medical records were retrospectively reviewed for those SOP patients who had hyperdeviation of 4 △ -20 △ in the primary position and 8 △ -25 △ in the downgaze position. Patients were subdivided into three subgroups according to their vertical deviation angle in the downgaze position. They underwent an ipsilateral inferior oblique muscle recession and a graded partial tenotomy of the contralateral inferior rectus muscle. The vertical deviation angles, abnormal head position, and fundus torsion were compared statistically before and after operations. All patients were followed up at least 1 year.

RESULTS

Forty-seven patients were included in this study. The mean follow-up period was 17.2 months after surgery (ranging from 12 to 28 months). The vertical deviation angle was averaged preoperatively to 7.74 △ ± 3.23 △ in the primary position and 15.30 △ ± 5.92 △ in the downgaze position and reduced postoperatively to 0.85 △ ± 1.15 △ in the primary position and 1.53 △ ± 1.49 △ in the downgaze position ( P < 0.001). All patients had an abnormal head position preoperatively and had improved significantly postoperatively. Fundus extorsion had been improved significantly postoperatively.

CONCLUSION

The surgical procedure of IO weakening combined with contralateral graded partial inferior rectus muscle tenotomy is a successful intervention for the correction of small deviation in primary position of SOP.

Analysis of the effect of congenital unilateral trochlear nerve paresis on retinal vascular density: a retrospective study

PURPOSE

To use swept-source optical coherence tomography angiography (SS-OCTA) to investigate the alterations in retinal vascular density (VD) in patients presenting with congenital unilateral trochlear nerve palsy.

METHODS

The medical records of patients diagnosed with congenital unilateral trochlear nerve palsy and those of a healthy control group were reviewed retrospectively. Comprehensive ocular examinations and SS-OCTA imaging were conducted. The study population was divided into three subgroups of eyes: paretic eyes, fellow eyes, and controls. All participants underwent comprehensive ophthalmic examinations, which included assessments of ocular motility, cycloplegic refraction, and axial length measurement. Various strabismus tests-the cover-uncover test, prism and alternate cover test, Krimsky test, and Parks-Bielschowsky test-were conducted to confirm the diagnosis and evaluate the extent of the condition.

RESULTS

A total of 34 patients and 39 healthy controls were included. Sex and age distributions were similar between groups. Significant differences were observed in central VD of the superficial capillary plexus (SCP) and deep capillary plexus (DCP) between paretic eyes, fellow eyes, and control eyes. The fellow eye exhibited lower central VD compared to the paretic and control eyes. Inverse correlations between deviation angle and VD were noted in different SCP and DCP quadrants in paretic eyes.

CONCLUSIONS

In our study cohort, there were significant changes in retinal VD in fellow eyes of patients with trochlear nerve palsy, which we speculate may be related to compensatory head position.

Adaptive neural mechanism for listing's law revealed in patients with fourth nerve palsy

PURPOSE

During fixation and saccades, human eye movements obey Listing's law, which specifies the eye's torsional angle as a function of its horizontal and vertical position. Torsion of the eye is in part controlled by the fourth nerve. This study investigates whether the brain adapts to defective torsional control after fourth nerve palsy.

METHODS

Thirteen patients with fourth nerve palsy (11 chronic, 2 acute), and 10 normal subjects were studied with scleral search coils. With the head immobile, subjects made saccades to a target that moved between straight ahead and eight eccentric positions. At each target position, fixation was maintained for 3 seconds before the next saccade. From the eye position data, we computed the plane of best fit, referred to as Listing's plane. Violations of Listing's law were quantified by computing the "thickness" of this plane, defined as the SD of the distances to the plane from the data points.

RESULTS

Both the paretic and nonparetic eyes in patients with chronic fourth nerve palsy obeyed Listing's law during fixation and saccades. However, Listing's planes in both eyes had abnormal orientations, being rotated temporally, meaning the eye excyclotorted during downgaze and incyclotorted during upgaze. In contrast, the paretic eye of patients with acute fourth nerve palsy violated Listing's law during saccades. During downward saccades, transient torsional deviations moved the paretic eye out of Listing's plane. Torsional drifts returned the paretic eye to Listing's plane during subsequent fixation.

CONCLUSIONS

During saccades, acute fourth nerve palsy violates Listing's law, whereas chronic palsy obeys it, indicating that neural adaptation can restore Listing's law by adjusting the innervations to the remaining extraocular muscles, even when one eye muscle remains paretic. The transient torsional deviations during downward saccades in acute palsy are attributed to pulse-step mismatch, as a result of lesions in the trochlear nerve that lead to an imbalance of phasic and tonic signals reaching the muscles.

Use of a Microelectromechanical Systems Sensor for Objective Measurements of Abnormal Head Posture in Congenital Superior Oblique Palsy Patients

Purpose

The purpose of this study was to design an objective method for measurement of head positions as achieved with use of a microelectromechanical systems (MEMS) sensor. In addition, to use this system to observe the abnormal head position (AHP) in patients with congenital superior oblique palsy (SOP) before and after their surgery.

Methods

An MEMS sensor was designed for recording of the pitch, roll, and yaw values of the head position in real time. The MEMS sensor was then fixed on the synoptophore from -30 degrees to +30 degrees positions horizontally and vertically to test the accuracy of these measurements. Then, we tested 13 participants with AHP using the MEMS method and the photographic method and compared their correlations. Finally, the pitch, roll, and yaw values of head positions were measured using this MEMS sensor in 31 patients with congenital SOP as performed before and after their surgery.

Results

The MEMS sensor (LPMS-B2; Alubi, Guangzhou, China; 400 hertz [Hz]), as based on the theory of a gyroscope, was designed and connected to a smartphone via Bluetooth. It was able to conveniently record the patient's pitch, roll, and yaw head positions in real time, recordings which were consistent with the scales of the synoptophore (P > 0.05) and good correlations with the photographic method (P < 0.001). The main preoperative AHP in patients with SOP was roll (22/31, 71%). Pre- and postoperative vertical deviations were 16.4 ± 7.3 prism diopters (PD) and 4.1 ± 4.2 PD, respectively (P = 0.001). The AHP in patients with SOP was positively correlated with the angle of extorsion in the dominant eye (P = 0.01), rather than that of the vertical deviation.

Conclusions

The MEMS sensor described in this report is a simple, practical, and accurate objective device for use in head position measurements. In patients with SOP, the AHP is related to the angle of extorsion in the dominant eye.

Translational Relevance

The MEMS sensor was designed as a micro-wireless dynamic high-precision device for AHP measurement, which has the potential for use in a clinic.

Recovery of Third, Fourth, and Sixth Cranial Nerve Palsies in Pituitary Adenoma and Meningioma Patients

BACKGROUND

This retrospective, observational cohort study aimed to determine recovery rate and recovery time of ocular motor nerve palsies (OMP) of third (CN III), fourth (CN IV), or sixth cranial nerves (CN VI)-and associated prognostic factors-in meningioma and pituitary adenoma (PA) patients.

METHODS

A total of 25 meningioma (28 eyes) and 33 PA patients (36 eyes), treated at the Leiden University Medical Center in the Netherlands from January 1, 1978 to January 31, 2021, were included. OMPs were evaluated according to a newly created recovery scale using on-clinical and orthoptic examinations, which were performed every 3-4 months until palsy recovery, or at 18 months follow-up.

RESULTS

Recovery rates of CN III (meningioma 23.5% vs PA 92.3%), CN IV (meningioma 20% vs PA 100%), and CN VI (meningioma 60% vs PA 100%) palsies were observed at 18 months follow-up, with differences between the 2 tumor types being observed in the treated patients only. Median recovery time of all OMPs combined was significantly longer in meningioma patients (37.9 ± 14.3 months vs 3.3 ± 0.1 months; P < 0.001). No significant protective or risk factors for recovery rate or time were identified.

CONCLUSIONS

OMP recovery rates in treated patients were more favorable in patients with PA compared with patients with meningiomas, independent of OMP cause. With these new insights in OMP recovery, more accurate prognoses and appropriate follow-up strategies can be determined for meningioma and PA patients with OMPs.

Surgical treatment of unilateral acquired superior oblique muscle palsy in adults by inferior oblique belly transposition: a retrospective analysis

PURPOSE

Evaluate and analyze the efficacy of inferior oblique belly transposition (IOBT) in treating adult patients with diplopia and small-angle hypertropia caused by mild to moderate inferior oblique overaction (IOOA) secondary to acquired superior oblique palsy (SOP).

METHODS

Nine adult patients with diplopia and small-angle hypertropia associated with mild to moderate IOOA secondary to unilateral acquired SOP were included in the current retrospective study. All patients received the IOBT procedure between February 2019 and May 2023 at The Second People's Hospital of Jinan and were followed up for more than 6 months after the surgery. During the procedure, the belly of the inferior oblique muscle was fixed to the sclera at 5 mm posterior to the temporal insertion of the inferior rectus muscle. The following indicators were reviewed pre- and post-surgery: the vertical deviation (VD) in the primary position and in the Bielschowsky test, the fovea disc angle (FDA) of the affected eye, changes in IOOA, and diplopia.

RESULTS

After IOBT, the VD in the primary position decreased from 7.22△ ± 1.72△ (range 4△-10△) to 1.22△ ± 1.30△ (range 0△-3△). The VD in the Bielschowsky test decreased from 13.00△ ± 1.80△ to 3.22△ ± 1.09△. The FDA decreased from 10.02° ± 3.34° to 6.26° ± 1.91°. The grade of IOOA was reduced from 2.00 (1.00, 2.00) to 0.00 (0.00, 1.00). All changes were statistically significant (P < 0.001 or P = 0.006). Diplopia was resolved completely for all patients.

CONCLUSIONS

IOBT can effectively treat adults with diplopia and small-angle hypertropia caused by mild to moderate IOOA secondary to acquired SOP.

Small tuck for superior oblique palsy

PURPOSE

To investigate the surgical outcomes of small superior oblique (SO) tuck-denoting minimal tendon laxity-in patients with unilateral SO palsy.

METHODS

The medical records of consecutive patients treated with ≤6 mm SO tuck from 2000 to 2018 at Kellogg Eye Center, University of Michigan, were reviewed retrospectively. Tendon tucks were performed to a fairly uniform tension in an amount that just eliminated slack in the tendon. Pre- and postoperative motility measurements were compared. Patients were excluded if they had a history of prior strabismus surgery or concurrent vertical rectus or inferior oblique surgery.

RESULTS

A total of 27 cases (14 males) met inclusion criteria. The median age at surgery was 47 years (range 3-74 years). The mean SO tuck (total, both arms of tuck) was 4.9 mm (range, 2-6 mm). After surgery, median hypertropia decreased from 9Δ to 1Δ in primary position and from 20Δ to 4Δ in the SO field of action (contralateral downgaze). Lateral incomitance (difference in hypertropia between contralateral and ipsilateral gaze) decreased from 10Δ to 2Δ (P < 0.001 in each case). Six patients had diplopia in upgaze postoperatively that was not symptomatic enough to require reoperation. Six patients had residual hypertropia requiring additional surgery.

CONCLUSIONS

Small SO tuck provided disproportionate correction of hypertropia in the SO field of action and nearly eliminated lateral incomitance without producing unacceptable iatrogenic Brown syndrome. Even in the absence of tendon laxity, SO tuck was a good surgical option for SO palsy in our cohort where there was marked lateral incomitance and the greatest deviation was in the SO field of action.

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.].