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.

Residual symptomatic superior oblique palsy

PURPOSE

To determine the outcome of patients treated for residual symptomatic hyperdeviations, in a tertiary referral centre, following a previous weakening procedure of the ipsilateral Inferior Oblique (IO) muscle in Superior Oblique (SO) palsy.

METHODS

A retrospective review of 37 patients seen over 6 years at one institution who had remained symptomatic from a SO palsy despite having had an initial weakening procedure to their ipsilateral IO (myectomy or recession). Median age was 19 years (range 3 to 56 years). Information recorded included pre- and postoperative deviation and ocular motility findings, preoperative symptoms, findings at the time of surgery, and outcome.

RESULTS

Nine patients underwent repeat weakening surgery (disinsertion) on the ipsilateral IO only. Thirteen patients underwent strengthening surgery on the ipsilateral SO only. Nine patients had surgery on both the ipsilateral IO and SO. Six patients had surgery on the ipsilateral IO with either horizontal or vertical rectus surgery. Nine (24%) patients remained symptomatic after their initial procedure and are regarded as initial failures. Four of these patients had masked bilateral IO weakness. Five patients required additional surgery. At final outcome, 84% were discharged with resolution of their symptoms.

CONCLUSIONS

In the light of these findings we suggest an approach for the management of these patients. This should always include exploring a previously operated ipsilateral IO. Despite this, patients should be warned that they have a 1 in 4 chance of needing further surgery to achieve adequate ocular motility.

Torsion in patients with superior oblique palsies: dynamic torsion during saccades and changes in Listing's plane

BACKGROUND

The purpose was to assess intra- and post-saccadic torsion in superior oblique palsy (SOP) patients and the effect of surgery on torsion.

METHODS

Eleven patients with a presumed congenital SOP and five with acquired SOP performed 10 degrees vertical saccades over a range of +/-20 degrees. Eye movements were recorded with dual search coils. Dynamic torsion was calculated by subtracting the expected change in torsion during the saccade (based upon static torsion before and after the saccade) from the maximum intrasaccadic torsion. Eight healthy subjects were controls. We also examined the effects of surgery on dynamic torsion and the orientation of Listing's plane in patients with congenital SOP who were operated on either by weakening of the inferior oblique muscle on the affected eye (n=5), by recession of the inferior rectus muscle on the normal eye (n=4) or by both procedures (n=2). Postoperative recordings were obtained at least 1 month after surgery.

RESULTS

Patients with congenital and acquired SOP showed an increased dynamic extorsion, primarily during downward saccades. Following a recession of the inferior oblique muscle in congenital SOP patients, half showed significant decreases in extorsion (up to 1.0 degrees) during downward saccades by the affected eye. Following surgery all showed a temporal rotation of Listing's plane (up to 15 degrees for primary position).

CONCLUSION

Patients with a SOP show a characteristic pattern of dynamic torsion during vertical saccades differing from normals. Recession of the inferior oblique muscle leads to rotation of Listing's plane in all congenital SOP patients and causes large changes in dynamic torsion in a subgroup of them, perhaps reflecting the heterogeneity of congenital SOP.

Acute superior oblique palsy in monkeys: II. Changes in dynamic properties during vertical saccades

PURPOSE

To investigate vertical and torsional eye motion during and immediately after vertical saccades with acute acquired superior oblique palsy (SOP) in monkeys.

METHODS

The trochlear nerve was severed intracranially in two rhesus monkeys. After surgery, the paretic eye was patched for 6 to 9 days, and then binocular viewing was allowed. Three-axis eye movements (horizontal, vertical, and torsion) were measured with binocular, dual search coils. Eye movements were recorded before surgery and then beginning 2 to 3 days after surgery during 20 degrees vertical saccades over a +/-20 degrees horizontal and vertical range.

RESULTS

The main findings were: (1) Saccade amplitude in the paretic eye (PE) was smaller than that of the normal eye (NE), especially for downward saccades with the PE in adduction; (2) vertical drift was backward after upward saccades with the PE in adduction or abduction, onward after downward saccades with the PE in adduction, but backward for downward saccades with the PE in abduction, drift time constants averaged 35 ms; (3) peak dynamic blip intrasaccadic torsion increased (relative extorsion), the most for upward saccades with the PE in abduction; (4) postsaccadic torsional drift increased (relative intorsion), the most for downward saccades with the PE in adduction; and (5) the peak velocity-amplitude relationship in vertical saccades was little affected, but the ratio between the peak velocity of the two eyes was a consistent indicator of the palsy.

CONCLUSIONS

Rhesus monkeys with acute acquired SOP show characteristic changes in vertical and torsional movements during and immediately after vertical saccades that help define the ocular motor signature of denervation of the SO muscle. These dynamic changes were largely unrelated to the changes in static alignment over time, suggesting that static and dynamic disturbances in SOP are influenced by separate central mechanisms.

Acute superior oblique palsy in monkeys: I. Changes in static eye alignment

PURPOSE

To investigate immediate and long-term changes in static ocular alignment with acute acquired superior oblique palsy (SOP) in monkeys.

METHODS

The trochlear nerve was severed intracranially in two rhesus monkeys. After the surgery, the paretic eye was patched for 6 to 9 days, and then binocular viewing was allowed. Three-axis eye movements (horizontal, vertical, and torsional) were measured with binocular, dual search coils. Eye movements were recorded over a +/-20 degrees horizontal and vertical range of fixations before the lesion and then, beginning the first day after surgery. Changes in alignment with +/-30 degrees head tilt were also studied.

RESULTS

The main findings were (1) misalignment (10-12 degrees vertical in adduction, down; 10-12 degrees torsional in abduction, down); (2) changes in vertical deviation (VD) with head tilt (Delta 2-6 degrees with left versus right 30 degrees tilt); and (3) changes in comitance and VD over time. During the early postlesion period, before binocular viewing was allowed, VD decreased and comitance improved. Once binocular viewing was allowed, VD increased and comitance worsened.

CONCLUSIONS

Rhesus monkeys with induced SOP show a characteristic pattern of misalignment that helps define the ocular motor signature of acute denervation of the superior oblique muscle. The animals also showed striking changes over time in the amount and comitance of the vertical misalignment that depended on whether viewing was monocular or binocular, suggesting a role for proprioception in adaptation to misalignment with habitual monocular viewing.

Acute superior oblique palsy in monkeys: III. Relationship to Listing's Law

PURPOSE

To investigate the three-dimensional orientation of the eye and its relationship to Listing's Law in monkeys with acute acquired superior oblique palsy (SOP).

METHODS

The trochlear nerve was severed intracranially in two rhesus monkeys. Three-axis eye movements (horizontal, vertical, and torsion) were measured with binocular, dual search coils during fixation of targets in a 40 degrees x 40 degrees grid. Rotation vectors were calculated, and Listing's plane (LP) was determined by a least-squares planar fit of eye torsion as a function of horizontal and vertical position.

RESULTS

The main findings were: (1) In the paretic eye, there was an immediate and sustained rotation of the orientation plane by approximately 25 degrees in the temporal direction; (2) the thickness of LP, defined as the torsional standard deviation (SD), increased little (by 0.13 degrees in M1 and 0.08 degrees in M2) after SOP, and (3) the SD of intrasaccadic torsion was slightly greater than that during fixation, but there was no change after SOP.

CONCLUSIONS

Acute SOP in rhesus monkeys leads to a temporal rotation of LP. This is consistent with a relatively increased extorsion in down gaze due to a loss of normal intorsion by the superior oblique muscle. The SD of torsion increased by only a small amount, implying that the validity of Listing's Law is not affected much by complete SOP, despite the large change in the orientation of LP.

Clinical features and natural history of acquired third, fourth, and sixth cranial nerve palsy

PURPOSE

Clinical features of acquired third, fourth, and sixth cranial nerve palsy showed variation among previous studies. Evaluation of natural course with objective criteria will establish accurate recovery rates and important factors for recovery.

METHODS

Retrospective chart review was performed on 206 patients who visited a neuro-ophthalmic department with acquired third, fourth, and sixth nerve palsy. Aetiology and results of ocular exam on each visit were reviewed, and multivariate logistic regression analysis was performed to identify independent factors affecting recovery.

RESULTS

The sixth cranial nerve was affected most frequently (n=108, 52.4%) and vascular disease (n=64, 31.1%) was the most common aetiology. Recovery was evaluated with change of deviation angle for 108 patients, who were first examined within a month of onset and followed up for at least 6 months. Ninety-two (85.2%) patients showed overall (at least partial) recovery and 73 (67.6%) showed complete recovery. In univariate analysis, initial deviation angle was found to be only significant factor associated with complete recovery (P=0.007) and most patients who experienced successful management of treatable underlying disease showed recovery.

CONCLUSIONS

With objective criteria based on deviation angle, overall recovery rate from the third, fourth, and sixth nerve palsy was 85.2%. Patients who had smaller initial eyeball deviation or successful management of treatable underlying disease had a high chance of recovery.

Temporary incyclotorsion following surgical correction of bilateral superior oblique palsy

We report three patients with acquired bilateral superior oblique paresis who had bilateral modified Harada-Ito procedures, which resulted in significant incyclotorsion (ranging from 6 degrees to 19 degrees ) on the first day postoperatively. For Case 1 this was the only procedure, while Cases 2 and 3 also underwent simultaneous bilateral inferior oblique weakening. This overcorrection decreased spontaneously over the following 8 months to leave all patients asymptomatic. One patient returned 8 years following the initial surgery with symptoms of diplopia and recurrence of excyclotorsion.

Efficacy of the Lancaster Red–Green Test for the Diagnosis of Superior Oblique Palsy

PURPOSE

The purpose of this study was to evaluate the usefulness of the Lancaster red-green test (LRGT) in patients with superior oblique palsy (SOP).

METHODS

The LRGT results of 42 adult patients with unilateral SOP (33 patients) or bilateral SOP (nine patients) were evaluated and compared with those of 21 patients who showed cyclotropia on Lancaster red-green test but did not have SOP (the non-SOP group). The degree of cyclotropia in primary position and downgaze, horizontal and vertical deviation, V pattern, and the presence of alternating hypertropia or reversal of hypertropia in the oblique field of gaze were analyzed using computer imaging software.

RESULTS

The SOP groups showed a larger cyclotropia difference between primary position and downgaze than the non-SOP group. The bilateral SOP group showed a significantly larger degree of cyclotropia in the primary position and downgaze and a smaller amount of vertical deviation in the primary position than the unilateral SOP group. Four of nine patients with bilateral SOP and none of 33 patients with unilateral SOP showed an alternating hypertropia and reversal of hypertropia in the oblique field.

CONCLUSIONS

The LRGT was found to be useful for the diagnosis of SOP and for the differentiation of unilateral SOP and bilateral SOP.

Static Otolith-ocular Reflex Reflects Superior Oblique Muscle Disorder

PURPOSE

To elucidate the action of static otolith-ocular reflex (sOOR) in patients with superior oblique palsy (SOP).

DESIGN

Observational case series study.

METHODS

Compensatory ocular countertorsion produced by sOOR was analyzed in 12 patients with unilateral SOP and 11 normal subjects using a head-mounted measuring system.

RESULTS

When the head was tilted laterally to the ipsilateral side, the mean ratio (%) of compensatory countertorsion of the paretic eye in SOP patients to the head-tilt angle was significantly decreased compared with that in normal subjects (7 +/- 6% for patients and 17 +/- 4% for normal subjects, P < .05). Mean ratio of compensatory countertorsion of the paretic eye in nine patients with superior oblique (SO) muscle atrophy was significantly lower than that in three patients with nonatrophy on tilting to the ipsilateral shoulder (6 +/- 3% for patients with atrophy and 14 +/- 6% for patients with nonatrophy, P < .05).

CONCLUSIONS

sOOR reflects the anatomic disorder of the superior oblique muscle in SOP.

Comparison of Harms tangent screen and search coil recordings in patients with trochlear nerve palsy

Harms tangent screen, a subjective measurement method of three-dimensional binocular alignment, was compared with search coil recording. Twenty-three patients with unilateral trochlear nerve palsy were measured in nine gaze positions. The two methods correlated best for the horizontal gaze deviation, the vertical gaze deviation, and the vertical incomitance, but there was no correlation for the results of torsional incomitance. Using Harms tangent screen, torsional deviation underestimated the torsional incomitance measured by the search coils. Therefore, central torsional fusional mechanisms or alignment error in the Harms tangent screen are assumed.

Adaptations and Deficits in the Vestibulo-Ocular Reflex after Peripheral Ocular Motor Palsies

Palsy of a nerve might be expected to lower vestibulo-ocular reflex (VOR) responses in its fields of motion, but effects of peripheral neuromuscular disease were unknown. We recorded the VOR during sinusoidal head rotations in yaw, pitch, and roll at 0.5-2 Hz and static torsional gain in 43 patients with unilateral nerve palsies. Sixth nerve palsy (n = 21) reduced both abduction and adduction VOR gains in darkness. In light, horizontal visually enhanced VOR (VVOR) gains were normal in moderate and mild palsy. In severe palsy, horizontal VVOR gains remained low in the paretic eye when it was fixating, whereas gains in the nonparetic eye became higher than normal. Third nerve palsy (n = 10) decreased VOR and VVOR gains during abduction, adduction, elevation, depression, extorsion, and intorsion. Fourth nerve palsy (n = 13) reduced VOR gains of the paretic eye during intorsion, extorsion, elevation, depression, abduction, and adduction, but in light vertical and horizontal VVOR gains were normal. In the nonparetic eye, all gains were normal. Reduced VOR gains in the direction of paretic muscles and also in the direction of their antagonists, together with normal gains in the nonparetic eye, indicate a selective adjustment to the antagonists of paretic muscles. Increase of VVOR gains to normal in the paretic eye, when used for fixation, without conjugate increase in gains in the occluded nonparetic eye, provides further evidence of selective adaptation for the paretic eye. Motions of the eyes after nerve palsies indicate monocular VOR adaptation in three dimensions.

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.

Effect of posterior tenectomy of the superior oblique on objective and subjective torsion in cases of superior oblique overaction

PURPOSE

To evaluate the effect of posterior tenectomy of the superior oblique on the correction of A-pattern, superior oblique overaction and the changes in torsion that occur in such cases.

PATIENTS AND METHODS

This prospective study included 15 consecutive cases of bilateral superior oblique overaction with an A-pattern of more than 20 PD, a difference of deviation between 25 degrees up-gaze and 35 degrees downgaze, and superior oblique overaction of 2+ to 3+ on a scale of 0 to 4+. Deviation was measured in the primary position, 25 degrees upgaze, and 35 degrees downgaze using the prism bar cover test, and torsion was measured using a synoptophore, the double Maddox rod test, and fundus photographs. Measurements were obtained preoperatively and postoperatively at 1 week, 1 month, and 3 months. All case-patients underwent a standard temporal route posterior tenectomy of the superior oblique by a single surgeon.

RESULTS

Mean age was 11.2 +/- 4.2 years with 14 cases of A-pattern exotropia. Mean superior oblique overaction was 2.60 +/- 0.50 in the right eye and 2.26 +/- 0.45 in the left eye, which decreased postoperatively to 2.20 +/- 0.56 and 1.80 +/- 0.41, respectively. The index of surgical effect was 0.84 in the right eye and 0.79 in the left eye. Postoperatively, mean correction of the A-pattern was 17.53 +/- 5.82 PD (index of surgical effect, 0.7). Subjective measurement of torsion was more consistent with the synoptophore compared with the double Maddox rod test. Objective measurement of torsion (fundus photography) was higher compared with subjective measurement. Postoperatively, there was insignificant change in the amount of torsion in upgaze and primary position.

CONCLUSION

Posterior tenectomy of the superior oblique results in significant and controlled weakening of the superior oblique and collapse of the A-pattern with a clinically insignificant change in the amount of torsion.

Idiopathic hypertrophic cranial pachymeningitis masquerading as Tolosa-Hunt syndrome

Idiopathic hypertrophic cranial pachymeningitis is a rare condition. A case of idiopathic hypertrophic cranial pachymeningitis presenting as Tolosa-Hunt syndrome is being reported. The importance of neuroimaging in patients with suspected Tolosa-Hunt syndrome is discussed. Tolosa-Hunt syndrome might represent a focal manifestation of Idiopathic hypertrophic cranial pachymeningitis. Future studies are necessary to further clarify the relationship between these two conditions.

[Head-tilt test in unilateral and symmetric bilateral acquired trochlear nerve palsy]

BACKGROUND

The head-tilt phenomenon (difference between the vertical deviations with an ipsilateral and contralateral head-tilt by 45 deg. each) occurring in patients with a superior oblique palsy has traditionally been explained by the lacking contraction of the superior oblique muscle within the synkinetic movement of ocular counterrolling. However, using a computer model, Robinson showed that the superior oblique palsy itself causes only a relatively small head-tilt phenomenon. Adaptive mechanisms amplifying the otolith reflex were suggested to explain the increase of the head-tilt phenomenon in the course of time. In order to reduce the abnormal head posture required for binocular vision, the otolith reflex would be amplified, accepting the greater vertical deviation when the head is tilted to the paretic side .

QUESTION

If the head-tilt phenomenon were solely caused by the lacking contraction of the superior oblique muscle, it should be greater in bilateral than in unilateral superior oblique palsies. If an adaptive mechanism were acting to reduce the abnormal head posture, the head-tilt phenomenon should not be greater, and could even be smaller in bilateral than in unilateral superior oblique palsy, because in bilateral (symmetric) trochlear nerve palsies the vertical deviation at straight gaze is already small or absent without adaptation.

PATIENTS AND METHODS

We have carried out a retrospective comparison of 10 patients with bilateral symmetric superior oblique palsies and 10 patients with unilateral superior oblique palsy. In all cases, the palsy was acquired and had been present for at least 1 year.

RESULTS

The patients with bilateral superior oblique palsy had a head-tilt phenomenon ranging from 0 to 7 degrees (median, 2 deg.). The patients with unilateral superior oblique palsy had a head-tilt phenomenon between 2 and 13 degrees (median, 8 deg.). The difference was significant (p = 0.0117).

CONCLUSIONS

The head-tilt phenomenon is smaller in long-standing bilateral symmetric superior oblique palsies than in long-standing unilateral superior oblique palsy. This finding supports the hypothesis that in unilateral superior oblique palsy, an adaptive mechanism augments the head-tilt phenomenon by an amplification of the otolith reflex. However, we presume that the amplification of the otolith reflex is only a side effect of the adaptive change of the vertical fusional vergence tonus and thus the price of the improved vertical fusion, rather than a compensatory mechanism.

Anterior transposition of inferior oblique muscle for treatment of unilateral superior oblique muscle palsy with inferior oblique muscle overaction

Although many weakening procedures for the inferior oblique muscle have been advocated, there is some controversy as to the most beneficial procedure for weakening overacting inferior oblique muscles. This study was undertaken to determine if unilateral anterior transposition of the inferior oblique muscle alone could be a safe and effective procedure for treating unilateral superior oblique palsy from the perspective of hypertropia, inferior oblique overaction, and abnormal head posture. The records of 33 patients, who underwent anterior transposition of the inferior oblique muscle for unilateral superior oblique palsy at our institution between Jan 1995 and Dec 2002, were retrospectively reviewed. The average preoperative inferior oblique overaction was 2.3 +/- 0.64, and the hypertropia in the primary position was 12.3 +/- 7.69 prism diopter (PD). Twenty-six patients showed head tilt to the opposite direction preoperatively. After the anterior transposition of the inferior oblique, inferior oblique overaction was diminished in 32 patients (97%). Twenty-six out of 33 patients (79%) had no hypertropia in the primary position at last postoperative assessment. Of the 26 patients with head tilt before surgery, 21 patients (81%) achieved full correction after surgery. Satisfactory results were obtained in most of the patients in our study with the exception of three patients who required additional surgery. No patient demonstrated postoperative hypotropia in the primary position. None of the patients noticed elevation deficiency or lower lid elevation. The anterior transposition of the inferior oblique was found to be safe and effective for treating superior oblique palsy with secondary overaction of the inferior oblique muscle.

Ocular Rotation Axes during Dynamic Bielschowsky Head-Tilt Testing in Unilateral Trochlear Nerve Palsy

PURPOSE

To explain the positive Bielschowsky head-tilt (BHT) sign in unilateral trochlear nerve palsy (uTNP) by the kinematics of three-dimensional eye rotations.

METHODS

Twelve patients with uTNP monocularly fixed on targets on a Hess screen were oscillated (+/- 35 degrees, 0.3 Hz) about the roll axis on a motorized turntable (dynamic BHT). Three-dimensional eye movements were recorded with dual search coils. Normal data were collected from 11 healthy subjects.

RESULTS

The rotation axis of the viewing paretic or unaffected eye was nearly parallel to the line of sight. The rotation axis of the covered fellow eye, however, was tilted inward relative to the other axis. This convergence of axes increased with gaze toward the unaffected side. Over entire cycles of head roll, the rotation axis of either eye remained relatively stable in both the viewing and covered conditions.

CONCLUSIONS

In patients with uTNP, circular gaze trajectories of the covered paretic or unaffected eye during dynamic BHT are a direct consequence of the nasal deviation of the rotation axis from the line of sight. This, in turn, is a geometrical result of decreased force by the superior oblique muscle (SO) of the covered paretic eye or, according to Hering's law, increased force parallel to the paretic SO in the covered unaffected eye. The horizontal incomitance of rotation axes along horizontal eye positions can be explained by the same mechanism.