Vertical 'half-and-half' syndrome with ipsilateral pseudo-abducens palsy due to rostral midbrain lacunar infarction.

Vertical 'half-and-half' syndrome, characterized by contralateral upward and ipsilateral downward gaze palsy, is a rare variant of vertical eye movement disturbance. Similarly, pseudo-abducens palsy, manifesting as abductive palsy despite no lesion to the pons, constitutes another rare type of eye movement disturbance. Both conditions have been associated with lesions in the thalamo-mesencephalic junction. We present a rare case report detailing a patient exhibiting vertical 'half-and-half' syndrome with ipsilateral pseudo-abducens palsy following a left lacunar infarction of the thalamo-mesencephalic junction. Additionally, we discuss the potential underlying mechanisms contributing to this rare combination of eye movement disorders.

The diagnostic value of the ocular tilt reaction plus head tilt subjective visual vertical (±45°) in patients with acute central vascular vertigo.

Objectives: To investigate the localization diagnostic value of the ocular tilt reaction (OTR) plus head tilt subjective visual vertical (SVV) in patients with acute central vascular vertigo (ACVV). Methods: We enrolled 40 patients with acute infarction, 20 with unilateral brainstem infarction (BI) and 20 with unilateral cerebellar infarction (CI). We also included 20 patients with unilateral peripheral vestibular disorders (UPVD) as the control group. The participants completed the OTR and SVV during head tilt (±45°) within 1 week of symptom onset. Results: In patients with ACVV, including that caused by lateral medullary infarction (100%, 2/2), partial pontine infarction (21%, 3/14), and cerebellum infarction (35%, 7/20), we observed ipsiversive OTR, similar to that seen in UPVD patients (80.0%, 16/20). Some of the patients with medial medullary infarction (50%, 1/2), partial pons infarction (42%, 6/14), midbrain infarction (100%, 2/2), and partial cerebellum infarction (30.0%, 6/20) showed contraversive OTR. The skew deviation (SD) of the BI group with ACVV was significantly greater than that of the UPVD group (6.60 ± 2.70° vs. 1.80 ± 1.30°, Z = -2.50, P = 0.012), such that the mean SD of the patients with a pons infarction was 9.50° and that of patients with medulla infarction was 5.00°. In ACVV patients with no cerebellar damage, the area under the curve of the receiver operating characteristic curve corresponding to the use of SD to predict brainstem damage was 0.92 (95%CI: 0.73-1.00), with a sensitivity of 100% and a specificity of 80% when SD ≥ 3°. We found no statistical difference in SD between the UPVD and CI groups (1.33 ± 0.58° vs. 1.80 ± 1.30°, Z = -0.344, P = 0.73). Compared with the UPVD patients, the ACVV patients with a partial pons infarction (43%, 6/14, χ2 = 13.68, P = 0.002) or medulla infarction (25%, 1/4, χ2 = 4.94, P = 0.103) exhibited signs of the ipsiversive E-effect with the contraversive A-effect, while those with a partial medulla infarction (50%, 2/4), pons infarction (43%, 6/14), or cerebellar infarction (60%, 12/20) exhibited a pathological symmetrical increase in the E-effect. Conclusions: The evaluation of OTR plus head tilt SVV (±45°) in vertigo patients is helpful for identifying and diagnosing ACVV, especially when SD is ≥ 3° or the E-effect is symmetrically increased.

Evaluation and Management of Symptomatic Vertical Strabismus and Diplopia.

The evaluation and management of vertical strabismus is more challenging and nuanced than that of horizontal strabismus. Vertical strabismus often results from a variety of restrictive or paretic causes, which can be further characterized as either acquired or congenital. In some cases, identifying the correct etiology of the strabismus can mean uncovering a potentially life-threatening condition, such as a brain tumor or stroke. The keys to identifying the correct diagnosis are, first and foremost, a careful history, and secondly, a detailed examination. The characteristics, etiologies, and evaluation of vertical strabismus will be reviewed here.

Parks 3-step test.

Background: The Parks 3-step test is an important test in the diagnosis of a single cyclovertical muscle palsy. Purpose: This video is presented to provide a simplified and easy understanding of the Parks 3-step test for post-graduate residents. Synopsis: The video contains a description of the steps to perform a 3-step test, the results of the test in a case of superior oblique palsy, the conditions that mimic a positive 3-step test, and how to identify these mimicking conditions. Highlights: This is a simple demonstration of a classic clinical diagnostic procedure. Online Video Link: https://youtu.be/1wpjwe19c0E.

Objective measurement of HINTS (Head Impulse, Nystagmus, Test of Skew) in peripheral vestibulopathy.

OBJECTIVE: To evaluate how often the positive sign of HINTS (Head-Impulse, Gaze Evoked Nystagmus, Test of Skew) appears in patients with acute peripheral vestibular lesion, HINTS findings were quantitatively measured and analyzed in patients with peripheral vestibulopathy accompanying spontaneous nystagmus. METHODS: HINTS was evaluated in 14 vertigo patients with spontaneous nystagmus. Horizontal vestibulo-ocular reflex (VOR) gain was measured using the video head impulse test (vHIT). To evaluate gaze-evoked nystagmus (GEN), slow-phase velocities at different points of lateral gaze were measured and plotted, then the slope and its inverse value, the neural integrator time constant, were calculated. Skew deviation was tested using anaglyph filters to simulate the alternate cover test, and the degree and latency of vertical eyeball deviation were measured. The ABCD2 score was calculated to evaluate the risk of stroke. RESULTS: Among 13 patients of peripheral vestibulopathy, 7 showed positive signs in HINTS (normal vHIT: 5, direction-changing GEN: 0, skew deviation: 3). One patient with a cerebellopontine angle tumor presented with both a peripheral and central pattern and showed positive HINTS findings (presence of direction-changing GEN). The mean VOR gain of patients with abnormal vHIT was 0.58±0.29 and 1.10±0.11 in the affected and contralateral side, respectively, while those in patients with normal vHIT were 1.04±0.21 and 1.13±0.12, respectively. The neural integrator time constant calculated from the mean slope of horizontal slow-phase velocity according to horizontal eye position was 42.9 s. The mean vertical eyeball deviation of patients with positive skew was 2.14±1.18° while uncovering the eye on the affected side, and -1.97±1.59° while uncovering the eye on the unaffected side. The median ABCD2 score of 14 patients was 2 (range, 1-3). CONCLUSIONS: HINTS findings were objectively measured in vertigo patients with spontaneous nystagmus. Although positive findings of HINTS have been recognized as a central sign, 54% (7/13) of cases with peripheral vestibulopathy showed positive HINTS signs. HINTS results should be interpreted carefully considering that a substantial proportion of peripheral vestibulopathy shows a positive HINTS sign.

Automated alternate cover test for 'HINTS' assessment: a validation study.

OBJECTIVE: The alternate cover test (ACT) in patients with acute vestibular syndrome is part of the 'HINTS' battery test. Although quantitative, the ACT is highly dependent on the examiner's experience and could theoretically vary greatly between examiners. In this study, we sought to validate an automated video-oculography (VOG) system based on eye tracking and dedicated glasses. METHODS: We artificially induced a vertical strabismus to simulate a skew deviation on ten healthy subjects, aged from 26 to 66, using different press-on Fresnel prisms on one eye while recording eye position with VOG of the contralateral eye. We then compared the system's performance to that of a blinded trained orthoptist using conventional, semi-quantitative method of skew measurement known as the alternate prism cover test (APCT) as a gold standard. RESULTS: We found a significant correlation between the reference APCT and the Skew VOG (Pearson's R2 = 0.606, p < 0.05). There was a good agreement between the two tests (intraclass correlation coefficient 0.852, 95 CI 0.728-0.917, p < 0.001). The overall accuracy of the VOG was estimated at 80.53% with an error rate of 19.46%. There was no significant difference in VOG skew estimations compared with the gold standard except for very small skews. CONCLUSIONS: VOG offers an objective and quantitative skew measurement and proved to be accurate in measuring vertical eye misalignment compared to the ACT with prisms. Precision was moderate, which mandates a sufficient number of tests per subject.

Reliability of two dissociating tests of phoria in artificially created phoria in normal adults.

BACKGROUND: The ability of physical therapists (PTs) to accurately identify and reliably measure phoria/tropia is critical in the differential diagnosis of individuals with acute vestibular syndrome and concussion/mild traumatic brain injury. OBJECTIVES: To determine if PTs may reliably measure phoria and to determine the reliability of two dissociating tests of phoria, the prism neutralized Maddox rod test and modified Thorington method, in normal adults with artificially created phoria. METHODS: Thirty adults (mean age 24.87 ± 4.74 years) were randomly assigned to wear trial lenses (1, 2, 4, or 6 pd prism left, plain glass right) to create phoria. In sitting and supine, phoria was measured using prism neutralized Maddox rod test and modified Thorington method. Mean, SD, and range of first neutral endpoint were calculated for each examiner. Percentage of trials in agreement (≤ 2 and 4 pd); comparisons within the linear mixed effects regression model; and inter-rater reliability between examiners was calculated with the intra-class correlation coefficient (ICC). RESULTS: Participants underwent 20 measurements by each examiner. Trial agreement between examiners was 74% (range 13%-100%) in horizontal and 91% (range 63%-100%) in vertical plane. Maddox rod test had significantly different means between two examiners (P < .05). Modified Thorington test had no significant difference. The Maddox rod test had a significant examiner main effect, examiner 2 always scored lower. Inter-rater correlation coefficient for each test was significant at level of P < .01 (ICC ≥ 0.67 ≤ 0.94) except for modified Thorington test in supine, horizontal plane with P < .05 (ICC ≥ 0.38). CONCLUSION: PTs may reliably measure artificially created phorias using prism neutralized Maddox rod test and modified Thorington method.

Congenital ocular counter-roll: a review of cases treated exclusively by ophthalmologists.

AIM: To review the demographics, clinical manifestations, and surgical experiences of patients with congenital ocular counter-roll, whose treatments were performed exclusively by ophthalmologists. METHODS: A retrospective review was conducted consisting of patients who received strabismus surgery between 2017 to 2019. Patients with obvious ocular counter-roll were included. RESULTS: A total of 7008 patients who received strabismus surgery, 28 (12 males, 16 females) were diagnosed as congenital ocular counter-roll, accounting for 0.40%. All patients were initially misdiagnosed: 21 patients were misdiagnosed as superior oblique palsy (SOP), 3 as inferior oblique overaction, 2 as dissociated vertical deviation (DVD), 1 as superior oblique overaction with A-pattern exotropia, and 1 as medial rectus palsy. The mean±SD age was 12.4±9.4y (range 2.5-36y). The most common clinical findings included ocular counter-roll, vertical deviation or vertical deviation combined with outward deviation and head tilt. At follow-up, an excellent surgical result was achieved in 20 patients. Preoperative horizontal deviation of 26±24 prism diopter (PD) and vertical deviation of 18±12 PD were reduced to 0±12 PD (P=0.0001) and 3±4 PD (P=0.001), respectively. CONCLUSION: Congenital ocular counter-roll is a rare supranuclear vertical strabismus caused by congenital abnormalities involving vestibule-ocular reflex pathways. In addition to ocular counter-roll, the most salient clinical features included, but are not limited to, hyperdeviation, outward deviation, overelevation in adduction and head tilt.

Analysis of the Skew Deviation to Evaluate the Period of Onset of a Canalolithiasis After Macular Damage.

Benign paroxysmal positional vertigo (BPPV) is the most common peripheral vestibular end-organ disease, and it is one of the first causes of access to the emergency room. The moment of migration of the otoconial debris in a semicircular canal does not necessarily coincide with the moment of detachment of the debris themselves. Consequently, the paroxysmal positional vertigo could arise with a variable delay with respect to the mechanical damage suffered by the macula. The aim of this work is to try to identify objective criteria to establish whether a canalolithiasis is synchronous or diachronic to the damage. The analysis of skew deviation in the context of ocular tilt reaction in patients with canalolithiasis could provide useful information to understand if macular damage occurred at the origin of the disease and when the damage may have occurred. In this study, 38 patients with BPPV were analyzed based on the type of skew deviation that was presented. We found that if the eye on the side of the canalolithiasis is hypotropic the damage of the utriculus is likely recent (last 10 days), if it is hypertropic the damage is not recent (20 days before) and finally if the eyes are at the same height it could be an utricular damage in compensation (occurring the last 10-20 days) or a secondary labyrinth canalolithiasis, without associated utricular damage. Our results show that the evaluation of skew deviation in patients suffering from BPPV could be useful to evaluate: (a) if a positional paroxysmal nystagmus can be related to an previous relevant injury event (for example a head injury that occurred days before the crisis); (b) if it is a BPPV of recent onset or a re-entry of the debris into the canal.

A case of skew deviation and downbeat Nystagmus induced by Lithium.

BACKGROUND: Lithium salts have been commonly used for prophylaxis and treatment of bipolar disorder and have numerous side effects. However, there has been no report of skew deviation and downbeat nystagmus associated with lithium. Herein, we report the first case of lithium-induced skew deviation and downbeat nystagmus. CASE PRESENTATION: A 39 years-old woman presented with intermittent vertical diplopia and dizziness within 1-2 months. Ophthalmologic examination revealed downbeat nystagmus and 6 prism diopters of right hypertropia. Funduscopic examination showed mild incyclotorsion on right eye. However, ductions and versions were within normal range. Other neurological examinations were also normal. She had a history of bipolar disorder treated with daily 600-900 mg of lithium for past 6 years, and 2 months before the first visit, daily dose of lithium was increased to 1200 mg. We referred the patients to psychiatrist. Although the serum level of lithium was within the normal therapeutic range, her daily dose of lithium was reduced to 600 mg and then stopped. 6 days after cessation of lithium, down beat nystagmus and right hypertropia were completely resolved and symptoms did not recur over a year. CONCLUSION: Even within a normal therapeutic range, downbeat nystagmus and skew deviation can occur as side effect of lithium. Dehydration may contribute to the neurotoxicity of lithium.

Stiff-Person Syndrome: A Case Report and Review of the Literature.

AIM: To report a case of sudden onset vertical diplopia, blurred vision, and muscle spasms. METHODS: This is a case report of a 57-year-old female who presented to the accident and emergency department with a one day history of vertical diplopia and a two week history of lower limb spasticity secondary to muscle spasms. RESULTS: The patient had no significant medical or ocular history. Orthoptic investigation initially revealed a left inferior rectus (IR) underaction. Possible diagnoses at this point were thought to be isolated IR weakness, myasthenia gravis or skew deviation. An urgent MRI scan was arranged and blood tests were taken. MRI showed no abnormalities. Blood tests were normal, however, the acetylcholine receptor antibody serum test (ACH-R) was 0.43 nmol/L, which is at the high end of normal. At the follow-up visit, the IR weakness had deteriorated and the patient had also developed gaze-evoked nystagmus. An appointment with the neurologist and neuro-ophthalmologist was expedited. When the patient returned, she reported that her neurologist had diagnosed her with stiff-person syndrome (SPS). The patient had also developed a laterally alternating skew deviation and reported that she had undergone a course of intravenous immunoglobulin (IVIG). The patient was prescribed diazepam and gabapentin. Due to the lack of recovery, persistent diplopia and oscillopsia, monthly IVIG have been prescribed. CONCLUSION: There is currently a paucity of literature relating to ophthalmic problems with SPS and how they are best treated. Previous reports have established that there is a link with myasthenia gravis, with many patients going on to develop myasthenia. Treatment of SPS is lacking large evidence-based studies. However, treatment with muscle relaxants and anticonvulsants has provided a good outcome for some. Further research is required to develop an evidence-based approach to treating the ophthalmological problems patients with SPS experience. This case report highlights the importance and value of orthoptists in investigating and monitoring patients with stiff-person syndrome.

Ipsiversive Ocular Torsion, Skew Deviation, and Hearing Loss as Initial Signs of Anterior Inferior Cerebellar Artery Infarction.

A 67-year-old man with hypertension and type 2 diabetes mellitus was admitted to our hospital because of left hearing loss and vertical diplopia. A neurological examination showed ocular torsion, skew deviation, and sensorineural hearing loss in the left ear. Brainstem and cerebellar neurological signs were not observed. Left middle cerebellar peduncle infarction was evident on magnetic resonance imaging. He was treated with antiplatelet, however, the infarct progressed after this administration. Ocular tilt reaction (OTR) involves the triad of ocular torsion, skew deviation, and head tilt. Ipsiversive OTR components associated with hearing loss can be early diagnostic signs of anterior inferior cerebellar artery infarction.

Misleading signs in acute vertigo.

The acute vestibular syndrome is common and usually has a benign cause. Sometimes, however, even experienced neurologists can find it difficult to determine the cause clinically. Furthermore, neuroimaging is known to be insensitive.We describe two cases of acute vestibular syndrome where conflicting clinical findings contributed to a delay in making the correct diagnosis. The first patient with symptomatic vertigo had signs consistent with horizontal benign paroxysmal positional vertigo but also had an abnormal horizontal head impulse test, superficially suggesting acute vestibular neuritis but later accounted for by the finding of a vestibular schwannoma (acoustic neuroma). The second patient also had an abnormal horizontal head impulse test, with skew deviation suggesting stroke as the cause. However, later assessment identified that a long-standing fourth nerve palsy was the true cause for her apparent skew. We discuss potential errors that can arise when assessing such patients and highlight ways to avoid them.

Skew Deviation and Partial Ocular Tilt Reaction Due to Intratympanic Gentamicin Injection, with Review of the Literature.

Skew deviation is a rare side effect of intratympanic gentamicin injection for intractable Meniere's disease. When the skew deviation is accompanied by pathologic head tilt and ocular torsion, the result is an ocular tilt reaction (OTR). The authors report the case of a 56-year-old man with refractory Meniere's disease who developed binocular vertical diplopia following intratympanic gentamicin injection and was found to have skew deviation and a partial ocular tilt reaction. The authors also review the reported cases of skew deviation following intratympanic gentamicin and confirm this phenomenon, which has only rarely been reported in the literature.

Skew Deviation: Case Report and Review of the Literature.

OBJECTIVE: To present a patient with a sudden onset ocular tilt reaction (OTR) and review recent knowledge and evolving insights of the underlying pathophysiological mechanisms of skew deviation and OTR. METHODS: A middle-aged hypertensive man who had previously suffered stroke with good recovery presented with sudden-onset double vision, slurred speech, ataxia, and a head tilt. Romberg test was positive. The patient denied having disturbances of visual acuity, eye pain, or recent trauma. The right eyeball was pushed upward. The patient complained of double vision in any gaze direction. Movements of the extraocular muscles (EOMs) in the horizontal plane were normal, whereas vertical version and convergence were not possible. We administered a Hess-Lancaster test, cover test, fundoscopic examination, Parks-Bielschowsky three-step test, upright-supine test, brain magnetic resonance imaging (MRI), transcranial doppler (TCD) ultrasonography, electrocardiogram (ECG), Holter monitor (24 h), and echocardiography. RESULTS: The Hess-Lancaster test showed superior rectus muscle and inferior obliquus muscle palsy to the left and rectus inferior muscle and superior obliquus muscle palsy to the right. The right eyeball fell behind when looking downward and the left eyeball when looking upward. Cover alternating test was positive from vertical, R/L. Examination of the ocular fundus showed incyclotorsion of elevated right eye and excyclotorsion of depressed eye. The Parks-Bielschowsky three-step test was negative. A brain MRI with gadolinium revealed a small zone of diffusion restriction in the medial portion of the right cerebral peduncle and right thalamus. There was a gradual improvement in the patient's neurological status following treatment. CONCLUSION: Skew deviation, a not uncommon clinical condition, should be promptly recognized when binocular vertical diplopia cannot be interpreted by trochlearis and oculomotor nerve lesion, myasthenia gravis, or orbital pathology. Maddox rod, cover test, Parks-Bielschowsky three-step, and other tests should help to establish the diagnosis. The prognosis depends on etiology, but it is commonly favorable; the majority of patients recover spontaneously after less than a year. More invasive management options should be discussed thereafter.

Bedside examination.

In most dizzy patients a limited selection of bedside tests, together with the history, is adequate to establish a differential diagnosis and select the next diagnostic and therapeutic procedures. A set of basic bedside tests that should be applied in every patient with vertigo or imbalance allows identifying: (1) patients who need immediate referral for further assessment and treatment; (2) patients with nonthreatening disorders for which treatment can be started without more detailed testing; (3) patients with benign paroxysmal vertigo, in whom a detailed work-up is not required and who can immediately be treated with an appropriate particle-repositioning maneuver; and (4) patients who need a comprehensive neuro-otologic and neurologic work-up. Additional neuro-otologic bedside tests help to further refine the differential diagnosis.