Brown syndrome: a literature review

The current data on various aspects of Brown syndrome are limited and sporadic. This review provides a coherent and comprehensive review of basic features, etiology, classification, differential diagnosis, and different management strategies of patients with Brown syndrome. In this topical review, PubMed, Scopus, and Google Scholar search engines were searched for papers, published between 1950 and January 2023 based on the keywords of this article. The related articles were collected, summarized, categorized, assessed, concluded, and presented. Brown syndrome is identified by restricted passive and active elevation of the eye in adduction. The condition is divided into congenital and acquired causes. The clinical features result from a restricted motion of the superior oblique tendon sheath through the trochlea while trying to look up in adduction. The newest explanation of the underlying pathophysiology has been explained as the presence of a fibrotic strand in the superior oblique muscle tendon with variable insertion sites which creates various elevation deficits seen in Brown syndrome. The most common clinical features include the presence of an abnormal head posture, V-pattern strabismus, and hypotropia in the primary position. Management of Brown syndrome includes watchful observation, surgical, and non-surgical procedures. Some cases might resolve spontaneously without any intervention; however, some acquired cases might require systemic and/or intra-trochlear steroid administration to treat the underlying causes. Surgical procedures such as superior oblique tenectomy and using a silicon tendon expander are indicated in the presence of hypotropia and significant abnormal head posture in the primary position.

Is a Depth Camera in Agreement with an Electromagnetic Tracking Device when Measuring Head Position?

Introduction

Clinicians typically observe and describe abnormal head postures (AHPs) and may also measure them. Depth cameras have been suggested as a reliable measurement device for measuring head position using face-tracking technology. This study compared a depth camera (Microsoft Kinect) to a gold standard electromagnetic tracking system (Polhemus device) to measure head position.

Method

Twenty healthy volunteers (mean age 21 years) had their head position simultaneously recorded using the depth camera (Kinect) and the electromagnetic tracking system (Polhemus). Participants were asked to make 30-degree head movements into chin up, chin down, head turn and head tilt positions. The head movement made and the stability of the head at each position were recorded and analysed.

Results

Compared to the electromagnetic tracking system (Polhemus), the depth camera (Kinect) always measured a smaller head movement. Measurements with the two devices were not statistically significantly different for turn right (P = 0.3955, p > 0.05), turn left (P = 0.4749, p > 0.05), tilt right (P = 0.7086, p > 0.05) and tilt left (P = 0.4091, p > 0.05) head movements. However, the smaller depth camera measurement of chin up and chin down head movements were statistically significant, chin up (P = 0.0001, p < 0.01) and chin down (P = 0.0005, p < 0.001). At each eccentric position, the depth camera (Kinect) recordings were more variable than the electromagnetic tracking system (Polhemus).

Conclusions

Compared to the electromagnetic tracking system (Polhemus), the depth camera (Kinect) was comparable for measuring head turns and tilts but was less accurate at measuring chin up and chin down head positions. Further research is needed before the depth cameras are considered for clinical recordings of head position.

Abnormal Head Posture in Unilateral Superior Oblique Palsy

Purpose: To evaluate the manifestations and severity of abnormal head posture (AHP) in unilateral congenital and acquired superior oblique palsy (SOP) patients and to assess the effect of AHP on facial appearance. Patients and methods: This case series study was performed on 60 consecutive SOP patients, which consisted of 47 patients with congenital SOP and 13 patients with the acquired source. The exact type of AHP in congenital and acquired cases was determined based on direct observation. In addition, a close-up picture from 40 cm with habitual AHP was captured from all patients. For evaluation of the severity of AHP and measurement of head tilt, these pictures were analyzed by the Corel Draw X7 software (Corel Corp, Canada). Besides, qualitative and quantitative facial asymmetry parameters were evaluated by the assessment of pictures of patients, which were taken in different gazes. Results: Five different manifestations of AHP were observed to the contralateral side of the palsy; 1 - pure head tilt, 2 - simultaneous head tilt and turn, 3 - pure head turn, 4 - head tilt and chin down, and 5 - head tilt and turn with chin down. The frequency of these five manifestations of AHP in the congenital group were 23 (48.9%), 10 (21.3%), 4 (8.5%), 5 (10.6%), and 5 (10.6%) patients, respectively (P <.001) and in acquired patients, were 1 (7.7%), 8 (61.5%), 2 (15.4%), 2 (15.4%), and 0 (0%), respectively (P =.024). In all SOP patients, the most common manifestations of AHP were pure head tilt (40%), simultaneous head tilt and turn (30%), and head tilt with chin down (11.7%), respectively. The mean degrees of head tilt in congenital and acquired patients were 15.10° ± 9.34° and 9.61° ± 5.84°, respectively (P =.022). Conclusion: The most common type of AHP in congenital SOP patients was contralateral head tilt, but in acquired cases was simultaneous head tilt and turn. The mean amount of head tilt in the acquired group was significantly higher than congenital patients; in contrast, the frequency of facial asymmetry was higher in the congenital group compared with the acquired patients.

Current and emerging treatments for albinism

Albinism is a group of rare inherited disorders arising from impairment of melanin biosynthesis. The reduction of melanin synthesis leads to hypopigmentation of the skin and eyes. A wide range of ophthalmic manifestations arise from albinism, including reduction of visual acuity, nystagmus, strabismus, iris translucency, foveal hypoplasia, fundus hypopigmentation, and abnormal decussation of retinal ganglion cell axons at the optic chiasm. Currently, albinism is incurable, and treatment aims either surgically or pharmacologically to optimize vision and protect the skin; however, novel therapies that aim to directly address the molecular errors of albinism, such as l-dihydroxyphenylalanine and nitisinone, are being developed and have entered human trials though with limited success. Experimental gene-based strategies for editing the genetic errors in albinism have also met early success in animal models. The emergence of these new therapeutic modalities represents a new era in the management of albinism. We focus on the known genetic subtypes, clinical assessment, and existing and emerging therapeutic options for the nonsyndromic forms of albinism.

Outcomes of Extraocular Muscle Surgery for Diplopia or Abnormal Head Posture After Treatment of Brain Disease

Purpose

To report the characteristics and outcomes of extraocular muscle (EOM) surgery for diplopia and abnormal head posture (AHP) after treatment of severe brain diseases such as brain tumor, severe cerebral bleeding and cerebral infarction.

Patients and Methods

Sixty-four patients (mean age 53.7 ± 16.0 years) who underwent EOM surgery to eliminate diplopia or AHP after treatment for brain disease at Hyogo College of Medicine Hospital from March 2006 through February 2018 were included. We divided the patients into two groups: a severe cerebrovascular disorder (SCVD) group and a brain tumor (BT) group. Backgrounds, surgical outcomes and satisfaction with treatment outcomes were examined retrospectively and compared between the two groups. The NEI-VFQ 25, Japanese version, was used to quantify postoperative satisfaction.

Results

There were 26 patients in the SCVD group and 38 patients in the BT group. The average age for the BT group was significantly younger than that for the SCVD group (P = 0.0236). The period from the onset of diplopia to EOM surgery was approximately 4 years for both groups. Abducens palsy was the most frequent disturbance (27% in the SCVD group and 52.6% in the BT group), and the numbers of operations were similar between the 2 groups (1.3 ± 0.7 and 1.3 ± 0.5 operations, respectively). In total, diplopia was eliminated in 82.8% of cases and AHP improved in 81.6% of cases. The BT group scored significantly higher than the SCVD group on 8 out of the 11 items on the VFQ 25.

Conclusion

EOM surgery was effective in eliminating diplopia and AHP. Therefore, we recommend that these patients visit an ophthalmologist as soon as possible and undergo EOM surgery.

Management of Duane retraction syndrome with prismatic glasses

PURPOSE

To report the results of using prismatic glasses for Duane retraction syndrome (DRS).

METHODS

Data were obtained from the records of patients who were evaluated during the year 2000 in the Strabismus Unit of the Beyoglu Eye Training and Research Hospital. The average follow-up was 12.2±17.7 months. In all cases, 2 main variables were evaluated: horizontal deviation in the primary position and face turn. Prismatic glasses were provided to patients according to the degree of shift in the primary position.

RESULTS

The mean age of patients was 11.2 years. An analysis was performed on the data collected from 12 cases; 7 patients were females (58.3%) and 5 were males (41.7%), with 11 (91.7%) cases being of type I DRS. All 12 patients had abnormal head posture (face turn) and an angle of mean deviation equaling 10 PD (prism dioptri).

CONCLUSION

Treatment was individualized on a case-by-case basis. Prismatic glasses are useful for eliminating abnormal head posture and ocular misalignment in selected cases.

Binocular vision and abnormal head posture in children when watching television

AIM

To determine the association between the binocular vision and an abnormal head posture (AHP) when watching television (TV) in children 7-14y of age.

METHODS

Fifty normal children in the normal group and 52 children with an AHP when watching TV in the AHP group were tested for spherical equivalents, far and near fusional convergence (FC) and fusional divergence (FD) amplitudes, near point of convergence, far and near heterophoria, accommodative convergence/ accommodation ratio and stereoacuity. The values of these tests were compared between the two groups. The independent t test was applied at a confidence level of 95%.

RESULTS

The far and near FC amplitudes and far FD amplitudes were lower in the AHP group (the far FC amplitudes: break point 13.6±5.4(Δ), recovery point 8.7±5.4(Δ). The near FC amplitudes: break point 14.5±7.3(Δ), recovery point 10.3±5.1(Δ). The far FD amplitudes: break point 3.9±2.7(Δ), recovery point 2.6±2.3(Δ)) compared with those in the normal group (the far FC amplitudes: break point 19.1±6.2(Δ), recovery point 12.4±4.5(Δ). The near FC amplitudes: break point 22.3±8.0(Δ), recovery point 16.1±5.7(Δ). The far FD amplitudes: break point 7.0±2.1(Δ), recovery point 4.6±1.9(Δ)). Other tests presented no statistically significant differences.

CONCLUSION

An association between the reduced FC and FD amplitudes and the AHP in children when watching TV is proposed in the study. This kind of AHP is considered to be an anomalous manifestation which appears in a part of puerile patients of fusional vergence dysfunction.

Nystagmus in childhood

Nystagmus is an involuntary rhythmic oscillation of the eyes, which leads to reduced visual acuity due to the excessive motion of images on the retina. Nystagmus can be grouped into infantile nystagmus (IN), which usually appears in the first 3-6 months of life, and acquired nystagmus (AN), which appears later. IN can be idiopathic or associated to albinism, retinal disease, low vision, or visual deprivation in early life, for example due to congenital cataracts, optic nerve hypoplasia, and retinal dystrophies, or it can be part of neurological syndromes and neurologic diseases. It is important to differentiate between infantile and acquired nystagmus. This can be achieved by considering not only the time of onset of the nystagmus, but also the waveform characteristics of the nystagmus. Neurological disease should be suspected when the nystagmus is asymmetrical or unilateral. Electrophysiology, laboratory tests, neurological, and imaging work-up may be necessary, in order to exclude any underlying ocular or systemic pathology in a child with nystagmus. Furthermore, the recent introduction of hand-held spectral domain optical coherence tomography (HH SD-OCT) provides detailed assessment of foveal structure in several pediatric eye conditions associated with nystagmus and it can been used to determine the underlying cause of infantile nystagmus. Additionally, the development of novel methods to record eye movements can help to obtain more detailed information and assist the diagnosis. Recent advances in the field of genetics have identified the FRMD7 gene as the major cause of hereditary X-linked nystagmus, which will possibly guide research towards gene therapy in the future. Treatment options for nystagmus involve pharmacological and surgical interventions. Clinically proven pharmacological treatments for nystagmus, such as gabapentin and memantine, are now beginning to emerge. In cases of obvious head posture, eye muscle surgery can be performed to shift the null zone of the nystagmus into the primary position, and also to alleviate neck problems that can arise due to an abnormal head posture.