Progressive cerebellar tonsillar herniation with recurrent divergence insufficiency esotropia

Divergence insufficiency alleviated by posterior fossa decompression with duraplasty in a patient with Chiari type 1.5 malformation

The authors present a case of Chiari type 1.5 malformation with the uncommon presenting symptoms of esotropia and diplopia due to divergence insufficiency in a 12-year-old girl. Imaging at initial diagnosis revealed cerebellar herniation with extension of the tonsils to the C2 vertebral body, a retroflexed odontoid, and a small cervical syrinx. The patient was initially treated with an uncomplicated Chiari malformation decompression without dural opening. Repeat imaging revealed an adequate decompression. Three months postoperatively the patient's diplopia recurred and she underwent repeat posterior fossa decompression with dural opening and duraplasty. Following repeat decompression with dural opening and duraplasty, the patient's diplopia had not recurred by the 2-year follow-up.https://thejns.org/doi/abs/10.3171/2018.5.PEDS1886.

Neuro-ophthalmology of type 1 Chiari malformation

Chiari malformation is a congenital deformity leading to herniation of cerebellar tonsils. Headache is a typical symptom of this condition, but patients with Chiari malformation often present with double vision and vertigo. Examination of eye movements in such patients often reveals nystagmus and strabismus. Eye movement deficits in the context of typical symptomatic presentation are critical clinical markers for the diagnosis of Chiari malformation. We will review eye movement deficits that seen in patients with type 1 Chiari malformation. We will then discuss the underlying pathophysiology and therapeutic options for such deficits.

Esophoria or esotropia in adulthood: a sign of cerebellar dysfunction?

Convergent strabismus is a common diagnosis in early childhood, when it is mostly considered benign. If it develops later in life, strabismus can, however, be a sign of neurological disease. In these cases the underlying pathophysiological mechanisms are largely unknown. In this retrospective case-control study we analyzed the neuro-ophthalmological examination reports of 400 adult patients who presented at the German Center for Vertigo and Balance Disorders to determine an association between ocular misalignment and cerebellar dysfunction. Patients with cerebellar signs (i.e., cerebellar ataxia and/or cerebellar ocular motor signs) had a 4.49 (95 % CI [1.60; 13.78]) times higher frequency of ocular misalignment and specifically a 13.3 (95 % CI [3.80; 55.73]) times increased frequency of esophoria/esotropia (ESO) during distant gaze than patients without cerebellar dysfunction. ESO when looking into the distance was associated with saccadic smooth pursuit, dysmetria of saccades, and downbeat nystagmus (DBN) (χ (2) test, p < 0.0001 for all associations). Patients with cerebellar dysfunction also showed mildly impaired eye abduction (χ (2) test, left eye and right eye: p < 0.0001), associated with horizontal gaze-evoked nystagmus (χ (2) test, p < 0.0001). The association of ESO and DBN implicates a pathophysiological involvement of the cerebellar flocculus, while the association with dysmetric saccades suggests involvement of the oculomotor vermis. This is compatible with animal studies showing that the pathways of the flocculus/posterior interposed nucleus and vermis/nucleus fastigii are both involved in vergence movements and static binocular alignment. From a clinical point of view, a newly diagnosed esophoria/esotropia only during distant gaze may be a sign of a cerebellar disease.

Impaired body balance control in adults with strabismus

Previous studies revealed that people with binocular vision disorders have poor postural stability. However, most of the research was performed only on children and under binocular viewing condition, that could negatively affect the results. The aim of the current study was to investigate the influence of extra-ocular proprioceptive signals on postural stability in young adults with binocular vision disorders. Moreover, additional mental task was introduced to detect any postural compensation which could possibly hide the real influence of afferent extra-ocular signals. 21 Subjects, aged 18-45 yrs, with horizontal strabismus, were qualified to binocular vision disorders (BVD) group. 41 subjects, aged 19-45 yrs, with no strabismus formed the normal binocular vision (NBV) group. Posturography data were collected in 2 separate parts: (1) quiet standing (Single-Task), and (2) performance of a mental task while standing (Dual-Task). Each part consisted of three 60-s viewing conditions, with: (1) dominant/fellow eye (DE), (2) non-dominant/strabismic eye (NDE), and with (3) both eyes closed (EC). Subjects were looking at X located at the distance of 150 cm. Generally, BVD group showed elevated body balance during quiet stance compared to NBV group. Interestingly, better stabilization in BVD group occurred under NDE viewing. Surprisingly, additional mental task improved the postural stability in BVD group almost to the level of NBV group. These findings emphasize the role of the eye-muscle signals in postural control and suggest that suitable vision therapy can be the appropriate way to improve body balance/motor functions in people with binocular vision disorders.

Divergence insufficiency

INTRODUCTION AND PURPOSE

To compare the clinical characteristics of a population of patients with divergence insufficiency in the absence of associated neurologic disease to those patients with divergence insufficiency and an associated neurologic disorder.

PATIENTS AND METHOD

A retrospective review of 251 patients diagnosed with divergence insufficiency and/or divergence paralysis. Clinical features include the age at onset, fusional divergence amplitudes, the size of the esodeviation, treatment offered, and the presence or absence of associated neurologic conditions. Classification into primary and secondary divergence insufficiency solely depended on the absence or presence of neurologic disorders, respectively.

RESULTS

The incidence of neurologic disease associated with divergence insufficiency was 17%. The average age at onset was 62 years for primary and 51 years for secondary divergence insufficiency. Nystagmus was noted in 43% of secondary divergence insufficiency patients and 0.01% of primary divergence insufficiency patients. Both groups exhibited decreased fusional divergence at distance fixation while retaining normal fusional divergence at near.

CONCLUSIONS

The majority of patients were classified as primary divergence insufficiency. Though this form of divergence insufficiency is neurologically benign, it may easily mask a more severe neurologic condition for which the presenting symptom is also diplopia for distance viewing only. These results show the importance of obtaining a detailed history regarding the symptoms, as well as documenting neurologic signs, particularly nystagmus, when investigating divergence insufficiency.