Ocular myasthenia gravis: a review and practical guide for clinicians.

Myasthenia gravis is a rare autoimmune disease characterised by autoantibodies preventing normal function of acetylcholine receptors at the post-synaptic membrane of the neuromuscular junction. This causes weakness of skeletal muscles that can be variable and fatigable, and often manifests as ptosis and/or diplopia, with 60% of patients demonstrating ocular features at onset, and thus may present initially to eye care practitioners. Approximately 15% of patients have ocular myasthenia gravis, where symptoms remain restricted to this distribution. The majority of patients have blocking antibodies against the acetylcholine receptor, but antibodies directed against other related targets account for a smaller proportion and are associated with specific phenotypes. Associations with both thymoma and with other autoimmune phenomena (particularly thyroid disease) can occur. Clinical examination can identify characteristic findings including fatigable ptosis and Cogan's lid twitch sign. Investigations to confirm the diagnosis include simple office-based procedures such as the ice test, and testing for serum autoantibodies, as well as electrophysiological testing such as repetitive nerve stimulation and single-fibre electromyography. The management of ocular myasthenia gravis is discussed, including non-pharmacological options, pyridostigmine, corticosteroids, other immunosuppressive agents, and thymectomy. The goals of management are to alleviate symptoms, and where possible prevent chronic disability or progression to generalised myasthenia gravis.

Rapid confrontation screening for peripheral visual field defects and extinction.

Screening for unsuspected visual field defects should form a part of all routine eye examinations. Here, we review a procedure for finger-counting confrontation screening that tests the periphery of all visual field quadrants of each eye, yet requires a total of only four responses from the patient. In addition, the test simultaneously screens for the extinction phenomenon that can accompany unilateral brain damage. Due to its efficiency, we recommend that this procedure form the standard way that screening finger-counting confrontation be performed, with abnormal findings prompting a more detailed assessment of visual fields and further neurological examination as necessary. Our paper is not intended to suggest that finger-counting confrontation is superior to other forms of visual field screening and indeed the literature suggests its sensitivity is limited.

Spontaneous intracranial hypotension presenting as a reversible dorsal midbrain syndrome.

A 47-year-old woman with postural headache, episodic stupor, and vertical gaze palsy had brain imaging findings consistent with spontaneous intracranial hypotension (SIH), including severe descent of the mesodiencephalic structures and diffuse pachymeningeal enhancement. The source of the cerebrospinal fluid leakage was a ruptured dorsal perineural cyst. Clinical symptoms improved after a targeted epidural blood patch was performed. Dorsal midbrain syndrome has not been reported previously as a manifestation of SIH. Perhaps distortion of structures in this brain region can occur in SIH as it does in obstructive hydrocephalus.

Chiari 1 malformation presenting as strabismus.

INTRODUCTION: Strabismus has been previously reported as a rare presenting feature of the Type 1 Chiari malformation. CASE REPORTS: We report a case series of twelve patients with Chiari 1 malformations with either strabismus or diplopia as part of their initial presentation. Ten patients had diplopia at the time of presentation, while 2 young children (ages 2 and 6) presented with esotropia without complaints of diplopia. Of the 10 patients with diplopia, 7 were constantly or frequently tropic while 3 had symptomatic phorias. One or more unusual features of the strabismus led to further investigations and the diagnosis of Chiari in these patients. The most common oculomotor disturbance was a comitant esotropia. Most patients were managed with prism glasses. One patient had strabismus surgery as primary treatment with early orthotropia. Three patients underwent neurosurgical decompression, with minimal improvement of their strabismus; one of these underwent subsequent successful strabismus surgery. CONCLUSIONS: Chiari 1 malformation may present with strabismus or diplopia as the major finding. Associated neurological features may be nonspecific (e.g., headache), subtle (e.g., gaze-evoked nystagmus), or delayed. Although neurosurgery may be required in some cases, primary strabismus management (surgical or prismatic correction) can be successful, particularly when strabismus is the lone (or sole specific) finding.