Ocular aspects of myasthenia gravis

Enhancement of contralateral ptosis on passively holding an eyelid in mitochondrial myopathy resembling myasthenia gravis

Ptosis has long been recognized as a presenting sign of myasthenia gravis, and the appearance of ptosis or increasing ptosis with passive lid elevation of opposite eye is a useful bedside diagnostic test for this disease. We describe a patient whose ptosis worsened in either eye when the examiner passively held the opposite eyelid. She was initially thought to have myasthenia gravis, but ultimately it was discovered her ocular findings were caused by a mitochondrial myopathy.

Immunological and electrophysiological investigations of severe ptosis after bone marrow transplantation

Ocular problems are common in recipients of stem cell transplantation (SCT), but ptosis is rarely reported and investigated. Among 346 consecutive SCT recipients, severe bilateral ptosis was noticed or reported in six cases (five women and one man), all with acute graft-versus-host disease (aGVHD) and chronic graft-versus-host disease (cGVHD). On univariate analysis, both aGVHD (P=0.001) and cGVHD (P<0.001) were associated with post SCT ptosis, while a trend was shown for female sex (P=0.086). The median level of anti-acetylcholine receptor antibody was significantly higher in ptosis cases than controls with cGVHD (student's t-test, P=0.01). Antistriated muscle antibody was detected in three cases and was not significantly different from controls (Fisher's exact test, P=0.29). Tensilon tests were uniformly negative. However in five cases, single fibre electromyogram at frontalis muscle showed irregular recruitment effort, suggesting localized neuromuscular transmission defect reminiscent of ocular myasthenia gravis (MG). Two patients were observed, while three patients did not respond to mestinon or steroids treatment and one patient underwent aponeurosis advancement surgery. Transplant physicians and ophthalmologists should be aware of the problem of post SCT ptosis, which may be related to alloimmune causes of neuromuscular transmission block. Diagnosis can be difficult to confirm even with invasive SF-EMG testing. Most cases warrant conservative treatment due to chronicity, benign course and poor response to medication.

Co-occurrence of multiple sclerosis and myasthenia gravis in British Columbia

We describe eight patients with associated multiple sclerosis (MS) and myasthenia gravis (MG). Patients were less than 50 years old at the time of onset, and seven were female. The clinical course of both MS and MG was mild in most patients. To our knowledge, this represents the largest reported series. We provide further evidence for a nonrandom association of these two diseases and discuss common mechanisms of pathogenesis.

Immunotherapy of ocular myasthenia gravis reduces conversion to generalized myasthenia gravis

BACKGROUND

Several retrospective studies have suggested that immunotherapy, including prednisolone, azathioprine and thymectomy, reduces progression of ocular myasthenia gravis to generalized myasthenia gravis. This study examines the effect of immunotherapy on generalization rates in ocular myasthenia patients who are acetylcholine receptor (AChR) antibody-positive.

METHODS

Retrospective record review of 34 patients from three university-based hospitals with neurology and neuro-ophthalmology services in Australia. In all patients, positive AChR antibodies were recorded, the initial symptoms were purely ocular, and all had at least 2 years of follow-up. The patients who developed generalized myasthenia gravis were compared with those who remained purely ocular.

RESULTS

There were 21 patients who developed generalized myasthenia gravis. Of these 21, only 2 (9.5%) had received prior immunotherapy. Among the 13 patients whose symptoms remained purely ocular, 10 (76.9%) had received prior immunotherapy.

CONCLUSIONS

In this study, most of the patients who progressed from ocular myasthenia to generalized myasthenia had not received prior immunotherapy. This study adds weight to the call for a prospective trial of early immunotherapy in patients with ocular myasthenia.

Chiropractic care of a pediatric patient with myasthenia gravis

OBJECTIVE

To describe the chiropractic care of a pediatric patient with complaints associated with myasthenia gravis. Clinical features A 2-year-old girl was provided chiropractic care at the request and consent of her parents for complaints of ptosis and generalized muscle weakness (ie, lethargy), particularly in the lower extremities. Prior to entry into chiropractic management, magnetic resonance imaging of the brain and acetylcholine receptor antibody tests were performed with negative results. However, the Tensilon test was positive and the diagnosis of myasthenia gravis was made by a pediatrician and seconded by a medical neurologist. Intervention and outcome The patient was cared for with contact-specific, high-velocity, low-amplitude adjustments to sites of vertebral subluxation complexes in the upper cervical and sacral spine. The patient's response to care was positive and after 5 months of regular chiropractic treatment her symptoms abated completely.

CONCLUSION

There are indications that patients suffering from disorders "beyond low back pain" as presented in this case report may derive benefits from chiropractic intervention/management.

Childhood ocular myasthenia gravis

PURPOSE

To investigate the clinical manifestations and ocular findings in children with ocular myasthenia gravis (MG) that rarely have been reported in the literature.

DESIGN

Retrospective, noncomparative case series.

PARTICIPANTS

Twenty-four consecutive patients less than 15 years of age with ocular MG treated between June 1988 and July 2001.

METHODS

The medical records of 6 boys and 18 girls with ocular MG were reviewed retrospectively.

MAIN OUTCOME MEASURES

Alternate prism cover and uncover test, examination of ductions and versions, and visual acuity.

RESULTS

Mean age at onset was 38 months. Ptosis was found in 23 patients (96%), strabismus in 21 patients (88%), and amblyopia in 5 patients (21%). Exotropia combined with vertical heterotropia was the most frequent type of strabismus. Ductions were limited in 17 patients (71%), among whom supraduction or infraduction limitations were most frequently observed. Contrary to previous reports, medial rectus underaction was less common than lateral rectus underaction. Manifestations of strabismus and limitation of duction were variable and changed frequently during the follow-up period. The combined use of prednisone and pyridostigmine was found to be the predominant form of maintenance therapy, and ptosis was more responsive to drug therapy than limited ocular motility.

CONCLUSIONS

Children with ocular MG were found to have a high incidence of ptosis (96%) and exotropia and vertical hyperdeviation. Limitation on adduction was less common than that on abduction. First reported incidence of amblyopia (21%) and a relative nonresponsiveness of the limitation of eye movement to treatment were also noted.

Double trouble

A 78-year-old woman presented with vertical double vision. The Bielschowsky-Parks' three-step test suggested a left inferior rectus muscle paresis. Diagnostic testing confirmed the diagnosis of myasthenia gravis. Despite treatment with pyridostigmine bromide (mestinon) the diplopia persisted. She refused corticosteroid treatment and sought a second opinion, resulting in three unsuccessful strabismus surgeries to correct her ocular misalignment. The evaluation and management of ocular myasthenia gravis is reviewed and the appropriate timing of strabismus surgery is discussed.

A limited epidemiological study of seropositive myasthenia gravis in Tayside

Myasthenia gravis is an acquired disorder of the neuromuscular junction characterised by fatiguable weakness of the limbs, bulbar and facial muscles and may be complicated by respiratory muscle weakness and failure. One often confirms the diagnosis by a simple serological test looking for the presence of the nicotinic acetylcholine receptor antibody. However, seronegative myasthenia constitutes about 20% of cases and in the case of ocular myasthenia, only 50% will have the antibody. Therefore, the diagnosis can be less than straightforward especially if the patient presents with vague symptoms such as fatigue or presents to specialities other than neurology or ophthalmology. The fact that the diagnosis may prove to be challenging, compounded by the fact that the condition is relatively rare and that the antibody to the acetylcholine receptor is not always present, epidemiological data is often less than precise and indeed difficult to acquire. We felt it was necessary to try to establish the epidemiological data on seropositive myasthenia gravis in Tayside, (this has never been carried out) bearing in mind the above pitfalls, and see how the incidence compares with similar and previous studies.

Pseudomyasthenia resulting from a posterior carotid artery wall aneurysm: a novel presentation: case report

OBJECTIVE AND IMPORTANCE

Painful oculomotor palsy can result from enlargement or rupture of intracranial aneurysms. The IIIrd cranial nerve dysfunction in this setting, whether partial or complete, is usually fixed or progressive and is sometimes reversible with surgery. We report an unusual oculomotor manifestation of a posterior carotid artery wall aneurysm, which mimicked ocular myasthenia gravis.

CLINICAL PRESENTATION

A 47-year-old woman developed painless, intermittent, partial IIIrd cranial nerve palsy. She presented with isolated episodic left-sided ptosis, which initially suggested a metabolic or neuromuscular disorder. However, digital subtraction angiography revealed a left posterior carotid artery wall aneurysm, just proximal to the origin of the posterior communicating artery.

INTERVENTION

The aneurysm was successfully clipped via a pterional craniotomy. During surgery, the aneurysm was observed to be compressing the oculomotor nerve. The patient's symptoms resolved after the operation.

CONCLUSION

The variability of incomplete IIIrd cranial nerve deficits can present a diagnostic challenge, and the approach for patients with isolated IIIrd cranial nerve palsies remains controversial. Although intracranial aneurysms compressing the oculomotor nerve classically produce fixed or progressive IIIrd cranial nerve palsies with pupillary involvement, anatomic variations may result in atypical presentations. With the exception of patients who present with pupil-sparing but otherwise complete IIIrd cranial nerve palsy, clinicians should always consider an intracranial aneurysm when confronted with even subtle dysfunction of the oculomotor nerve.