Ocular myasthenia gravis and inflammatory bowel disease: a case report and literature review

Myasthenia gravis has been reported to be associated with both ulcerative colitis (UC) and Crohn’s disease (CD).^1–3 The link between inflammatory bowel disease (IBD) and myasthenia gravis (MG) is thought to be related to the production of autoantibodies.¹ Myasthenia gravis is also associated with other autoimmune diseases including alopecia, lichen planus, vitiligo, and systemic lupus erythematosus.⁴

Similarly, IBD frequently presents with other autoimmune disorders. One study demonstrated a 9.4% prevalence of autoimmune disorders in patients with UC including sclerosing cholangitis, thyroid disorders, vitiligo, insulin dependent diabetes mellitus, thyroid disease, pernicious anaemia, scleroderma, and seropositive rheumatoid arthritis.^4,5 Despite the association between MG and other autoimmune disorders, there are relatively few reports of ocular findings as the presenting sign of MG in patients with IBD.

Case report

A 21 year old African-American male, with a medical history of biopsy proved ulcerative colitis diagnosed in 1995, focal segmental glomerular sclerosis determined by renal biopsy in 1995, and primary sclerosing cholangitis determined by liver biopsy in 2000 presented to the neuro-ophthalmology service with complaints of binocular diplopia and ptosis of the left upper eyelid. Both the diplopia and the ptosis were better in the morning and worsened during the course of the day. His ulcerative colitis had been in remission for the past 5 years without medication.

Best corrected visual acuity was 20/25 in each eye. The external examination revealed ptosis of the left upper eyelid that worsened in sustained upgaze. He had limited extraocular motility in all fields of gaze (Fig 1). The remainder of the neuro-ophthalmic examination was normal and he had no difficulty with speech or swallowing.

Figure 1.

External photograph shows ptosis of the left upper eyelid, restriction of all extraocular movements of the left eye, and an elevation and adduction deficit of the right eye.

Laboratory evaluation revealed a positive acetylcholine receptor antibody and normal thyroid function studies. There was no evidence of a thymic mass on magnetic resonance imaging of the chest.

The patient returned to the emergency room 1 week later with difficulty swallowing and shortness of breath. He was hospitalised for plasmapheresis and upon discharge treated with imuran, prednisone, and mestinon. One month later his ptosis resolved and his extraocular motility was normal.

Comment

Autoimmune disorders, including MG, occur more frequently in UC than in CD.³ It is not clear how many other cases of IBD manifested with ocular presentations as the initial finding of MG as in our case report. Our literature review revealed only one other purely ocular presentation of myasthenia associated with ulcerative colitis; however, details of the ocular examination were not included.⁵ Another report, of a 21 year old woman with a 3 year history of Crohn’s disease, documented diplopia and unilateral ptosis as the initial findings of MG.³ She was found to have acetylcholine receptor antibodies and her ocular findings improved with pyridostigmine.

Because of the relatively few reports of ocular myasthenia in patients with IBD we reviewed the English literature and found four additional reports of MG in patients with IBD. Based on these four reports and the three (including the present report) with ocular MG in patients with IBD (Table 1), the mean duration of IBD before the diagnosis of MG was 10 years.

Table 1.

Previous reports of myasthenia gravis occurring in patients with inflammatory bowel disease

Reference	Age (years)	Sex	IBD	Duration of IBD before diagnosis of MG (years)	AchR antibody reactivity
Miller 19715	35	Male	UC	13	Unknown
Tan 19744	38	Male	UC	12	Unknown
Martin et al, 19911	63	Male	CD	15	Positive
Gower-Rousseau et al, 19938	27	Female	UC	10	Positive
Finnie et al, 19943	21	Female	CD	3	Positive
Lossos et al, 19959	11	Male	CD	9	Unknown
Present report	21	Male	UC	7	Positive

IBD = inflammatory bowel disease, MG = myasthenia gravis, AchR = acetylcholine receptor, UC = ulcerative colitis, CD = Crohn’s disease.

Autoimmune dysregulation is the central defect in both MG and IBD. Both IBD and MG may be associated with an elevated carcinoembryonic antigen (CEA) and decreased peripheral lymphocyte counts that subsequently normalise following thymectomy.⁶ Some studies have shown abnormal thymic involution and the presence of an abnormal ratio of T suppressor to T helper cells in both MG and UC, while others have noted a decline in suppressor T cells and an increase in immature helper T cells suggesting migration without normal maturation.^2,7

The immunological link between MG and IBD is highlighted by two reports of patients undergoing surgical treatment. One report of a patient with both MG and CD documented improvement in perineal and perianal disease following thymectomy for severe uncontrolled MG.³ Another patient with both MG and UC demonstrated regression of the myasthenia following proctolectomy.⁸

Although the simultaneous occurrence of these two autoimmune disorders is uncommon, it is important to understand that ocular findings may be the initial manifestation of MG in patients with IBD.