Acute bilateral ptosis can be a hallmark of several serious neurological conditions. We present the first case of acute bilateral near-complete ptosis secondary to neuromyelitis optica spectrum disorder. We suggest that clinicians should consider this disorder among the differential diagnosis of acute bilateral ptosis, especially if there are other brainstem signs.
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A 71-year-old Samoan woman with a background of type 2 diabetes mellitus and hypertension awoke unable to open her eyes. Her family had noted a slight drooping of the right eyelid for a couple of days before. An ophthalmology registrar in the Emergency Department suspected myasthenia gravis; serum was sent for anti-acetylcholine receptor antibodies, and she was discharged with outpatient follow-up. Two days later she developed progressive dizziness ‘bolting round and round’, with nausea. Her eyes remained closed without fluctuation in the ptosis.
After a week of persistent symptoms, she re-presented to the Emergency Department. She had no speech or swallowing problems, limb weakness, headache, fevers or vomiting and no history of autoimmune disease.
On examination, there was complete right ptosis and near-complete left ptosis. Pupils and range of eye movements were normal. There was upbeat nystagmus in the primary position of gaze, increasing with upgaze. Orbicularis oculi strength was normal bilaterally, with no fatigability. The remaining cranial nerve examination and upper and lower limb tone, strength, coordination and reflexes were normal. Romberg test was negative.
Her full blood count, serum electrolytes and C reactive protein were normal. CT scan of head and CT angiogram of head and neck were normal. An edrophonium (Tensilon) test was negative.
We started aspirin, clopidogrel and atorvastatin for presumed brainstem infarction and admitted her. Cardiac monitoring was normal. MR scan of brain the next day (day 10 after onset) showed fluid-attenuated inversion recovery hyperintensity in the periaqueductal grey matter (figure 1). There were no diffusion-weighted imaging-positive lesions or contrast enhancement.
After admission, her temperature increased to 38.5°C. A septic screen was negative, including three sets of blood cultures, urine culture, chest X-ray and transthoracic echocardiogram. Cerebrospinal fluid examination showed a mononuclear pleocytosis with 208×106/L white blood cells (normal ≤4), 98% mononuclear cells, a mildly elevated protein of 0.66 g/L (normal 0.00–0.60), normal glucose, no oligoclonal bands and negative PCR tests for herpes simplex virus, varicella zoster virus and enterovirus. Serum antinuclear antibodies were low positive (titre 1:80) but antibodies to double-stranded DNA and extractable nuclear antigen were negative.
Other negative/normal tests included thyroid function tests, HIV, syphilis, quantiferon-GOLD, cerebrospinal fluid cytology and flow cytometry, serum anti-acetylcholine receptor antibodies and a CT scan of chest, abdomen and pelvis. We sent serum and cerebrospinal fluid to Oxford, England, for anti-GQ-1B antibodies, paraneoplastic antibody panel, anti-myelin oligodendrocyte glycoprotein antibodies and anti-aquaporin-4-IgG.
Our differential diagnoses included Bickerstaff's encephalitis, paraneoplastic syndrome and neuromyelitis optica spectrum disorder (NMOSD). We considered stroke to be unlikely given the lack of a diffusion-weighted imaging-positive lesions and the preceding ptosis noticed by her family.
Nine days after the admission, we started her on intravenous immunoglobulin 2 g per kg over 5 days for presumed antibody-mediated encephalitis. Her ptosis improved to the point she could just open the right eye.
After discharge, her immunology results returned: serum aquaporin-4-IgG was positive, suggesting NMOSD. Her other antibodies were negative, including anti-myelin oligodendrocyte glycoprotein, anti-GQ-1B and anti-Hu, Ri, Yo, Ma1, Ma2, CV2/CRMP5, amphiphysin, Sox-1, Zic-4 and anti-Tr.
At her 1-month follow-up, she was significantly improved with only mild residual bilateral ptosis (figure 2) and her dizziness had resolved. We started her on prednisone (60 mg/day starting dose) and azathioprine. At 3 months follow-up, she remains well with only mild persistent bilateral ptosis.
Acute bilateral ptosis can be a hallmark of several important neurological conditions. There are no previously reported cases of NMOSD causing acute bilateral ptosis. Lesions that cause bilateral ptosis can be localised (table 1) to the mesencephalic central caudal nucleus of the third nerve, bilateral third nerve involvement in the subarachnoid space or cavernous sinuses, the neuromuscular junction or levator palpebrae muscles.1
Our patient's pathology was most likely in the central caudal nucleus of the third nerve that supplies bilateral levator palpebral superioris muscles.2 This lies at the midline in the periaqueductal grey matter of the midbrain and corresponds to the MR brain scan abnormality.
Since NMOSD relapses can cause severe morbidity, early diagnosis and treatment are essential.3 Our patient fulfils all three requirements for the diagnosis of NMOSD set by the new international consensus diagnostic criteria, which require one core clinical characteristic, a positive test for serum anti-aquaporin-4-IgG, and exclusion of alternative diagnoses.4
An acute brainstem syndrome, distinct from the more typical area postrema syndrome, is included in the core clinical features of NMOSD. In a case series from Hong Kong, brainstem encephalitis was the initial presentation of NMOSD in up to 18% of patients.5 MR scan lesions surrounding the third ventricle and cerebral aqueduct are also characteristic of NMOSD, corresponding to high aquaporin-4 expression at these sites.6 ,7
The fever of 38.5°C is atypical for NMOSD and raises the possibility of alternative diagnoses including aseptic meningitis with a false positive serum anti-aquaporin-4-IgG. However, anti-aquaporin-4-IgG is highly specific for NMOSD: the Oxford laboratory's cell-based assay has a specificity of 99%.8 ,9 The absence of cerebrospinal fluid oligoclonal bands is consistent with this diagnosis and mild-to-moderate pleocytosis (range 6–380/µL (≤5)) may also occur in NMOSD.10
We present a previously unreported cause for acute bilateral ptosis, as well as a novel presentation of NMOSD. We suggest that NMOSD should be considered in the differential diagnosis of acute bilateral ptosis, especially if there are other brainstem signs.
Acute bilateral ptosis can result from a lesion of the central caudal nucleus of the oculomotor nerve located in the midbrain.
Neuromyelitis optica spectrum disorder should be considered in the differential diagnosis of an acute brainstem syndrome.
Serum anti-aquaporin-4 antibody is highly specific for the diagnosis of neuromyelitis optica spectrum disorder in the appropriate clinical context.
Contributors All authors were responsible for the clinical care of the patient described in the case report. The initial draft was written by PJ. All authors contributed to the final manuscript.
Competing interests None declared.
Patient consent Obtained.
Provenance and peer review Not commissioned; externally peer reviewed. This paper was reviewed by Kate Ahmad, Edinburgh, UK and Sarosh Irani, Oxford, UK.
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