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Introduction

Primary Sjogren syndrome (pSS) is a systemic inflammatory autoimmune disease of unknown etiology that is characterized by salivary and lacrimal gland dysfunction due to infiltration of autoreactive lymphocytes [1]. Patients with pSS can display various types of extra-glandular involvement due to autoimmunity, including peripheral neuropathy, bronchitis, pneumonitis, and interstitial nephritis [2]. Here, we describe a rare case of pSS that presented as peripheral neuropathy in the bilateral facial nerves.

Case Presentation

An 83-year-old woman was admitted to our hospital complaining of difficulty closing her right eye. Four weeks before this admission, she had visited a neurologist after noticing disordered closure of the left eye and the mouth, and was diagnosed with left peripheral facial nerve paralysis. The neurologist prescribed 30 mg daily of prednisolone and 1000 mg daily of acyclovir. The prednisolone was tapered at a two-day interval and discontinued after 8 days. She felt that her facial palsy had partially improved. When she presented at our hospital with the right eye closure disorder, she was admitted for further investigation and treatment.

Her physician had prescribed 5 mg daily of amlodipine, 0.5 μg daily of alfacalcidol, 35 mg weekly of alendronate, 90 mg daily of bethanechol chloride, and 90 mg daily of urapidil for hypertension, osteoporosis and urinary disturbance. She had been diagnosed 9 years previously with autoimmune hepatitis that was treated with prednisolone. Prednisolone was tapered and discontinued 8 years previously and there had been no further relapse of autoimmune hepatitis.

On admission, her heart rate was 77 bpm, blood pressure was 138/65 mmHg, body temperature was 36.8 °C, and oxygen saturation was 99%. There was bilateral absence of wrinkles on the skin of the forehead and narrowing of the palpebral fissures. Mild bilateral hearing loss in the high frequency rage was considered mild presbycusis. There were no blisters or redness on the skin of the face or in the ear canals, there was drooping of the corners of the mouth, and the cervical lymph nodes were not palpable. Cranial nerve examinations were otherwise normal, and the patient was diagnosed with bilateral peripheral facial nerve paralysis. Saliva in the oral cavity was viscous, and saliva outflow from the large salivary glands and labial glands was poor. Schirmer’s test I measure was 7 mm on the right side and 11 mm wetting per 5 minutes on the left side. Corneal fluorescent staining was positive.

Laboratory values were as follows: angiotensin-converting enzyme, 15.4 IU/l; IgG, 1237 mg/dl; IgA, 410 mg/dl; IgM, 34 mg/dl; C3, 120 mg/dl; C4, 29 mg/dl; anti-nuclear antibody negative; anti-SS-A antibody, 551 U/ml; anti-SS-B antibody, <0.1 U/ml; MPO-ANCA, <0.5 U/ml; PR3-ANCA, <0.5 U/ml; and anti-acetylcholine receptor antibody negative. There was no evidence of antibodies to Borrelia burgdorferi. Erythrocyte sedimentation rate and serum C-reactive protein were within normal ranges. Immunoglobulin M (IgM) antibody for varicella zoster virus and IgM antibody for herpes simplex virus were negative. The protein level and cell count in cerebrospinal fluid were within normal ranges. MRI of the brain revealed no significant abnormal signal intensities and excluded lesions in the 5^th, 7^th, and 8^th cranial nerves. Chest CT revealed no significant abnormality.

We performed minor salivary gland biopsy to identify the cause of the elevated anti-SS-A antibody level. Histopathological examination of the biopsy tissue revealed mild to moderate atrophy of serous and mucous glands with marked infiltration of small round cells and lymphocytes around the salivary duct, and inconspicuous fibrosis. There were two foci of >50 lymphocytes within 3 mm² (Figure 1) that were classified as grade 4 on the Greenspan system. Primary Sjogren syndrome was diagnosed based on these findings.

We prescribed 30 mg daily of prednisolone, which was tapered every two days, and then switched to 10 mg every other day of prednisolone and 3 mg daily of tacrolimus. The bilateral peripheral facial nerve paralysis ameliorated gradually and had almost disappeared after 3 months.

Discussion

We described a rare case of peripheral neuropathy of the bilateral facial nerves with coexistence of pSS. The peripheral neuropathy is extra-glandular involvement of pSS, and is classified as polyneuropathy, mononeuropathy, mononeuropathy multiplex, polyradiculopathy, or cranial neuropathy according to the spatial distribution [3]. Cranial neuropathy is a less common type that generally manifests as trigeminal or facial nerve neuropathy, and is bilateral in very rare cases. To the best of our knowledge, only three cases of bilateral facial nerve neuropathy complicated with pSS have been reported previously [4-6].

Bilateral facial nerve neuropathy is also a rare condition among the general population, being reported in 0.3%–2% cases of facial nerve neuropathy [7]. Of these, Bell’s palsy is the most common. Other causes of bilateral facial paralysis include Lyme disease, Möbius syndrome, tumor, bilateral temporal bone fracture, Guillain–Barré syndrome, central nervous system lymphoma, and HIV infection [7]. We ruled out these conditions by the clinical features, serological findings, and imaging examinations.

The present diagnosis of pSS was confirmed by the histopathological findings of minor salivary gland biopsy because the xerophthalmia and xerostomia were too mild to enable a diagnosis of pSS with only the physical and immunological findings. Xerophthalmia and xerostomia can be induced by peripheral neuropathy in the facial nerve via the absence of stimulation to the salivary and lachrymal glands by the facial nerve. Thus, cautious consideration is required in diagnosing pSS with facial paralysis.

Considering the false positivity of xerophthalmia and xerostomia, the coexistence of pSS and bilateral facial palsy may go underdiagnosed.

In the presence of bilateral facial nerve neuropathy, it may be very difficult to diagnose pSS as an underlying disease unless histological investigation of minor salivary glands is performed, along with immunological examinations such as hypergammaglobulinemia, anti-SS-A and anti-SS-B antibodies, and rheumatoid factor. These serological and histological examinations are rarely performed in clinical practice for the investigation of facial nerve neuropathy.

Patient Consent

The patient provided written informed consent to the publication of her personal data.

Ethical Statement

Ethical approval was not required for this Case Report.

Funding

The authors received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

Conflict of Interest

None