Sweet taste loss in myasthenia gravis: more than a coincidence?

Taste disorder in a patient with invasive thymoma without myasthenia gravis: a rare case report

Taste disorder has been reported as a non-motor symptom caused by myasthenia gravis (MG)-related autoimmune mechanism. Taste disorder in some cases recovered along with MG treatment, such as thymothymectomy or immunosuppressive treatment. However, symptom of taste disorder in thymoma patients without MG is very rare. Here, we reported a case of invasive thymoma without MG which had concurrent taste disorder. The taste disorder was successfully treated with cyclosporine. A female in her seventies had an anterior mediastinal tumor of 78-mm in diameter and pleural dissemination. She also had taste disorder, limited to sweet taste, and pure red cell aplasia (PRCA). Symptoms and physical findings showed no feature of MG. Pre-operative blood examination revealed no elevation of anti-acetylcholine receptor antibody . Extended total thymothymectomy and resection of all detectable pleural disseminations was performed. Pathological examination showed type B3 thymoma. Clinical stage was Masaoka stage IVa. After operation, there was no improvement in taste disorder and PRCA. Six months after operation, cyclosporine was administered for PRCA. In parallel with gradual improvement of anemia, taste disorder also gradually improved. Three months after the first administration of cyclosporine, taste disorder had completely recovered. This is the first case of taste disorder without any myasthenic status, which recovered with immunosuppressive drug. Our case suggested the potency of immunosuppressive treatment for taste disorder associate with thymoma without MG.

An unusual presentation of thymoma: dysgeusia, ulcerative colitis, keratoconjunctivitis sicca, autoimmune retinopathy and myasthenia gravis

A 41-year-old female presented with dysgeusia, dry eyes, nyctalopia with progressive visual field constriction (due to autoimmune retinopathy) and gastrointestinal symptoms (due to ulcerative colitis). She was subsequently admitted to intensive care with a myasthenic crisis, and CT of the thorax demonstrated a thymoma.Following thymectomy and adjuvant radiotherapy, she has remained in complete remission from her ulcerative colitis and myasthenia gravis, her retinopathy has stabilised and there has been no thymoma recurrence over a 10-year postoperative period. There was a brief relapse of her dysgeusia (causing weight loss) and dry eye symptoms 3 years after her surgery, which resolved 8 months later. While the association of thymomas with paraneoplastic syndromes (PNS) is well established, it is unusual to present with multiple PNS, and some of these have only been documented in sparse case reports to date. Thymectomy played a crucial role in improvement and stabilisation of her PNS.

Dysgeusia: A review in the context of COVID-19

Background

Taste disorders in general, and dysgeusia in particular, are relatively common disorders that may be a sign of a more complex acute or chronic medical condition. During the COVID-19 pandemic, taste disorders have found their way into the realm of general as well as specialty dentistry, with significance in screening for patients who potentially may have the virus.

Types of Studies Reviewed

The authors searched electronic databases (PubMed, Embase, Web of Science, Google Scholar) for studies focused on dysgeusia, ageusia, and other taste disorders and their relationship to local and systemic causes.

Results

The authors found pertinent literature explaining the normal physiology of taste sensation, proposals for suggested new tastes, presence of gustatory receptors in remote tissues of the body, and etiology and pathophysiology of taste disorders, in addition to the valuable knowledge gained about gustatory disorders in the context of COVID-19. Along with olfactory disorders, taste disorders are one of the earliest suggestive symptoms of COVID-19 infection.

Conclusions

Gustatory disorders are the result of local or systemic etiology or both. Newer taste sensations, such as calcium and fat tastes, have been discovered, as well as taste receptors that are remote from the oropharyngeal area. Literature published during the COVID-19 pandemic to date reinforces the significance of early detection of potential patients with COVID-19 by means of screening for recent-onset taste disorders.

Practical Implications

Timely screening and identification of potential gustatory disorders are paramount for the dental care practitioner to aid in the early diagnosis of COVID-19 and other serious systemic disorders.

Sweet Taste Dysgeusia in a Patient with Indapamide-Related Hyponatremia: Case Report and Review of the Literature

Sweet taste dysgeusia is a rare symptom where patients experience all food as having a sweet taste. While its cause is still unknown, it has been increasingly reported in the setting of lung cancer and syndrome of inappropriate secretion of antidiuretic hormone-related hyponatremia. In this case report, we present what we believe to be the first case of sweet taste dysgeusia in a non-cancer context. We will briefly review and summarize all published cases describing this symptom and also reflect upon the nature of this condition focusing on the role of serum sodium levels in sweet taste receptor modulation.

Myasthenia Gravis With Thymoma, Manifesting as AChR-Ab-Positive, Distinct Bulbar Palsy Accompanied by Dysgeusia: A Case Series and Review of Literature

In this review, we summarized three cases of myasthenia gravis (MG) with taste disorder and describe their clinical features in detail. Three MG patients presented with significant bulbar palsy symptoms, high AChR-Ab titers, and negative MuSK-Ab, were diagnosed with thymoma. Furthermore, we observed that dysgeusia could manifest earlier than the occurrence of typical MG symptoms, even predict a MG relapse or a myasthenic crisis in the course of MG. We believe that dysgeusia is a non-motor symptom of MG, which especially exists in MG patients with thymoma and serious bulbar palsy. Therefore, being alert to this symptom may facilitate the early diagnosis of MG and judge the progress of the disease.

Correlation of HLA-DQ and TNF-α gene polymorphisms with ocular myasthenia gravis combined with thyroid-associated ophthalmopathy

The present study aims to explore the correlation of human leucocyte antigen (HLA)-DQ and tumour necrosis factor (TNF)-α gene polymorphisms with ocular myasthenia gravis (OMG) combined with thyroid-associated ophthalmopathy (TAO). From March 2009 to March 2015, 56 OMG patients complicated with TAO (OMG + TAO group), 134 patients diagnosed with OMG only (OMG group) and 236 healthy individuals (control group) were enrolled in the present study. PCR-sequence specific primer (PCR-SSP) was used for HLA-DQ genotyping and PCR-restriction fragment length polymorphism (PCR-RFLP) for TNF-α genotyping. ELISA kit was applied to detect acetylcholine receptor antibody (AchRAb) level and chemiluminescence immunoassay (CLIA) to measure thyroid-associated antibody (T-Ab) level. Logistic regression analysis was carried out to analyse the risk factors for OMG combined with TAO. DQA1*0103 showed lower frequency in the OMG group than in the control group. DQA1*0301 showed increased and DQB1*0601 showed decreased frequency in the OMG + TAO group. DQB1*0501 showed higher frequency in the OMG and OMG + TAO groups than in the control group. Patients carrying TNF-α -863C > A (CA + AA) might confront with greater risks of OMG combined with TAO. Frequency of DQA1*0103/*0301 and DQB1*0501/*0601, and TNF-α -863C > A, -238G > A and -308G > A were associated with the levels of AchRAb and T-Ab. TNF-α -863C > A (CA + AA) and high level of T-Ab were risk factors for OMG combined with TAO. Our results demonstrate that TNF-α -863 polymorphism is possibly correlated with the risk of OMG combined with TAO.

[A case of myasthenia gravis with transient taste disorders followed by aplastic anemia after thymectomy]

A 45-year-old man was admitted to our hospital because of taste disorders in March 2014. He exhibited cervical muscle weakness and left eye ptosis, which responded to Tensilon test, and was diagnosed with myasthenia gravis (MG). He developed aspiration pneumonia and myasthenic crisis, which was treated with intravenous immunoglobulin and steroid pulse therapy. All symptoms disappeared. Oral administration of prednisolone and tacrolimus was started. Chest CT revealed thymoma and extended thymectomy was performed in May 2014. In December 2014, seven months after the thymectomy, hematological examination showed pancytopenia including severe neutropenia. We diagnosed his illness as aplastic anemia (AA). Cyclosporine therapy with transfusion was administerd and led to reticulocyte count recovery. Since May 2015, hemoglobin recovery reached a blood transfusion free period. To our knowledge, this is the first case report with the patient supposed of relationship among taste disorders, AA and thymoma-associated MG.