Dengue Fever with Facial Palsy: A Rare Neurological Manifestation.

Sir,

Dengue fever is the second most common mosquito-borne disease affecting humans after malaria. Recently, virological characteristics of dengue viruses have been changing, resulting in widespread neurological complications which were found in 0.5%–21% of dengue cases. The central nervous system (CNS) complications comprise 95% of neurological complications, of which cranial neuritis is reported rarely in a few case reports. Few case reports are available regarding dengue-associated neuritis, such as brachial neuritis, long thoracic nerve palsy, phrenic, oculomotor, abducens, and peripheral facial palsy. We are describing a rare association of dengue fever causing facial palsy in a 65-year-old female.

Dengue made its debut as early as 1780 when Benjamin Rush described the condition as “break-bone fever.”[1] It is the second most common mosquito-borne disease affecting humans after malaria.[2] Worldwide, nearly 2.5 billion people continue to live at the risk of contracting the infection, whereas 50 million cases and 20,000 deaths are estimated to occur in 100 endemic countries.[1] Estimates suggest 500,000 cases of dengue hemorrhagic fever occur in the Asian countries.[3] The clinical presentation of dengue has a wide spectrum, ranging from mild clinical febrile illness to severe life-threatening conditions such as dengue hemorrhagic fever and dengue shock syndrome. Recently, virological characteristics of dengue viruses have been changing, resulting in widespread neurological complications.[4] It is caused by arboviruses which belong to the Flaviviridae family. Dengue virus one to four are the known serotypes of the virus of which two and three serotypes are mostly associated with neurological manifestations.[1] The association of dengue infection and neurological abnormalities was first described by Sanguansermsri et al. in 1976, in a patient presenting with encephalopathy.[5] Recently, virological characteristics of dengue viruses have been changing, resulting in widespread neurological complications, but their precise incidence rates remain undefined. Among these manifestations, encephalitis and encephalopathy are the most common neurological presentations.[6] We report a rare case of a 65-year-old female with right-sided facial weakness after dengue fever.

Our patient is a 65-year-old female, without any significant past medical illness presented with a history of generalized body ache followed after 5 days by acute-onset slurring of speech and deviation of the mouth to the left side. Family members also noticed that she was unable to close her right eye. There was no history of diplopia, dysphagia, limb weakness, or paresthesia. There was no history of fever, ear pain, discharge, or parotid enlargement. On presentation, she was conscious, alert and following verbal commands, was stable hemodynamically, and her physical examination was unremarkable except for lower motor neuron (LMN) type of right facial weakness [Supplementary Figure 1].

Magnetic resonance imaging of the brain with contrast study was normal. Electrophysiological evaluation of facial nerve revealed normal latency and reduced amplitude in a right facial nerve and normal peripheral nerve conduction study. The patient was incidentally detected to be having bicytopenia (hemoglobin – 6.6 g/dl, platelet count – 8000/mm3), elevated hematocrit (51%) without any history of bleeding manifestations. She was then evaluated for causes of thrombocytopenia and was found to have dengue immunoglobulin M antibody positive. Blood sugar level was normal, vasculitic markers were negative, and serum angiotensin-converting enzyme and serum ferritin levels were normal. Cerebrospinal fluid analysis was unremarkable. Bone marrow aspiration was normal and did not show evidence of hemophagocytosis. Other common causes of LMN facial palsy were ruled out by appropriate investigations.

The patient was treated with platelet transfusions, short course of steroid therapy, and other symptomatic management. Platelet counts increased to 65,000/mm3 by the time of discharge without any evidence of bleeding manifestations. After 4 weeks of follow-up, her facial nerve palsy showed a significant improvement along with normalization of platelet count and hematocrit.

Dengue has been a known clinical entity since 1780. Dengue infection has a wide spectrum of clinical presentation ranging from an asymptomatic subclinical state to most severe dengue fever with plasma leakage, bleeding manifestations, and multisystem involvement. In recent years, the virological characteristics of dengue viruses have been changing, and neurological manifestations of dengue infection have been increasingly reported. However, their incidence rates remain undefined.[4] Neurological complications can arise in any spectrum of dengue fever such as in dengue fever or in dengue hemorrhagic fever. Neurological manifestations occur more frequently in younger patients, during epidemics than in isolated cases and in dengue hemorrhagic fever/dengue shock syndrome.[7]

Although dengue had been regarded as a nonneurotropic virus, there are recent reports on neurotropism or neuroinvasion of the dengue virus, causing various CNS manifestations.[8] The neurological complications in dengue infection can be categorized into three groups based on the pathogenic mechanisms: (1) neurotropism leading to encephalitis, meningitis, myositis, and myelitis; (2) systemic complications resulting in encephalopathy, stroke, and hypokalemic paralysis; and (3) postinfectious immune-mediated acute disseminated encephalomyelitis, Guillain–Barre syndrome, and peripheral neuritis.[9]

CNS complications comprise 95% of neurological complications.[7] Cranial neuritis after dengue infection is rare. Few case reports are available regarding dengue-associated neuritis, such as brachial neuritis, long thoracic nerve palsy, phrenic, oculomotor, abducens, and peripheral facial palsy.[10]

Our patient had LMN type of right facial palsy within 1 week of dengue fever, which was confirmed by serological testing and after exclusion of other causes of LMN facial palsy with appropriate investigations. Only few case reports are available on LMN facial palsy due to dengue virus. There is a paucity of data on various aspects of neurological manifestations of dengue fever, and literature is lacking to suggest the true association of these atypical manifestations. Hence, dengue fever should be suspected in the endemic area during an outbreak in a patient with any undiagnosed neurologic syndrome.

In conclusion, dengue fever is a significant public health problem, especially in a tropical country like India. It is important to recognize the signs and symptoms at the earliest to reduce the mortality. Apart from typical manifestations, atypical presentations, especially neurological complications, are on rise, which make the diagnosis even more challenging and interesting for researchers. Continuous surveillance and timely interventions will minimize the complications, outbreak, and mortality. Dengue fever should be suspected in the endemic area during an outbreak in a patient with any undiagnosed neurologic syndrome, as literature regarding incidence and diagnosis are lacking. Our case also highlights the need for further detailed studies on neurologic manifestations in dengue fever so that measures can be taken for early diagnosis and prevention.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.

Right lower motor neuron facial palsy with a deviation of the mouth to the left side, flat nasolabial fold on the right side with Bell's phenomenon