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 Table of Contents  
Year : 2020  |  Volume : 5  |  Issue : 1  |  Page : 14-17

Herpes simplex virus encephalitis with a cause for pause: A case report

1 Internal Medicine, University of Iowa – Des Moines Internal Medicine Residency Program, UnityPoint Health – Des Moines, Des Moines, IA, USA
2 Department of Cardiology, UnityPoint Health, Des Moines, IA, USA

Date of Submission06-Aug-2020
Date of Decision15-Oct-2020
Date of Acceptance21-Nov-2020
Date of Web Publication28-Jan-2021

Correspondence Address:
Dr. Elizabeth Wendl
University of Iowa – Des Moines Internal Medicine Residency Program, 1415 Woodland Avenue, Suite 140, Des Moines, IA 50265
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/IJHR.IJHR_9_20

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We report a 61-year-old male who presented with recurrent syncopal episodes following 1 week of headaches, fevers, and malaise. Initial evaluation suggested sinus node dysfunction with a primary cardiac etiology; however, he was ultimately diagnosed with herpes simplex virus (HSV) encephalitis after suggestive findings on brain imaging and confirmation by positive HSV polymerase chain reaction in cerebrospinal fluid. The patient was treated medically and recovered without further intervention. Sinus arrest due to HSV encephalitis is a rare phenomenon that has been described infrequently in the literature. This case report highlights the importance of recognizing reversible causes of sinus node dysfunction to avoid unnecessary permanent pacemaker implantation. This study was approved by the Institutional Review Board of UnityPoint Health-Des Moines, USA (approval No. EX2020-014) on March 8, 2020.

Keywords: Arrhythmia, case report, encephalitis, herpes simplex virus, sinus node arrest, temporary cardiac pacing

How to cite this article:
Wendl E, Telles-Garcia N. Herpes simplex virus encephalitis with a cause for pause: A case report. Int J Heart Rhythm 2020;5:14-7

How to cite this URL:
Wendl E, Telles-Garcia N. Herpes simplex virus encephalitis with a cause for pause: A case report. Int J Heart Rhythm [serial online] 2020 [cited 2021 Sep 24];5:14-7. Available from: https://www.ijhronline.org/text.asp?2020/5/1/14/308168

  Introduction Top

Herpes simplex virus (HSV) encephalitis is the most common cause of viral encephalitis in the world, accounting for 20%–40% of all viral encephalitis cases with an annual incidence of 2–4/1,000,000.[1],[2] Very rarely, it has been associated with significant sinus node dysfunction; a recent literature review revealed five suspected cases reported.[3],[4],[5],[6],[7],[8]

In the current study, we described a case of HSV encephalitis as the likely cause of significant sinus node arrest.

  Case Report Top

A 61-year-old Caucasian male with a past medical history of hypertension presented to the emergency department at an outside hospital after recurrent syncopal episodes. For a week before admission, he had been experiencing headaches, fevers, generalized malaise, nausea, and a nonproductive cough. Admission vital signs were a temperature of 38.6°C, heart rate of 98 beats/min, and blood pressure of 164/89 mmHg with a Glasgow Coma Scale of 15. Initial workup including complete blood count, comprehensive metabolic panel, cardiac enzymes, and chest X-ray was unremarkable. Blood cultures, Epstein–Barr virus, and cytomegalovirus serologies were collected. He was admitted to the general medicine floor and started empirically on ceftriaxone. Two days after admission, the patient had a syncopal event, and a 10-s sinus pause was recorded on telemetry monitoring [Figure 1]. He was started on intravenous dopamine and transferred to the intensive care unit at our institution for consideration of permanent pacemaker implantation. On arrival, repeat laboratory data were remarkable for an elevated thyroid-stimulating hormone level of 29.56 U/mL (reference range: 0.27–4.20 U/mL) and free T4 of 9.0 pM (reference range: 11.6–21.9 pM). The patient experienced another 20-s pause with transient loss of consciousness without seizure-like activity, prompting temporary pacemaker placement. Intubation was not required. Additional cardiac workup included normal cardiac biomarkers, a 12-lead electrocardiogram demonstrating sinus rhythm with incomplete right bundle branch block [Figure 2], intermittent pauses on telemetry monitoring [Figure 3], and a transthoracic echocardiogram showing preserved left ventricular function.
Figure 1: Sinus arrest noted on telemetry monitoring at the outside hospital. The episode of asystole was recorded from 4:35:32 to 4:35:42 (10-s pause). The white rectangle on the right protects patient-identifying information

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Figure 2: Baseline electrocardiogram on arrival, demonstrating normal sinus rhythm and incomplete right bundle branch block (arrow)

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Figure 3: Telemetry monitoring demonstrating shorter episodes of sinus arrest (arrows), while the patient was in the intensive care unit before temporary pacemaker placement

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Due to persistent fever and worsening altered mental status, a lumbar puncture was performed. Cerebrospinal fluid (CSF) analysis was significant for 808 white blood cells (reference range: 0–10/mm3) with 99% lymphocytes and CSF viral film array positive for HSV-1 by a polymerase chain reaction. Computed tomography of the head demonstrated hypoattenuation in the right insular cortex and external capsule, and magnetic resonance imaging (MRI) of the brain showed abnormal signal within the right medial temporal lobe and right insular cortex suspicious for HSV encephalitis [Figure 4]. The patient was started on intravenous acyclovir and his clinical status improved after the 3rd day of therapy.
Figure 4: Brain magnetic resonance imaging demonstrating hyperintense fluid-attenuated inversion recovery signal in the medial right temporal lobe extending into the right insular cortex (arrow), consistent with herpes simplex virus encephalitis

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Sinus node dysfunction persisted for approximately 24 h and improved after initiation of acyclovir with concurrent clinical improvement. The temporary pacemaker was removed after sinus pauses were absent for 72 h. He was discharged home after completing 14 days of intravenous acyclovir and was started on levothyroxine for his newly diagnosed hypothyroidism. Repeat lumbar puncture and repeat brain MRI were not performed due to the resolution of altered mental status and clinical recovery. Of note, we did not receive written patient consent; however, we went through the appropriate institutional review board review process of UnityPoint Health-Des Moines, USA (approval No. EX2020-014, approved on March 8, 2020) and obtained separate permission for Waiver of Patient Consent at the time of case report approval.

  Discussion Top

HSV encephalitis is most commonly caused by HSV-1, with fewer cases caused by HSV-2. Classic signs and symptoms include confusion or altered mental status, headaches, nausea, vomiting, and less commonly focal neurologic deficits. Nearly 60%–90% of older adults are seropositive for HSV-1, and it is unclear if encephalitis is caused by latent infection or a new primary infection.[1] This illness can be devastating, carrying an 80% mortality if untreated and 20%–30% mortality with treatment; only 50% of treated patients return to their baseline level of function.[3] Diagnosis can be achieved several ways – lumbar puncture will demonstrate lymphocytic pleocytosis, increased CSF protein, and normal glucose. CSF polymerase chain reaction for HSV-1 and HSV-2 has a sensitivity of >95% and specificity of >99%.[1] Brain MRI will show inflammatory edema in the medial temporal, inferior frontal, and insular regions that is relatively specific for HSV encephalitis or autoimmune encephalitis.[1],[2] Treatment is typically 14–21 days of intravenous acyclovir.[1]

Many of the known complications of HSV encephalitis are neurologic, i.e., altered mental status, seizures, and cerebral edema. Arrhythmias, sinus node dysfunction, and sinus pauses or arrest are described with less frequency. Potential mechanisms include a direct cytotoxic effect on the myocardium, supported by case reports of HSV-proven myocarditis,[3] versus a centrally mediated effect, supported by the fact that other diseases affecting the temporal lobe are associated with arrhythmias.[4] There have been reports of cardiac arrhythmias or asystole in patients with stroke or seizure affecting the temporal lobes, as well as sinus node dysfunction in cases of autoimmune encephalitis that resolved after treatment.[4],[9] It is proposed that the cardiovascular system is regulated by a central autonomic network including the insular cortex, anterior cingulate gyrus, and amygdala. As HSV encephalitis often affects the insular cortex, it can reduce sympathetic tone and increase autonomic instability. This leads to exaggerated sinus node pauses or arrest, especially with lesions on the right side.[5],[6] In addition to sinus node dysfunction, arrhythmias such as polymorphic ventricular tachycardia have also been described in patients with HSV encephalitis.[5]

Literature search revealed five cases of HSV encephalitis causing sinus node dysfunction reported after 1986, with the longest pause recorded at 10 s.[4],[5],[6],[7],[8],[10] Our patient had prolonged pauses for up to 20 s, and the duration may have been influenced by his newly diagnosed hypothyroidism, which predisposes to bradyarrhythmias. To our knowledge, this case demonstrates the longest sinus node arrest reported that is associated with HSV encephalitis. In all identified cases, including this patient, treatment of the underlying HSV encephalitis with acyclovir led to resolution of the sinus pauses; no patients received a permanent pacemaker, and only one received an implantable cardiac defibrillator for secondary prevention of polymorphic ventricular tachycardia that did not recur after treatment.[6]

This case demonstrates the rare phenomenon of sinus node arrest requiring a temporary pacemaker caused by HSV encephalitis that subsequently resolved with treatment of the underlying condition. It highlights the importance of exploring secondary causes of sinus node dysfunction, as many of these patients would have received permanent pacemakers if not for their febrile illness postponing the procedure. It also suggests that any patient diagnosed with HSV encephalitis (or potentially any temporal lobe pathology) should be on continuous cardiac monitoring to monitor for this rare but potentially life-threatening complication.

Institutional review board statement

This study was approved by the Institutional Review Board of UnityPoint Health-Des Moines, USA (approval No. EX2020-014) on March 8, 2020.

Declaration of patient consent

This study qualified for exempt status under the following category per (45 CFR 46.104)(21CFR56.104(d)): Category 4: Secondary research for which consent is not required: (ii) Information is recorded so subjects cannot be identified (directly or indirectly/linked), the investigator does not contact subjects and will not reidentify subjects.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Rabinstein AA. Herpes virus encephalitis in adults: Current knowledge and old myths. Neurol Clin 2017;35:695-705.  Back to cited text no. 1
Stahl JP. Update on HSV and VZV infections of the brain. Rev Neurol (Paris) 2019;175:442-4.  Back to cited text no. 2
Yamamoto T, Kenzaka T, Matsumoto M, Nishio R, Kawasaki S, Akita H. A case report of myocarditis combined with hepatitis caused by herpes simplex virus. BMC Cardiovasc Disord 2018;18:134.  Back to cited text no. 3
Smith BK, Cook MJ, Prior DL. Sinus node arrest secondary to HSV encephalitis. J Clin Neurosci 2008;15:1053-6.  Back to cited text no. 4
Nicol PP, Talarmin JP, Joseph T. Herpes simplex encephalitis, an unusual cause of sinus node dysfunction: Case report and literature review. Int J Clin Cardiol 2015;2:042.  Back to cited text no. 5
Huemer M, Boldt LH, Wutzler A, Parwani A, Rolf S, Blaschke D, et al. Polymorphic ventricular tachycardia in a patient with herpes encephalitis. J Clin Neurosci 2012;19:483-4.  Back to cited text no. 6
Kikumoto M, Nagai M, Ohshita T, Toko M, Kato M, Dote K, Yamashita H. Insular cortex lesion and autonomic instability in a herpes simplex virus encephalitis patient. J Neurovirol 2018;24:649-51.  Back to cited text no. 7
Alsolaiman MM, Alsolaiman F, Bassas S, Amin DK. Viral encephalitis associated with reversible asystole due to sinoatrial arrest. South Med J 2001;94:540-1.  Back to cited text no. 8
Amor MM, Eltawansy SA, Osofsky J, Holland N. Recurrent sinus pauses: An atypical presentation of temporal lobe epilepsy. Case Rep Critical Care 2014;2014:918247.  Back to cited text no. 9
Saffran L, Goldner BG, Adler H, Feingold BD, Feingold RM, Latcha S, et al. Asystole associated with herpes simplex encephalitis. J Invasive Cardiol 1995;7:152-5.  Back to cited text no. 10


  [Figure 1], [Figure 2], [Figure 3], [Figure 4]


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