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Carotid sinus syndrome masquerading as treatment resistant epilepsy
  1. Steve W Parry,
  2. Rose Anne Kenny
  1. University of Newcastle and Institute for the Health of the Elderly, Cardiovascular Investigation Unit, Royal Victoria Infirmary, Queen Victoria Road, Newcastle upon Tyne NE1 4LP, UK
  1. and requests for reprints to: Professor Kenny (email: R.A.Kenny{at}ncl.ac.uk)

Abstract

A 65 year old woman had a 12 year history of frequent, recurrent seizure-like episodes labelled as treatment resistant epilepsy after neurological evaluation and follow up and treatment with multiple antiepileptic medications. Carotid sinus massage provoked 5.6 seconds asystole with symptom reproduction, and she has remained symptom-free after permanent pacemaker implantation for her carotid sinus syndrome and withdrawal of antiepileptic medications.

  • syncope
  • carotid sinus
  • pacing
  • artificial
  • epilepsy

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Carotid sinus syndrome (CSS) was previously thought to be a relatively rare cause of syncope and presyncope in older subjects,1 2 but recent work has shown that the syndrome is more common than was previously thought,3 accounting for up to 20% of permanent pacemaker implants in centres with an interest in the condition.4 The diagnosis rests on the finding of more than three seconds cardiac asystole (cardioinhibitory subtype), 50 mm Hg fall in systolic blood pressure (vasodepressor subtype), or both (mixed subtype) during carotid sinus massage in association with symptoms of presyncope or syncope.2 3Permanent cardiac pacing for the cardioinhibitory and mixed subtypes provides dramatic relief of symptoms,5 6 but without a high level of suspicion, patients may be denied effective treatment. We report here on a woman with a 12 year history of “treatment resistant epilepsy” whose symptoms were relieved by pacing therapy for CSS.

Case report

A 65 year old woman was referred to our syncope facility by her neurologist with a history of at least one or two episodes of loss of consciousness per month. At her initial presentation 12 years previously, she had been troubled by at least twice weekly loss of consciousness lasting a few minutes, with a variable prodrome of light headedness and prompt full recovery, though often with headache and nausea for up to several hours afterwards. She had experienced urinary incontinence during one of these episodes. Several had resulted in injury, including a fall from a ladder with loss of consciousness due to the head injury sustained. The patient was otherwise well and there were no witness accounts of the “fits”. She was referred for specialist neurological assessment, during which clinical examination was normal, electroencephalography (EEG) on three occasions, including 24 hour ambulatory EEG, showed no diagnostic features and computed tomography of the head was unremarkable. The diagnosis of partial complex seizures was made, and over the succeeding 12 years, was treated with varying combinations of phenytoin (which caused symptomatic toxicity on two occasions, one resulting in grand mal seizures), sodium valproate, and carbamazepine with no improvement. The last three were eventually discontinued, and clonazepam and lamotrigine substituted with still no ease in symptoms. After two episodes during a flight, she was referred to our facility.

Additional medical history was of hypertension, and current medications included clonazepam, phenytoin, enalapril, and bendrofluazide. Examination, 12 lead surface and 24 hour ambulatory electrocardiographs, 40 minute head-up tilt test and initial carotid sinus massage were unremarkable. There was no evidence of orthostatic hypotension, and 24 hour ambulatory blood pressure monitoring showed a mean of 138/74 mm Hg on antihypertensives. Repeat carotid sinus massage in the head-up tilt position resulted in 5.6 seconds cardiac asystole, with a 102 mm Hg fall in systolic blood pressure, loss of consciousness and reproduction of usual symptoms. The patient was referred for permanent pacemaker implantation, and has remained symptom-free during the ensuing one year follow up period. After a 12 year gap, the patient has now also returned to driving. Antiepileptics were withdrawn gradually, with no recurrence of symptoms.

Learning points

  • Cardiovascular syncope may present as a convulsive disorder

  • Carotid sinus syndrome is more common than is generally appreciated and should be considered in all older patients presenting with loss of consciousness

  • A witness account is important in formulating a differential diagnosis

  • A label of “treatment resistance” should prompt full reappraisal of symptoms and diagnosis

Discussion

While other neurocardiovascular disorders, in particular vasovagal syncope, have been misdiagnosed as epilepsy previously7 8this is the first reported instance of CSS masquerading as an epileptiform disorder. In this case, our patient endured 12 years of frequent episodes of loss of consciousness, which severely impacted on her quality of life and deprived her of the ability to drive, as well as the marked adverse effects of over-medication. While the history was not characteristic of epilepsy, the combination of urinary incontinence and lack of a witness account conspired to direct the original diagnosis inappropriately. Unfortunately, alternative causes of syncope had not been entertained until late in this woman's illness.

CSS should be considered in all subjects with unexplained syncope, in particular where loss of consciousness is short lived, with little or no prodrome and prompt recovery. As in this case, the “classic” CSS history of syncope associated with head turning and tight collars9 is by no means essential; on the contrary, the majority of patients with CSS give no such history, often presenting with unexplained syncope, drop attacks, and falls.3 4 10 If carotid sinus massage is initially negative, repeat massage in the upright position may provide a diagnosis in over 30% of cases where initial supine carotid sinus massage is negative.11 Where seizure-like symptoms persist in a subject with poorly controlled epilepsy despite maximal antiepileptic therapy, particularly in the face of normal EEG, diagnostic re-evaluation for potential underlying cardiovascular disorders, in particular CSS, is mandatory.

Acknowledgments

Dr Parry is supported by a British Heart Foundation project grant.

References

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