Recurrent episodes of falls and amnestic confusional states as diagnostic challenge in the elderly

Abstract

New-onset paroxysmal events in patients over 60 years of age are often diagnostically challenging owing to atypical presentation. Recurrent falls and transient states of confusion are especially common in the elderly population, yet their causes often remain undiagnosed due to concomitant cognitive deficits and motor impairments. We present an elderly patient with newly occurring ‘blackouts’ without obvious triggers and transient states of confusion for which he was amnestic. All neurological exams including brain MRI scan and routine electroencephalography (EEG) were normal. Long-term ECG monitoring using an event recorder captured an asystole during a habitual episode, leading to the diagnosis of syncope and pacemaker implantation. A subsequent video EEG monitoring performed due to ongoing unexplained confusional states revealed both bradycardia and long-lasting confusional states to be caused by unrecognised temporal lobe seizures. Ictal video EEG monitoring may play a crucial role in establishing a diagnosis of atypical temporal lobe seizures in the elderly.

Background

Falls with loss of consciousness as well as transient states of confusion are common in elderly population and may have various aetiologies. Some of those patients will have epilepsy, which can be difficult to ascertain. Epilepsy in individuals over 60 years of age can represent a diagnostic challenge for treating clinicians owing to its atypical presentation, concomitant cognitive impairment and often non-specific findings in medical tests. About 30% of elderly patients with confirmed epilepsy had not been considered to have this diagnosis at first evaluation¹ and probably those patients, if not been referred to an epileptologist, remain undiagnosed.² We report a case of an elderly patient suffering from syncopal events due to recurrent asystole as well as transient states of confusion with memory impairment that were both caused by unrecognised temporal lobe seizures.

Case presentation

A 63-year-old man, a retired lawyer, without neurological and psychiatric history, was admitted to video-EEG monitoring for differential diagnosis of paroxysmal spells characterised by sudden transient loss of consciousness with falls and occasional states of confusion emerging during last 5 years. The patient denied having any specific prodromal signs or triggers except for an occasional ‘slack feeling’ in the lower abdomen a few seconds prior to the fainting episodes that he named ‘blackouts’. Due to the low frequency of the episodes (about 3–5 times per year), only few events had been witnessed. According to observers, the patient suddenly collapsed while standing and became unresponsive for approximately 2 min. He recovered spontaneously but remained disoriented for about half an hour afterwards. No abnormal motor activity was witnessed, and he experienced no incontinence.

In addition, the patient reported of episodes of disorientation. He felt confused and ‘dreamy’ up to several hours during which he had abnormal behaviour yet had retrograde memory loss with slow recovery over many hours.

His medical and neurological examination was normal. High-resolution 3T MRI brain imaging showed age-appropriate normal finding. Repeatedly performed ECG and electroencephalography (EEG) recordings did not reveal any abnormalities. Due to the normal workup, his cardiologist attributed the recurrent falls to be a cardiac event and arranged implantation of an event recorder (Medtronic, Reveal XT 9529/9539). After one of the habitual events had been captured by the recorder, the ECG analysis revealed an asystole over 35 s (figure 1). This led to establishing a diagnosis of cardiac syncope and implantation of a heart pacemaker in DDI (dual chamber pacing and sensing, but inhibited mode only) mode (Medtronic, Ensura DR MRI Sure Scan EN1DR01). The cardiologist considered the syncopes to be controlled and certified the patient to be fit to drive again. Whereas falls were no longer observed, transient confusional states continued, and the consulted neurologist suggested an additional video-EEG examination to rule out other possible reasons of these episodes.

Figure 1.

The patient’s ECG tracing during a habitual blackout event captured by an event recorder, demonstrating the asystole period over 35 s.

During a 72-hour video-EEG monitoring with EEG electrodes placed according to the international 10–20 system, the entire interictal EEG did not show any abnormality, neither epileptic discharges nor regional slowing. Following mild sleep deprivation, an epileptic autonomic seizure was recorded during a left temporal ictal EEG pattern (figure 2). Concomitant ECG registered an early ictal slowing of the heart rate resulting in activation of the cardiac pacemaker at the 55/min intervention frequency for a period of 27 s when spontaneous sinus rhythm in the normal frequency rate re-established. The seizure semiology was objectively characterised only by the ictal bradycardia, accompanied by a slight change in facial expression, neither with motor symptoms like automatisms or elementary motor signs nor with any other localising or lateralising marks with the possible exception of the autonomic sign of ictal bradycardia that has been related to the left temporo-insular origin.³

Figure 2.

Ictal scalp EEG tracing with a longitudinal transverse bipolar montage. The top arrows mark the rhythmical left temporal activity indicating the EEG onset and the end of the seizure. Note the ictal slowing of heart beat followed by the onset of pacemaker activity and the spontaneous recovery of the sinus rhythm postictal (bottom arrows).

Whereas this event remained unnoticed by both patient and monitoring team until the EEG was retrospectively analysed, the patient was found to be disoriented to time by the visiting nurse 10 min later. He appeared helpless and irritated. He suspected he might have been given a drug as he felt ‘strange’. When tested, he was found disoriented to the situation, repeatedly asking why he was in the hospital. He had a sense of recognition yet feeling unclear as to how he knew technicians and his neighbour patient. He could not recall a visit of his wife on the previous day and even his wife’s name. He kept repeating the same sentences: ‘I don’t understand why I am here. His [another patient’s] face seems familiar to me. Am I here voluntarily?’ (video 1). This amnestic episode persisted for 1 hour after the ictal event until the patient returned to his baseline normal neurological state. Language and speech production were unimpaired during this episode, and there was no evidence of hallucinations or delusions.

Video 1.

Download video file ^{(7.8MB, mp4)}

DOI: 10.1136/bcr-2018-228842.video01

Postictal testing of the patient.

Outcome and follow-up

Based on the diagnosis of focal epilepsy, antiepileptic drug treatment with pregabalin was established. So far, the patient has remained asymptomatic within a follow-up period of 8 months. He was instructed not to operate a vehicle.

Discussion

This patient suffered from falls and prolonged episodes of confusion and memory loss as the only manifestations of the unrecognised epileptic seizures. In the absence of pathologies in the interictal EEG and brain imaging and lacking typical features of epileptic seizures, it took almost 5 years to establish the accurate diagnosis of temporal lobe epilepsy. Isolated long-term ECG monitoring had erroneously attributed a documented asystole to a primary cardiac origin. The correct diagnosis required an ictal video-EEG recording.

Epilepsy is often underdiagnosed in patients over 60 years of age. Certain ageing-related comorbidities like hypertension, cognitive impairment, transient ischemic attack (TIA) and cardiac disease may be mistakenly considered to underlie symptoms in an elderly patient with new-onset epilepsy. However, about one-third of elderly patients are incorrectly diagnosed with epilepsy while having another explanation of their complaints.¹ The accurate diagnosis crucially depends on reporting of the spell by the patient himself or by a witness. Since the manifestations of epileptic seizures can vary largely and have many imitators, many paroxysmal events cannot be distinguished based on history only. In elderly patients, the frequent coexistence of cognitive deficits makes obtaining an accurate history even more difficult whereas witnessed records are also less common.⁴

Seizures in elderly have been consistently found to be mostly focal seizures with impaired awareness,⁵ followed sometimes by prolonged postictal confusion.^{6 7} Auras are less often reported or can be absent, and symptoms and signs can be atypical or non-specific.^{8 9} If falls with transient loss of consciousness can be ascertained, the primary clinical suspicion refers usually to two main differential diagnoses: syncope and epilepsy. As cardiac diseases and in particular disorders affecting the heart conduction system are frequent in the elderly, their presence does not rule out a possible coexistent epilepsy and a primary epileptic genesis of their falls. Ictal asystole is a rare yet potentially dangerous autonomic manifestation of epileptic seizures that affects about 0.3% of epilepsy patients without cardiac comorbidities.^{10 11} Given its typical manifestation as a sudden loss of tone, ictal asystole is misrecognised due to its clinical presentation as syncope even if occurring only during seizures. Holter monitoring may record a corresponding sinus arrest that frequently leads to a cardiac pacemaker insertion. Both pacemaker implantation and initiation of antiepileptic medication may reduce the frequency of seizure-associated falls and subsequent trauma.¹² Moreover, the ictal asystole observed here may additionally bear an increased risk for the later development of SUDEP,¹³ supporting again both the antiepileptic treatment and possibly a pacemaker implantation.

Similarly, transient states of confusion may represent a manifestation of focal epileptic seizures; nevertheless, other potential reasons of transitory confusion as dementia, drug intoxication, sleep disorders, some metabolic disturbances and transient global amnesia have to be also considered. Transient epileptic amnesia (TEA) presents with amnestic attacks of epileptic nature in patients in late-middle and old age.¹⁴ TEA shares many clinical features with transient global amnesia involving disorientation and repetitive questioning¹⁵ but is characterised by more frequent recurrence and shorter duration of the attacks, usually 30–60 min, though episodes occasionally last for several hours.^16–18 Basically, TEA episodes have similar duration as postictal motor impairment¹⁹ or postictal deficit in diverse cognitive domains.²⁰ TEA has been considered to be related to temporal lobe epilepsy; however, routine interictal EEG recording does not show EEG abnormalities in two-thirds of TEA cases.^{21 22} In the presented case, even continuous interictal EEG recordings did not provide evidence of underlying epilepsy that could only be identified by the ictal recording of a left temporal seizure pattern.

TEA is strongly associated with prominent persistent (interictal) cognitive impairment with main focus on memory loss for personally experienced events (autobiographical amnesia), rapid fading of newly acquired memories over a period of days to weeks (accelerated long-term forgetting) and difficulties with spatial navigation (topographical amnesia).^21–23 In the elderly, such memory impairments may cause the suspicion of a mild cognitive deficit leading to dementia. In the case reported here, transient epileptic memory impairment was a clear postictal sign during the hour following a left temporal, otherwise non-recognised seizure.

TEA attacks have been reported to be well manageable with anticonvulsant medication, often in monotherapy.^{16 21} Unfortunately, treatment is often delayed due to misdiagnosis of patients as having dementia, psychogenic amnesic states or the above-mentioned transient global amnesia. The accurate reviewing the history of attacks with attention to the possible co-occurrence of additional epilepsy marks such as autonomic signs may help clinicians to recognise the epileptic nature of the episodes. It remains unclear if anticonvulsant treatment improves interictal cognitive deficit or whether its delay worsens it. There are few controversial publications reporting memory improvement as well as persistence of memory problems even once the amnestic attacks have ceased.¹⁴

Elderly people have the highest incidence of developing new-onset epilepsy, which is estimated as 40 per 100 000 at 60 years old and rising dramatically to 139 per 100 000 at 70 years old.^{24 25} As the geriatric population continues to grow worldwide, epilepsy will remain a spread complex clinical condition requiring medical specialists to give thoughtful consideration to potential causes and optimal therapeutic intervention in elderly patients also regarding possible comorbidities. According to the published records, people over 60 years of age with new-onset epilepsy have a better prognosis for seizure control when using appropriate anticonvulsant treatment compared with younger population.^{26 27} Educational efforts between healthcare professionals should be made to improve awareness of such well-treatable epileptic conditions and facilitate the establishing a correct diagnosis in elderly patients to ensure high-quality care in this vulnerable population.

Learning points.

• New-onset epilepsy in elderly population can be challenging to diagnose due to an atypical clinical presentation including periods of postictal confusion and falls.

• Asystole may explain falls yet do not always reveal the underlying aetiology.

• Normal MRI and routine interictal EEG do not rule out a focal epilepsy.

• Transient states of confusion and memory loss in elderly patients need an accurate diagnostic differentiation since the epilepsy associated events can be well treatable.