Epileptiform Activity During Transient Focal Neurologic Episodes in Cerebral Amyloid Angiopathy

PRACTICAL IMPLICATIONS

In older patients with recurrent unexplained focal neurologic episodes, an EEG and brain MRI may reveal that they are a treatable manifestation of CAA.

Transient focal neurologic episodes (TFNEs) constitute a paroxysmal clinical manifestation of cerebral amyloid angiopathy (CAA), an age-related small vessel disease characterized by deposition of β-amyloid protein in the walls of cortical and leptomeningeal arteries.

Although the most dramatic clinical presentation of CAA is lobar intracerebral hemorrhage, cerebral microbleeds (CMBs), superficial siderosis, and convexity subarachnoid hemorrhages (cSAHs) are relevant neuroimaging markers of CAA.¹

The exact nature of TFNE is not yet elucidated: an epileptic origin was suspected but never proved.^2,3 A correct pathogenic framing of these disturbances is needed to avoid treatments such as thrombolytic therapy or anticoagulation, which could be highly deleterious in CAA. In differential diagnosis, blood-sensitive MRI sequences are important to obtain because they may reveal signs of silent microbleeds and cortical superficial siderosis that allow a diagnosis of probable CAA.^4,5

Case

We report the case of an 87-year-old woman with a history of hypertension and a previous ischemic stroke that left her without relevant functional impairment or sensory complaints who presented to the emergency department referring the acute onset of hypesthesia and paresthesia involving her right arm and leg, lasting from the previous night (8 hours). Neurologic evaluation showed a minimal right pronator drift and a right static facial deficit, referred by the patient as residual from the previous stroke. CT showed diffuse white matter hypodensities, with a slightly left predominance (figure e-1A, links.lww.com/CPJ/A150). The CT angiography showed no large vessel occlusion or arterial vascular malformations (figure e-1B, links.lww.com/CPJ/A150). She did not receive IV recombinant tissue plasminogen activator due to late presentation and was not eligible for mechanical thrombectomy because of the absence of a large vessel occlusion. She was admitted to our stroke unit for clinical and instrumental monitoring.

During the first days of clinical observation, sensory complaints gradually improved until disappearance. Brain MRI performed 4 days after the onset of symptoms showed no diffusion-weighted imaging-restricted alterations and confirmed the presence of diffuse supratentorial white matter confluent hyperintensities (figure 1A). Signs of hemosiderin deposition along the left primary sensory cortex (consistent with a previous cSAH) together with the presence of numerous CMBs suggested a diagnosis of probable CAA according to the modified Boston criteria⁶ (figure 1B).

Figure 1. MRI During Sensitive Complaints.

(A) T2-weighted axial MRI showing the presence of diffuse supratentorial white matter confluent hyperintensities (no diffusion restricted lesions were detected on DWI/ADC scans). (B) On gradient-echo (GE) scans, a high number of CMBs were detected and an evident hemosiden deposition along left primary sensory cortex (suggestive for a previous cSAH) was shown.

EEG performed during the occurrence of sensory symptoms showed the presence of sharp, high-amplitude, irregular, arrhythmic theta-delta activity with left temporoparietal prevalence and a tendency to diffusion to the contralateral areas (figure 2A).

Figure 2. EEG Activity Evolution.

(A) EEG performed during sensitive complaints and showing left temporo-parietal slow activity with a sharp appearance (red oval) and tendency to ipsilateral (green oval) and contralateral diffusion (blue oval). (B) EEG performed three months after the introduction of lamotrigine, showing disappearence of epileptiform activity.

Lamotrigine (25 mg once a day) was started and gradually titrated as treatment for focal aware seizures with sensory symptoms (according to the International League Against Epilepsy operational classification of seizure types⁷), with no adverse events. On discharge, the patient had no sensory complaints. At the 3-month clinical reevaluation, the patient referred no sensory complaints. EEG showed regression of the epileptiform activity seen 3 months earlier (figure 2B). She was maintained on lamotrigine 50 mg twice a day.

Discussion

We described a patient with CAA with TFNE and epileptiform EEG activity. Previous reports only found intermittent focal slowing in similar cases.^2–5

In our patient, the registration of focal epileptiform activity during sensory complaints, the regression of EEG abnormalities after lamotrigine introduction, and the cessation of symptoms together with the absence of recurrence at follow-up suggest a possible role of cSAH-induced focal aware seizures as a clinical presentation of the CAA spectrum and underline the useful role of antiepileptic drugs in this often-recurring and disturbing manifestation.

Appendix. Authors

Study Funding

No targeted funding reported.

Disclosure

The authors report no disclosures relevant to the manuscript. Full disclosure form information provided by the authors is available with the full text of this article at Neurology.org/cp.