Article, Neurology

Diagnosing frontal lobe epilepsy in the ED

Case Report

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American Journal of Emergency Medicine

journal homepage: locate/ ajem

Diagnosing frontal lobe epilepsy in the ED

Abstract

Frontal lobe seizures are a common form of epilepsy. It has a variable presentation and can often be missed in the emergency department (ED). Missing this diagnosis can lead to a delay in treatment and poor outcome for cognitive function. We hereby present a case of a 14-year-old girl who presented to our ED after the development of abnormal movements. Knowledge of the anatomy behind the development of partial seizures and the best testing modality can aid in the diagnosis. In this review, we attempt to discuss the pathophysiology of frontal lobe epilepsy and what physical examination findings and testing will best lead to a diagnosis.

Seizures account for 1% of emergency department (ED) visits, with higher proportions in the pediatric ED [1]. Temporal lobe epilepsy is the most common form. Frontal lobe epilepsy is the second most common afflicting up to 30% of partial epilepsies [2,3]. The etiology of frontal lobe seizures is not entirely clear. Some causes include trauma, tumors, vascular malformations, encephalitis, cortical dysplasia, and idiopathic syndromes [3]. Untreated seizures can cause problems with existing cognitive function including linguistic performance, memory, behavior, and motor coordination [3].

The frontal lobe itself plays an important role in motor function, executive function, eye movements and speech, and linguistic abilities [4]. Frontal lobe epilepsy has a variable presentation [5]. Seizures are generally brief, stereotypic, nocturnal, and frequent [6]. When it affects the motor cortex, it typically shows contralateral clonic movement as well as complex automatism [7]. This diagnosis is frequently missed and often gets classified as psychiatric in origin given a variety of presentations and bizarre behavior.

A 14-year old girl presented to the ED with a chief complaint of “twitching” in her right eye and right hand. She reports having intermittent episodes of these movements for the last 2 days, but on the day of presentation, the movements have been sustained. She presented with rhythmic clonic movements in her right eyebrow and right index finger. She was unable to suppress the movement. Otherwise, her physical examination was normal. Initial electroen- cephalogram (EEG) was not suggestive of seizures. Magnetic resonance imaging (MRI) with contrast revealed a focus of cortical restricted diffusion in the high left central sulcus. She was admitted to the hospital. Stroke workup with echocardiogram, magnetic reso- nance angiography head and neck, and magnetic resonance venog- raphy were negative. The abnormality seen on MRI was thought to be related to focal status epilepticus (see Fig. 1). After a 10-day inpatient stay and multiple antiepileptic regimes, her seizures ceased, and she was discharged home.

Frontal lobe epilepsy is second next to temporal lobe epilepsy in prevalence. Other forms of neocortical epilepsy are less common. Occipital lobe epilepsy tends to present with Visual disturbances, whereas parietal lobe epilepsy lacks a distinguishing clinical syn- drome but can have localizing somatosensory symptoms. [8,9] Crucially, with such a variable presentation, neocortical epilepsy can be misdiagnosed for psychogenic nonEpileptic seizures, sleep distur- bances, or motor tics.

One of the challenges in diagnosing frontal lobe epilepsy is that it may not reveal itself on EEG. [3,5,7] Magnetic resonance imaging can be a useful diagnostic tool. Most patients will have a normal MRI, but it is one of the more sensitive modalities for diagnosing frontal lobe epilepsy [10]. In addition, it is the only diagnostic tool that has been shown to predict surgical outcome [10]. However, one must have a high suspicion based on the physical examination before pursing further workup.

Knowledge of the homunculus can help clue providers that patients presenting with “tics” may actually be having partial seizures, particularly those affecting the primary motor cortex. The motor homunculus is a distorted model of the human body to represent the

Fig. 1. Magnetic resonance imaging demonstrates a small area of restricted diffusion in the left frontal lobe, which appears to be in the primary motor cortex.

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drug-resistant frontal lobe epilepsy as she had been tried on more than 2 types of antiepileptic drug schedules. However, she was eventually able to become seizure free with optimal drug therapy.

In our patient, frontal lobe epilepsy was strongly suspected based on her clinical presentation. Knowledge of the manifestations of neocortical seizures can help aid in diagnostic workup and appropri- ate evaluation by neurology consultants. Missing such a diagnosis can lead to delays in treatment and existing cognitive performance. This can have a significant impact on the patient’s social interactions, scholastic activity, and overall quality of life.

Appendix. Supplementary data

Supplementary data to this article can be found online at http://dx. doi.org/10.1016/j.ajem.2014.03.025.

Lara Phillips, MD Michele Walsh, MD

Vanderbilt University Medical Center, Nashville, TN E-mail address: [email protected]

http://dx.doi.org/10.1016/j.ajem.2014.03.025

Fig. 2. The motor homunculus is a distortED representation of the human body parts, which correlate to the areas of the primary motor cortex, which controls them.

relative space each body part controls along the motor cortex (see Fig. 2). For example, areas with fine motor movements such as the hands and face have more neurons dedicated to them as compared with the parts of the brain that correspond to areas such as the torso, which do not control as precise movements. Partial seizures involving the primary motor cortex, like our patient, will produce contralateral hemiclonic activity [7]. This may help lead providers to pursue a further workup. The diffusion abnormality on the MRI in this case demonstrated a small area of restricted diffusion in left frontal lobe. This was anatomically consistent with her symptoms on the right side mapped out onto the left brow and finger on the homunculus primary motor cortex.

Frontal lobe epilepsy is unfortunately complicated by pharmaco- therapy resistance and may require epilepsy surgery [3]. Some studies suggest that poor seizure control can lead to developmental regression, although this is controversial [3]. Our case exhibited a patient who had

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