**3. Epidemiology**

Hitherto, publications concerning abdominal epilepsy are quite limited in number. Accurate prevalence rate of abdominal epilepsy has not been evaluated. There are 36 cases reported in literature, in the review of abdominal epilepsy by Zinkin and Peppercorn [4]. We found other 15 cases of abdominal epilepsy in


*Abbreviations: LOC, loss of consciousness; GTCS, generalized tonic-clonic seizure; NA, not available; CBZ, carbamazepine; PHE, phenytoin; LTG, lamotorigine; OXC, oxcarbazepine; DIA, diazepam; VPA, sodium valporate; CZP, clonazepam*

#### **Table 1.** *Summary of case reports by literature.*

In the widely accepted operational definition of epilepsy, it requires that an individual has at least two provoked seizures on separate days, generally 24 hours apart. There are various seizure types in accord with the cortical function of the epileptic foci and propagated areas in epilepsy. Abnormal abdominal sensation often heralds the onset of epileptic seizures. Among them, there is a rare syndrome called abdominal epilepsy in which episodic gastrointestinal complaints like abdominal pain, abdominal discomfort, nausea, vomit, and diarrhea are the primary or the sole manifestation of epileptic seizures. It is important for clinicians to know that abdominal epilepsy is one of the differential diagnoses of gastrointestinal signs, especially when they are acute onset and recurrent, and that it is treatable with

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Simplified diagram of central autonomic network (CAN)

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Here we review abdominal epilepsy as one of the causes in acute diarrhea.

Abdominal epilepsy is characterized by paroxysmal gastrointestinal signs and symptoms resulting from epileptic activity of the neurons in the brain. Epileptic seizures of several patients with abdominal epilepsy are accompanied with impairment of the CNS like loss of consciousness and headache. There is no authorized diagnosis criterion for abdominal epilepsy at present. Zinkin and Peppercorn propose the following criteria for diagnosis of abdominal epilepsy. That is to say, (1) paroxysmal gastrointestinal manifestations of undetermined origin after thorough evaluation including laboratory, radiographic, and endoscopy testing, (2) symptoms originated from the CNS, (3) an abnormal electroencephalogram (EEG)

antiepileptic medications.

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*Perspective of Recent Advances in Acute Diarrhea*

*Simplified diagram of central autonomic network (CAN).*

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**Amygdala**

**2. Definition**

**88**

**Figure 1.**

English literature after Zinkin's review paper [6–16]. In the reported cases, there is no racial specificity nor regional specificity. The number of patients with abdominal epilepsy could be more than reported cases because the entity of abdominal epilepsy has still not been recognized and because nonmotor seizure manifestations are often underdiagnosed. **Table 1** shows the patient profile of 15 case reports that was published after his review. Elderly patients of more than 60 years old are only 1 case (2%) out of his 36 cases and 4 cases (26%) out of 15 cases. Recently there is increasing evidence that elderly with dementia have greater risk of epilepsy. Hayashida et al. reported that the cumulative incidence of at least one unprovoked seizure in individuals with Alzheimer's disease is in the range of 10–20% [14]. From now on, the number of abdominal epilepsy could be increased along with the increase of elderly patients with epilepsy.

significant epileptiform discharges are detected. Spikes and sharp waves are epileptiform discharges that reflect the paroxysmal depolarization shifts in the epileptic neurons. They are basically surface negative but in rare occasions surface positive. Patients with epilepsy has abnormal EEG findings even though they are in interictal state. Interictal epileptic discharge like spikes and sharp waves is recognized on EEG of abdominal epilepsy patients; however, less specific EEG changes can be a clue for

*Acute Diarrhea as a Manifestation of Abdominal Epilepsy*

*DOI: http://dx.doi.org/10.5772/intechopen.86719*

In patients with epilepsy, generally speaking, the initial EEG examination shows interictal epileptiform discharges in only about 50%; therefore, normal EEG does not exclude the presence of epileptic disorder. It is hard to capture the abnormal signals in case of deeper lesion and/or small foci in the brain. As for enhancement of sensitivity, the detection rate is increased by performing repeated EEG at different times or by physiological activation procedures like hyperventilation, sleep recording, and photic stimulation. Long-term video EEG monitoring is one of the useful tools for diagnosis of epilepsy. Video EEG monitoring is an EEG record with video recording continuously for several days including sleep in the night and performed for direct correlation of clinical symptoms with EEG findings. When the gastrointestinal signs and symptoms occur and abnormal EEG findings (epileptiform discharge) are recognized at the same time, the diagnosis of epilepsy is determined. In most of the reports in the past, abnormal findings on EEG are interictal, but only one case report has ictal EEG recording showing left anterior temporal onset [16].

Seizure semiology of abdominal epilepsy is usually categorized as partial seizures (simple partial seizures with preserved consciousness, complex partial seizures with impaired consciousness, and secondarily generalized seizures with loss of consciousness and generalized convulsion) [4]. Based on the operational classification of seizure types by the International League Against Epilepsy (ILAE) (2017), epileptic seizures with onset of autonomic features are classified into autonomic (onset) seizures. According to the "ILAE classification of the epilepsies: Position paper of the ILAE Commission for Classification and Terminology," [18] abdominal

In history, many cases have been described, and many terms have been used for paroxysmal autonomic symptoms including gastrointestinal ones classified as epilepsy from the times of Armand Trousseau [19]. Moore used the term abdominal epilepsy for the first time for patients with abdominal pain or abdominal pain with nausea and vomit caused by epileptic seizures [20]. Because sensory symptoms are related to loss of consciousness or any other impairment of central nervous system,

The mechanism that abdominal epilepsy occurs is still unclear, but several studies indicate that temporal lobe structures including the amygdala and hippocampus, insular cortex, and limbic systems could be related with inducing abdominal sign and symptoms known as abdominal epilepsy [4]. Ictal autonomic changes are probably due to direct excitation or inhibition of neocortex and limbic systems involved in seizure onset and their propagation to structures that constitute the central autonomic network (**Figure 1**) [21]. The brain controls widespread autonomic responses through the central autonomic network ranging from the cerebral hemisphere to the brain stem. The insular and medial prefrontal cortices, the hippocampus, and the amygdala are the major inputs to transmit cortical activity to the central nervous network. Certain autonomic symptoms and signs (vomiting, nausea, and alterations in heart rate and respiration, flushing,

epilepsy is categorized as a focal epilepsy, whatever the etiology may be.

the sensory symptoms are regarded as an aura [21].

diagnosis.

**6. Pathophysiology**

**91**

## **4. Clinical features**

Abdominal epilepsy is quite uncommon. Zinkin and Peppercorn found only 36 reported cases in the English literature since Douglas and White laid the groundwork in the reporting of cases of abdominal epilepsy in 1971, and they reviewed 36 patients with abdominal epilepsy in the past 34 years [4]. After their report, we found other 15 adult cases in English literature (**Table 1**). Age of patients varies a great deal from 1 to 71 years, and female is 57% (29/51), without any significant predisposition. Gastrointestinal manifestations of epilepsy include abdominal pain in 76% (39/51), nausea and/or vomit in 43% (22/51), and diarrhea in 6% (3/51); in abdominal epilepsy, rate of occurrence of diarrhea is quite rare as a gastrointestinal symptom. All three patients with diarrhea had the abnormal findings on EEG in temporal area. Antiepileptic drugs were prescribed (phenobarbital, valproic acid, and carbamazepine). The outcome was complete resolution or well-controlled.

#### **5. Examination**

General physical examination is unremarkable. The examination directly related with gastrointestinal signs and symptoms, for example, abdominal computed tomography (CT) scan, abdominal ultrasound, and gastrointestinal endoscopy, is normal. Blood tests and cerebrospinal fluid examination are usually normal.

Neuroimaging like magnetic resonance (MR) imaging and/or CT scan or singlephoton emission computed tomography (SPECT) sometimes shows local lesion, especially in temporal areas. Two cases have no remarkable MR imaging and/or CT but abnormal findings in temporal lobe or areas including temporal lobe on brain SPECT (one, decreased blood flow in the left frontal and temporal; the other, perfusion defects in the frontotemporal-parietal area) [12, 14]. There is one patient who has abnormal lesion in temporal lobe on MR imaging (left mesial temporal sclerosis) [16]. No specific finding is relevant to diagnosis of abdominal epilepsy.

As is the case with any type of epilepsy, EEG is one of the most important examinations for abdominal epilepsy. EEG is a record of the electrical potentials generated in neurons from electrodes attached to the human scalp. One estimate is that approximately 6 cm<sup>2</sup> of cortical surface must be synchronously activated in order for there to be a potential recorded at the surface [17]. Abnormal EEG activity can be classified into two types: epileptiform and non-epileptiform. The two most important types of abnormal activity are slowing and epileptiform activity. Slow waves indicate disordered function of the neuron, whereas epileptiform activities indicate abnormal synchronous activity [17]. EEG is of diagnostic power when

#### *Acute Diarrhea as a Manifestation of Abdominal Epilepsy DOI: http://dx.doi.org/10.5772/intechopen.86719*

significant epileptiform discharges are detected. Spikes and sharp waves are epileptiform discharges that reflect the paroxysmal depolarization shifts in the epileptic neurons. They are basically surface negative but in rare occasions surface positive. Patients with epilepsy has abnormal EEG findings even though they are in interictal state. Interictal epileptic discharge like spikes and sharp waves is recognized on EEG of abdominal epilepsy patients; however, less specific EEG changes can be a clue for diagnosis.

In patients with epilepsy, generally speaking, the initial EEG examination shows interictal epileptiform discharges in only about 50%; therefore, normal EEG does not exclude the presence of epileptic disorder. It is hard to capture the abnormal signals in case of deeper lesion and/or small foci in the brain. As for enhancement of sensitivity, the detection rate is increased by performing repeated EEG at different times or by physiological activation procedures like hyperventilation, sleep recording, and photic stimulation. Long-term video EEG monitoring is one of the useful tools for diagnosis of epilepsy. Video EEG monitoring is an EEG record with video recording continuously for several days including sleep in the night and performed for direct correlation of clinical symptoms with EEG findings. When the gastrointestinal signs and symptoms occur and abnormal EEG findings (epileptiform discharge) are recognized at the same time, the diagnosis of epilepsy is determined. In most of the reports in the past, abnormal findings on EEG are interictal, but only one case report has ictal EEG recording showing left anterior temporal onset [16].
