As far as we know, there were no major hospital-based studies which evaluated new-onset seizures in adults especially from Egypt.
Most epidemiologic studies of seizure disorders are studies of the prevalence of epilepsy and only a few prospective incidence studies of cases with a first seizure in the adult population exist [8].
The importance of adult-onset seizures stems from their frequent association with secondary causes. If proper analysis of etiology is made with history taking, clinical examination, and appropriate investigations, the presenting seizures can be treated accordingly, thus reducing associated morbidity and mortality [2].
In 2010, the International League against Epilepsy (ILAE) Commission for Classification of Epilepsy divided epilepsies into three main categories (idiopathic mainly “genetic”, structural or/metabolic, unknown cause “cryptogenic”) according to the etiologies of epilepsy [9].
In the present study, we evaluated the data of 120 patients presented to ER and Neurology Clinics, who aged (≥ 18 years old) at the time of first seizure. Males represented (63.33%) of our cohort, while females represented (36.67%) with male to female ratio (1.7:1).
Our results are in concomitant with two studies reporting M:F ratio 1.85:1 and 1.9:1, respictively [2, 8].
Another study group reported that the rate of new-onset seizures was considerably higher in men than in women. The same study group reported that acute symptomatic seizure is also common in older patients. The incidence of acute seizures in patients over age 60 was estimated at 50 to 100 per 100,000 per year [10].
In the current study, we reported that new-onset seizures (NOS) were more common in the older age group (> 55 years), accounting for 60% of total cases.
Another community-based epidemiological study showed that the average annual incidence of epilepsy in the elderly aged 65 years and older is up to 240 per 100,000 [11].
In concomitant to our study, a study group reported that the number of patients with first seizure is more in the age group > 60 years [12].
It is in contrary to other studies done in India, where the majority of cases were the young and middle-aged groups < 40 years, with a higher prevalence of CNS infections in these age groups provoking symptomatic NOS [2, 8, 13].
Past medical illnesses usually give a clue to the possible etiology. History of hypertension was significantly associated with unprovoked seizures, whether associated or not with stroke [14].
In the current study, 61 patients (50.83%) had PH of systemic HTN and 42 patients had PH of CVA (35%).
Subjects with a history of both had a fourfold increase in seizure risk compared with subjects with neither, probably due to the synergism between PH of CVA and PH of HTN [14].
Another study group found that hypertension was present in 16% of their cohort with NOS and PH of CVA among 8% [12].
Alterations of metabolic homeostasis are associated with seizures in many situations and may be the only symptom of electrolyte imbalances. These are commonly seen in people with hyponatremia, hypocalcemia, hypoglycemia, and hyperglycemia. The more rapid the disturbance develops the more likely it is to induce seizures [15, 16].
In the present study, 10 patients had acute symptomatic metabolic seizures. Five patients were diagnosed with hypocalcemia-induced NOS, 3 patients had NOS out of hyperglycemia, 1 patient had NOS secondary to uremia, and 1 patient had hyponatremia-induced NOS.
Regarding neuroimaging investigations, in patients in whom lesions could not be picked up by CT brain in spite of clinical evidence of structural lesion, MRI brain (with or/without contrast) was done.
Two studies revealed that CT failed to detect the abnormality in MRI-positive cases 26% and 57% of the time [17].
In the current study, neuroimaging abnormal findings were detected among (75%) of the participants. A recent study recruited 416 adult patients with NOS, detected neuroimaging abnormalities among 53% of its cohort [17].
Ischemic infarctions were the most common brain scan finding among our cohort (41.76%), followed by SOLs (10%).
These findings are in concomitant to other studies which recruited 100 cases presented with adult new-onset seizures. The most common abnormal CT findings were ischemic infarcts (18%), followed by brain tumors (either primary or secondary) (8%) [2].
However, different study results were influenced by endemic infectious diseases. One group study concluded that the most common abnormality in CT scan was a ring-enhancing lesion (mostly tuberculoma) (12%) as well as cerebral infarcts (12%), followed by generalized cerebral atrophy (4%) and meningioma, gliosis, and calcification (2%) for each [13].
The above findings highlighted the importance of neuroimaging among adult-onset seizures patients for appropriate etiological diagnosis of seizures.
Electrophysiological data were useful; it detected abnormality among 37.5% of our cohort. EEG epileptiform activity (spikes and sharp waves) was detected in 19.1% of the patients, while non-epileptiform activity (cerebral slowing) was detected in 18.3%.
In the current study, out of 30 patients with normal neuroimaging studies, 24 patients underwent DEEG study; of those, 15 patients had abnormal DEEG findings, revealing the yield of post-ictal DEEG in NOS.
Our results were in concomitant with other studies. One study reported that out of 100 patients with new-onset seizures, 44% had abnormal DEEG records suggestive of seizure activity where as the remaining 56% had normal DEEG records [2].
The same results were reported in another study with DEEG abnormalities among 40% of their patient and normal DEEG among 20% [12].
In contrast to another group who studied NOS among the older age cohort only (> 65 years old), they reported abnormal EEG in 18.8% of their cohort and normal EEG in (49.3%) [18].
Younger patients with epilepsy often show a genetic cause. However, new-onset epilepsy in the elderly is mainly the consequence of accumulated injuries to the brain and other secondary factors [19].
New-onset epilepsy in elderly people often has underlying etiology including cerebrovascular diseases, brain tumors, and traumatic head injury. Post-stroke seizure is likely to increase because of the increasing aging population, and age itself is an independent risk factor for stroke [20].
The present study revealed that CVDs are the most common etiology for adult new-onset seizures by post-stroke seizure/epilepsy (44.17%). CVDs had the highest prevalence in the older adult (> 55 years) age group (65.28%).
Therefore, a close follow-up of stroke patients is needed for early detection of subtle fits which are hardly identified by the patients themselves or their caregivers, as well as understanding the characteristics of post-stroke seizures, etiological causes, and drug-drug interactions while treating those patients is necessary for effective patient management.
The second most common identified etiology for adult new-onset seizures was idiopathic epilepsy syndrome (18.33%), followed by SOLs (brain tumors) (9.17%), acute symptomatic metabolic seizures (8.33%), post-traumatic epilepsy (6.67%), encephalitis (5.83%), and cryptogenic (5%).
Among identified etiologies of new-onset seizures in relation to age, idiopathic seizures were more common in younger adults (55.56%) followed by cryptogenic (14.8%) and post-traumatic epilepsy (11%) with P value (< 0.001).
Encephalitis-related seizures were common in the older age group (6.94%) in comparison to young adults (3.7%) and middle-aged adults (4.7%); post-traumatic seizures were more common among middle-aged (14.29%) and young adult (11.11%) groups in comparison to older age group (2.78%).
The mentioned results were in concomitant with other study groups’ results. One study found that stroke was the most common etiology of adult new-onset seizures (23%), followed by idiopathic (22%) [2].
Another group studied 50 cases of adult new-onset seizures and found that CVDs were the most common etiology (34%) followed by idiopathic (22%) being the second most common etiology [12].
The same results were revealed by a study group that recruited 100 cases presented with new-onset seizures in adults and found that stroke was the leading cause of seizures accounting for 21%; infection was the next leading cause of seizures accounting for 17% and metabolic causes account for 15% [1].
However, endemic CNS infections in some areas dramatically changed the results of a study done in India, which enrolled 98 cases presented with new-onset seizures after age 20 years. They reported that CNS infections mainly “neurocystecercosis” were the leading cause of first seizure in adults accounting for 39.7%, followed by CVDs (26.5%) [8].
The present study revealed that CVDs were the most prevalent etiology of new-onset seizures among males (43.4%), as well as females (45.4%). However, male predominance was the highest among post-traumatic epilepsy (87.5%), while female predominance was the highest among brain tumors identified etiology of new-onset seizures (54.5%).
The different heterogeneity of etiologies, i.e. CVDs, idiopathic, post-traumatic, SOLs, metabolic, and CNS infections among adult patients with new-onset seizures and their relative contributions, depend on the age composition of the study population, sample size, and endemicity of CNS infections.
One of our study limitations is the narrow window for post ictal EEG 48–72 h that resulted into 34% dropping and missing of this pivotal investigation in our epileptic patients. Future research direction for recruitment of more patients through multicenter contribution can aid in making a national registry system and database for NOS patients across the country.