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Year : 2015  |  Volume : 42  |  Issue : 2  |  Page : 82-87

New onset seizures: Etiology and co-relation of clinical features with computerized tomography and electroencephalography

Department of General Medicine, Vijayanagara Institute of Medical Sciences, Bellary, Karnataka, India

Date of Web Publication14-May-2015

Correspondence Address:
V Muralidhar
Department of General Medicine, Vijayanagara Institute of Medical Sciences, Bellary, Karnataka - 583 104
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0974-5009.157036

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Aims and Objective: To establish whether the reported episode was a seizure, to determine the cause of seizure by identifying the risk factors, lab, radiological and electroencephalography (EEG) evaluation to determine any underlying structural abnormality and to decide whether anti-epileptics therapy is essential. Settings and Design: This was a descriptive study. Materials and Methods: (1) Source of data - All the patients with inclusion criteria attending to the medicine outpatient department (OPD)/wards. Sample size = 50 cases. (2) Study subjects - Inclusion criteria: All patients >15 years age group presenting in medicine OPD/wards with the first episode of seizure. Exclusion criteria: Seizures on treatment and head injury. Methods of Collection of Data: Each patient was subjected to the detailed evaluation including history, precipitating factors, and symptomatology recorded accordingly. History of hypertension, diabetes mellitus, tuberculosis (TB) was enquired into. Family history of epilepsy, TB was recorded. Complete clinical evaluation and thorough investigations-complete blood count, urine examination, blood urea nitrogen, random blood sugar, chest X-ray, computerized tomography (CT) scan and EEG were done for all patients in the inclusion criteria. Anti-epileptics were started if either CT/EEG was abnormal, rest of the patients were not given anti-epileptics. Follow-up was done for 6 months, and any recurrence of seizures was noted. The data collected from cases in the inclusion criteria were recorded in a Master chart. Data analysis was done using appropriate statistical tests and graphs. Results and Conclusions: Peak incidence of new onset seizure was second to third decade (25 cases; 50%), max cases <25 years, male: Female ratio of 2.12:1, duration of seizure <5 min (30 cases; 60%), evidence of TB = 6 cases (12%), alcohol intake = 5 cases (10%), developmental delay = 3 cases (6%), family history = 3 cases (6%), old cerebro-vascular accident = 2 cases (4%), neurological abnormalities (CT scan) =11 cases (22%), EEG abnormalities = 4 cases (8%), recurrence = 12 untreated cases (24%).

Keywords: Anti-epileptics, computerized tomography scan, electroencephalography findings, risk factors, seizure

How to cite this article:
Muralidhar V, Venugopal K. New onset seizures: Etiology and co-relation of clinical features with computerized tomography and electroencephalography. J Sci Soc 2015;42:82-7

How to cite this URL:
Muralidhar V, Venugopal K. New onset seizures: Etiology and co-relation of clinical features with computerized tomography and electroencephalography. J Sci Soc [serial online] 2015 [cited 2021 Jul 26];42:82-7. Available from: https://www.jscisociety.com/text.asp?2015/42/2/82/157036

  Introduction Top

Seizure is defined as paroxysmal clinical event due to abnormal excessive hypersynchronous discharges from an aggregate of central nervous system neurons. Although a variety of factors influences the incidence and prevalence of seizure, approximately 5-10% of the population will have at least one seizure during their lifetime.

Although the cause of seizure varies of age, the onset of most of the seizures is in childhood or adulthood. Many causes are a common result of endogenous factors, epileptogenic factors, and precipitating factors. Precipitants include those due to intrinsic physiologic processes such as psychological or physical stress; sleep deprivation or hormonal changes associated with the menstrual cycle as well as exogenous factors such as exposure to the toxic substance and certain medications.

Clinical evaluation includes emphasis to:

  1. Establish whether the reported episode was a seizure rather than another paroxysmal event.
  2. Determine the cause of the seizure by identifying risk factors and precipitating factors.
  3. Lab radiological and electro graphical evaluation to determine whether there is an underlying structural abnormality that is responsible.
  4. Decide whether anti-epileptics therapy is required in addition to treatment for any underlying illness. When patient is presented with 1 st episode of seizure, it is controversial to start anti-epileptics drug therapy.
Generally accepted risk factors associated with recurrent seizure include the following:

  1. Abnormal neurologic examination.
  2. Seizure presenting as status epileptics.
  3. Postictal Todd's paralysis.
  4. Strong family history of seizure.
  5. Computerized tomography (CT) and abnormal electroencephalography (EEG).
Many patients present to the emergency department with the first episode of doubtful seizure. Starting anti-epileptics in this patient is controversial and not clearly understood. So, this study aim at studying all these aspects of seizure that is, clinical evaluation, CT, and EEG correlation and follow-up for 6 months in cases who do not have any CT or EEG abnormality.

  Materials and methods Top

Selection of cases

The present study has been done in our tertiary care hospital in Department of Medicine, during the period December 2010-September 2012.

A total number of 50 cases, presented with new onset seizure was included in the study and was evaluated with the help of clinical history, examination, CT scan (head) and EEG. Cases were selected by random sampling method.

Inclusion criteria

All patients above 15 years age group presenting in Vijayanagara Institute of Medical Sciences (VIMS) Hospital with the first episode of seizure.

Exclusion criteria

  1. Patients with seizures on treatment.
  2. Patients with head injuries.
Study design

This study is a descriptive study. The included cases were taken either from the hospital wards or those attending the medicine outpatient department (OPD) after satisfying the criteria.

Plan of study

In each patient, a detailed evaluation including history, the type, duration, precipitating factors and associated symptoms were taken along with other symptomatology.

Anti-epileptics treatment was started if either CT/EEG was abnormal. Rest of the patients were not given anti-epileptic treatment. Follow-up was done for 6 months, and any recurrence of seizure was noted. History of hypertension, diabetes mellitus, pulmonary tuberculosis (TB), head injury, contact with TB and dietary history was enquired into.

After a complete clinical examination, all cases had undergone investigations like complete hemogram, erythrocyte sedimentation rate, urine examination, blood sugar, blood urea, serum creatinine, chest radiograph posteroanterior view along with CT scan of the head and EEG.

Data obtained from these patients were systematically recorded and analyzed using Statistical Package for Social Services version 15.0 (IBM SPSS inc., Chicago, IL), Chi-square was used to assess statistical significance. A P < 0.05 was considered as statistically significant.

  Results Top

A total number of 50 cases either from hospital ward or patients attending medicine OPD, VIMS Combined Hospital, Bellary, was taken who presented with a history of new onset seizure. All cases were evaluated with the help of clinical history, detailed physical examination and investigation including CT head and EEG.

Majority of cases were in age group 16-25 years (n = 25, 50%). The youngest patient was of 16 years and the oldest patient was 80 years old [Graph 1].

Mean age = 33.14, standard deviation of 32.94 ± 15.89 [Table 1].
Table 1: Age distribution of cases of new onset seizure

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Out of 50 cases, 34 cases (68%) were males, and 16 (32%) were females. Male to female ratio was 2.12:1.

Study regarding duration of new onset seizure showed that out of 50 cases, 30 cases (60%) had seizure for <5 min, 15 cases (30%) had seizure for 6-10 min, 5 cases (10%) had seizure for >10 min. Mean duration of seizure was 5.44 min. Standard deviation of 5.44 ± 2.90.

Out of 50 cases of new onset, seizure history/evidence of TB (pulmonary/extra-pulmonary) was present in 6 cases (12%). Five cases (10%) was alcoholic, 3 (6%) has a history of developmental delay in the past. Three cases (6%) had family history of seizure in sibling/first-degree relatives, 2 cases (4%) had a history of cerebro-vascular accident (CVA) in the past [Graph 2].

Neurological signs in the new onset seizures are seen in 24% patients [Graph 3].

Computerized tomography scan head was done in all the 50 cases, and contrast was given when required; out of 50 cases, 33 cases (66%) had normal CT scan head. CT abnormalities are given in [Table 2].
Table 2: CT scan abnormalities in cases of new onset seizure

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Electroencephalography was done in all 50 cases. Abnormal EEG was seen in 4 cases (8%), out of which 3 cases (6%) showed features of single temporal interictal epileptiform discharge (IED) discharges and 1 case (2%) showed focal abnormality. CT was abnormal in 3 cases with single temporal IED discharges in EEG out of 3 cases. One case with abnormal EEG showing focal discharge was associated with normal CT head study.

All Cases with abnormal CT/EEG were given anti-epileptic treatment. Rest of the cases (31 cases) were followed without anti-epileptic treatment for 6 months, and any recurrence was noted.

Out of 31 untreated cases, 6 (19.3%) had recurrence in next 6 months. Two cases in 16-25 age group (16.7%), 2 cases in 26-35 age group (16.7%), 1 case in 36-45 age group (3.3%), 0 case in 46-55 age group and 1 case in >55 age group (3.3%) had recurrence. Out of the total number of 6 recurrences, 3 (50%) occurred within 14 days of first seizure, 2 (33.3%) occurred within 21 days, and 1 case occurred within 7 days.

Cases in recurrence and nonrecurrence group were compared [Table 3].
Table 3: Comparison of cases of recurrence and nonrecurrence

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  Discussion Top

The accumulated data from clinical evaluation, biochemical test, EEG and imaging have been analyzed and compared with other studies. Similarities and differences have been noted which will help in drawing conclusion from this study.

In the present study, total number of 50 cases from the ward and OPD of medicine, VIMS Combined Hospital, Bellary, with a history of new onset seizure was included after satisfying the criteria.

Patients <25 years constituted 25 cases (50%) as compared to 48% in a study by Musicco et al. [1] Mean age at the time of seizure was 33.14 years in the present study. It was 24.8 years in study of Mussico et al. [1] and 32 years in study of van Donselaar et al. [2] In study of patients 20 years or more, the most frequently affected age group is up to 30 years. This is similar to result of Hopkins et al. [3] in which most frequently affected age range was 16-29 years.

Male to female ratio is 2.12:1 in the present study. Most authors report a mild to moderate preponderance of males in their studies van Donselaar et al., [2] Mussico et al., [1] Hopkins et al. [3]

Annegers et al. [4] and Bora et al. [5] found a slight preponderance of female cases in their study.

In our study, mean duration of seizure was 8.35 min as compared to 6.23 min in a study by Bernal and Altman. [6] Maximum patient (30 cases; 60%) had seizure duration <5 min that is similar to the study done by Benbadis et al. [7]

Among the various risk factors studied, positive history/evidence of TB was found in 6 cases (12%). Bhatia and Tadon [8] found it in 8% of cases and Shinnar et al. [9] found it in 10% cases. Five cases (10%) had a history of alcoholism. History of significant head injury is known to be a risk factor for the occurrence of seizure in later age group (Nowack and Anthony). [10]

History of developmental delay was present in 3 cases (6%), 2 of them were male and 1 was female. Annegers et al. [4] and Bora et al. [5] have shown that neurologic deficit from birth was more common in association with seizure in males as compared to females in their studies. History of old CVA was present in 2 cases (4%). Roberts et al. got CT evidence of vascular pathology in 11% of his cases. Family history was present in 3 cases (6%) in our study while Shinnar et al. [9] found positive family history in 5% of cases that is almost similar to our study.

Various neurologic signs were present in 11 cases (22%). In a study by Bogdanoff et al. [11] neurologic examination was abnormal in 26% cases while it was 20% in the study of Loiseau et al. [12] Papilledema was present in 2 cases (4%). Focal motor deficit was present in 8 cases (16%). Shinnar et al. [9] found motor deficit in 10% of cases. In present study, 3 cases (6%) presented with altered sensorium in the postictal state. In CAROLE study done in 2001 shows number of patient presented with altered sensorium was 12.5%.

Computerized tomography scan head was done in all 50 cases. It was abnormal in 17 cases (34%) and normal in 33 cases of (66%). In a study by Wallace, [13] CT revealed lesion in 51 out of 132 patients (38%) of a single seizure. Scollo-Lavizzari et al. [14] showed that CT was diagnostic in 34% case of generalized seizure. Bernal and Altman [6] found 37% CT head abnormality in patients presented with a single seizure. But reports in various study varies from 19% Young et al. [15] to 51% Rogel-Ortiz. [16]

Most common abnormality in CT scan was ring enhancing lesion which was seen in 6 cases (12%). Others were the infarct in 6 cases (12%), generalized cerebral atrophy in 2 cases (4%), meningioma, gliosis and calcification each in 1 case (2%). This is comparable to study by Rogel-Ortiz [16] in which also the most frequent cause was ring enhancing lesion (28%) followed by CVAs including both infarction and hematoma and brain atrophy (11%). Ring enhancing lesion in the study of Rogel-Ortiz [16] was neurocysticercosis (NCC).

One study by Bhargava and Tandon [17] shows most common cause of single small CT enhancing lesion was tuberculoma. Study conducted by Chandy et al. [18] shows NCC was the most common cause of single small CT enhancing lesion.

Electroencephalography abnormality was present in 4 out of 50 cases (8%) in our study. According to van Donselaar et al., [2] standard EEG detects epileptiform discharges in 29% of patients. A Hirtz et al. [19] found abnormal EEG in 42% of cases of singles seizure during the postictal period in their study.

In our study, anti-epileptic treatment was given to all patients with abnormal CT scan head or EEG. Rest of the patients were not given any anti-epileptic treatment (31 cases; 62%) and were followed for next 6 months. Any recurrences in them were noted. Total of 6 cases (24%) recurred. In previous studies, the recurrence rate has varied from 26% to 71% Treiman, [20] but the duration of follow-up varied. In a study by Scotoni et al., [21] 6 months follow-up showed 18% recurrence rate, which is comparable to our study. Chadwick and Smith [22] also found 21% recurrence rate in 1 year follow-up but most of the recurrences in his study was within 3 months that is comparable to our study.

Out of 6 cases, 2 (33%) cases, 2 case each were in 16-25 years and 26-35 age group, >55 years had no recurrence, 2 cases were in 46-55 age group. This is similar to study by Mussico et al. [1] in which age group <16 years had almost double the risk of recurrent seizure compared to the age group 16-60 years.

Sex difference in recurrence and nonrecurrence group was not significant. Three out of 13 (23.1%) cases in male and 3 out of 12 (25%) in female group recurred, which is similar to study by Chadwick and Smith. [22]

Mean duration of seizure in the recurrence group was 34 min compared with 6 min in nonrecurrence group. One of the patients had presented with status epilepticus. In a study by Das et al., [23] duration of seizure at initial presentation was 10.1 + 5.2 min in the recurrence group and 6.5 + 4.1 min in the nonrecurrence group. Mean duration of seizure was 26.4 min in the recurrence group and 4.6 min nonrecurrence group in a study conducted by Martinoviζ and Joviζ.[24]

Family history was present in 1 of 6 patients (16.6%) in the recurrence group but was present in 2 of 19 cases (10.5%) in nonrecurrence group whereas study by Das et al. [23] have reported sibling affected with epilepsy is a risk factor for seizure recurrence in a patient with a single seizure.

Fifty percentage of cases had abnormal neurological findings in the recurrence group as compared to 21% in nonrecurrence group, a result similar to Hauser et al. [25] who found it in 42% of cases. History of alcohol intake was present in 16.6% cases in the recurrence group as compared to 10.5% in nonrecurrence group in our study that is same as those of alcohol and epilepsy study group. Earnest et al. [26] also found the history of alcoholism in 12% of recurrent cases after single seizure.

History of neurological deficit from birth was present in 2 out of 6 cases (33%) in the recurrence group while none of the 19 cases (0%) had such history. This is same as a study by Annegers et al. [4]

Out of 35 cases that were followed, 4 had one or more of the above-mentioned risk factor. Out of these 4, 2 cases recurred (50%). While in patients without these risk factors only 13.3% cases (2 cases) recurred. Hence, presence of these risk factors increases the rate of recurrence in cases of a single seizure.

American College of Emergency Physician Policy [27] also states that the rate of recurrence is more in those patent who has one or more of these risk factors and should be treated with anti-epileptic treatment irrespective of CT head and EEG.

Out of 6 cases, which had recurred, 1 case recurred within 7 days, 3 cases recurred within 14 days and 2 cases recurred within 28 days. Hence, risk of recurrence decreased with the passage of time. Scotoni et al. [21] and Das et al. [23] has also reported recurrence rate to be much higher in first 3 months.

  Conclusions Top

With the present study following conclusions can be drawn:

  1. Various risk factors associated with risk of new onset seizures are TB, alcohol, developmental delay, old stroke and positive family history.
  2. CT scan head detected structural lesions in only 34% of cases. In 66% cases, it was normal.
  3. EEG detected epileptiform activity in only 8% cases.
  4. Recurrence rate in patients with a single seizure with normal CT and EEG was 24% during 6 months follow-up.
  5. Risk factors associated with recurrence were younger age, longer duration of seizure, abnormal neurological findings, history of developmental delay and alcohol, and family history.
  6. Recurrence rate in patients with normal CT scan and EEG but who had one or more of above-mentioned risk factor was 40% while in patients lacking these risk factors it was only 13.3%.
  7. Most of the recurrence (83.3%) occurred within 1 month. Recurrence rate decreased thereafter.
We do not advise anti-epileptic treatment for a case of new onset single seizure provided there is no associated risk factor for recurrence and CT scan head, and EEG are within normal limits. These patients should be followed carefully for any recurrence. However, there is always a chance of seizure recurrence with positive EEG or MRI in latter decade, anti-epileptics should be considered depending on the patient clinical profile and under special circumstances like immediate postoperative period, bus driver, pilots etc.

But patients with normal CT and EEG, who had one or more factors associated with risk of recurrence the rate of recurrence was 40% and hence should be treated with anti-epileptic drugs.

  References Top

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  [Table 1], [Table 2], [Table 3]

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