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MRI

Should an MRI be obtained?

Author, date, country, and industry of funding Patient Group Strength of Evidence (GRADE) Research design Significant results Limitations

(Arthur et al., 2008)

USA

Children age 6-14 years

N= 150

(349 were recruited)

Single afebrile seizure followed up at 9, 11 and 27 months.

Provider decided who got MRI

 

Low

Prospective cohort

Followed for at least 27 months

Children with absence, myoclonic or prior unrecognized seizure were excluded.

There was a recurrence rate of 66.4%

An abnormal EEG had no association with seizure recurrence at 9, 18, or 27 mo (p = 0.1806, p = 0.2792, and         p =0.2379, respectively)

 

Recur By (%)

9 mo

18 mo

27 mo

Normal EEG n=55

50.9

56.4

60

Abnl EEG

 n= 95

62.1

65.3

69.5

Normal MRI

n=87

59.8

65.5

67.8

Non signif. MRI

n=18

33.3

33.3

44.4

Signif. MRI

n= 20

80

80

80

A “significant” MRI abnormality (16% of subjects) was associated with increased risk of recurrence at 9 mo (p = 0.0389), but not 18 or 27 months

They do not recommend MRI after first seizure, because it is not predictive.

Of the 349 recruited into the larger study, 189 subjects met the criteria for this study.

150 had EEG performed

125 subjects had MRI performed.

(Chan et al., 2010)

Singapore

Children aged 1 month to 15 years with first  afebrile seizure

108 with ≥ 2 afebrile seizure and 103 with first afebrile seizure

Very Low

Population Survey

 

 

1st SZ

Epilepsy≥ 2 SZ

P value

Develop- mental exam (normal)

93%

87%

P=0.046

Neuro exam (normal)

98%

92%

P=0.016

EEG (abnl)

36.9%

75%

P≤0.005

CT/MRI (abnl)

33%

20.3%

NR

 

 

Population based study that looked at the epidemiology of afebrile seizure.

(Hsieh et al., 2010)

USA

317 infant subjects (range 1-24 months) urban population

Low-It is a cohort study based on a clinical guideline.

Prospective cohort

EEG (all subjects) abnormalities were found in half

CT (298/317 obtained) abnormalities were found in a third

MRI (182/ 317 obtained) abnormalities were found in 57%

Of the 193 normal CTs, 97 underwent MRI of which 32 (33%) had an abnormal MRI

The majority had more than one seizure upon presentation.

The incidence of seizures lasting longer than 20 minutes was 8.5%

30 subjects had a history of prematurity.

Increased likelihood of obtaining an MRI in younger infants.

 

Kodaphanhadeh 2006 Iran

125 subjects, children mean age 53 ±48 months (range-

1 month-15 years)

Low

Retrospective case series –no control group. Excluded those with seizures > 30 minutes or electrolyte abnormalities

Report on CT scan and MRI within the first hours of arrival

Neuro-imaging was obtained in 119 subjects (95%)

Emergent CT was performed in 108 (91%) and MRI in 11 (9%)

Neuro-imaging was normal in 107 (90%) of subjects.

Clinical significant results were found in 12 subjects (10%)

10 of the 12 subjects with abnormal findings had abnormal neurological examination.

 

Study design.

Rauch 2008

USA

75 children aged 0-18 years Included those with MRI at admission and afebrile seizure

Very Low- quality study

Retrospective cohort – chart review. Excluded genetic anomaly, history of seizure, CNS pathology

Below 12 years of age sedated for MRI

 71 subjects (95%) had LOS increased by one day for the MRI

13 subjects (17%) had abnormal MRI results; 1/13 had an abnormal neurological exam

No changes in treatment based on the MRI occurred.

There was a 53% fall in the number of MRI obtained from the first to second year as the results from the quality project were made known and changed practice.

Sharma 2003 USA

500 subjects with new-onset afebrile seizure median age (16 mo range (0-21 years))

 

Retrospective

Neuro-imaging was performed in 475/500. 25 subjects were not imaged.

Of the subjects who were scanned, CT was performed in 454/475, and MRI was performed in 21/475.

437/475 had neuro-imaging while in the ED. And 13 had neuro-imaging after the ED visit but within 72 hours of the visit.

Normal imaging results were reported in 395/475 subjects. [83%]

Clinically insignificant results were reported in 42/475 [9%]

Clinically significant events were reported in 38/475 subjects [8%]

Using Partition analysis, 3 variables partitioned the subjects into 4 groups

Variables

Presence of pre disposing condition, focality of the seizure and age

Groups

Predisposing condition- High risk

No predisposing condition

Non-focal seizure- low risk

Focal seizure- age dependent

Age > 33 months low risk

Age < 33 months high risk

5/6 subjects who fell in the low risk group by partition analysis had abnormal findings on physical/neurological exam.

One subject subsequently diagnosed with grey matter heterotopias had a normal physical and neurological exam.

Retrospective design

 

These guidelines do not establish a standard of care to be followed in every case. It is recognized that each case is different and those individuals involved in providing health care are expected to use their judgment in determining what is in the best interests of the patient based on the circumstances existing at the time. It is impossible to anticipate all possible situations that may exist and to prepare guidelines for each. Accordingly these guidelines should guide care with the understanding that departures from them may be required at times.