The Chalfont Seizure Severity Scale can be used to gauge the clinical severity of a type of seizure for a patient. This can be used to help gauge the effectiveness of anti-epileptic drugs during clinical trials. The scale was developed at the Chalfont Centre for Epilepsy in Buckinghamshire, England.
Classification of seizure type: according to the International League Against Epilepsy Classification (Epilepsia 1981; 22: 489-501), including:
(1) simple partial
(2) complex partial
(3) partial seizures evolving to generalized tonic-clonic convulsion
(4) absence
(5) myoclonic
(6) clonic
(7) tonic
(8) generalized tonic-clonic
(9) atonic
(10) unclassified
Parameters:
(1) loss of awareness
(2) if loss of awareness, warning
(3) drop or spill held object
(4) fall to ground
(5) injury
(6) incontinence for feces and/or urine
(7) automatism
(8) convulsion (clonic jerking of limbs)
(9) duration of seizure
(10) time to return to normal from onset (time before able to resume preseizure activity)
(11) adjustments if initial score 0
(12) adjustment for occurrence only during sleep
|
Parameters |
Findings |
Points |
|---|---|---|
|
loss of awareness |
no |
0 |
|
|
yes |
1 |
|
warning |
present with loss of awareness |
0 |
|
|
absent with loss of awareness |
1 |
|
|
no loss of awareness |
0 |
|
drop or spill held object |
no |
0 |
|
|
yes |
4 (max) |
|
fall to ground |
no |
0 |
|
|
yes |
4 (max) |
|
injury |
no |
0 |
|
|
yes |
20 (max) |
|
incontinence |
no |
0 |
|
|
yes |
8 (max) |
|
automatism |
no |
0 |
|
|
mild (not socially disabling: chew, swallow, fiddle) |
4 (max) |
|
|
severe (socially disabling: shout, undress, run, hit) |
12 (max) |
|
convulsion |
no |
0 |
|
|
yes |
12 (max) |
|
duration of seizure |
< 10 seconds |
0 |
|
|
10 to 59 seconds |
1 |
|
|
1 to 10 minutes |
4 |
|
|
> 10 minutes |
16 |
|
time to return to normal |
< 1 minute |
0 |
|
|
1 – 10 minutes |
5 |
|
|
11 to 30 minutes |
20 |
|
|
31 to 60 minutes |
30 |
|
|
1 to 3 hours |
50 |
|
|
> 3 hours |
100 |
Some items are adjusted for the relative frequency of their occurrence as follows:
|
Percent of Time Event Occurs |
Fractionation of Items (those indicated by "max") |
|---|---|
|
1 – 25% |
0.25 * (max value) |
|
26 – 50% |
0.50 * (max value) |
|
51 – 75% |
0.75 * (max value) |
|
76 – 100% |
1.00 * (max value) |
severity score =
= SUM(points for all of the parameters)
|
Adjustments to Score |
Action |
|---|---|
|
score 0 (brief aura) |
add 1 |
|
if seizure occurs only during sleep |
divide by 2 |
Interpretation:
• minimum severity score: 0.5
• maximum severity score: 178
• The higher the score, the more the severe the seizure's impact on the patient.
• Up to 3 seizure types are scored.
Limitations:
• The score showed no change in a clinical trial of tiagabine. Subsequently the scale was revised to become the National Hospital Seizure Severity Scale (NHS3).
Purpose: To evaluate the severity of a seizure in a patient using the Chalfont Seizure Severity Scale.
Specialty: Neurology
Objective: severity, prognosis, stage
ICD-10: G40,
