|
Indian Pediatr 2013;50:
753-757 |
|
Phenobarbitone versus Phenytoin for
Treatment of Neonatal Seizures: An Open-label Randomized
Controlled Trial
|
Garima Pathak, Amit Upadhyay, Umesh Pathak, *Deepak
Chawla and †Sneh P Goel
From the Department of Pediatrics, LLRM Medical College,
Meerut;*Department of Pediatrics, Government Medical College,
Chandigarh; and †Department of Pediatrics,
Subharti Medical College, Meerut, UP, India.
Correspondence to: Dr Amit Upadhyay, Department of Pediatrics, LLRM
Medical College, Meerut, India.
Email: [email protected]
Received: January 14, 2012;
Initial review: February 06, 2012;
Accepted: November 14, 2012.
PII:
S097475591200051
|
Objective: To compare the efficacy of phenobarbitone and phenytoin
for treatment of neonatal seizures in term and near-term neonates.
Design: Open labeled randomized controlled trial.
Setting: Neonatal intensive care unit of a level
II unit from India, from November 2008 to September 2009.
Participants: All term and late pre-term neonates
admitted with clinically apparent seizures and not having any transient
metabolic disorders (hypoglycemia or hypocalcemia) were randomly
assigned.
Intervention: Phenobarbitone (n=54) or
phenytoin (n=55) intravenously 20 mg/kg/dose over 20-30 min.
Neonates whose seizures were not controlled by the assigned drug were
then crossed over to be treated with other drug in same dose.
Primary outcome variable: Clinical control of
seizures (seizure free period of 24 hours after giving anticonvulsant).
Results: Baseline characteristics including mean
birthweight, gestation age and sex were comparable in both groups.
Seizures were controlled in 8 of the 55 (14.5%) neonates who received
phenytoin, as compared to 39 of 54 (72.2%) neonates who received
phenobarbitone (P <0.001). In babies not responding to assigned
drugs, after cross-over to the other drug, seizure control was achieved
in 44/55 (80%) of the neonates assigned to receive phenytoin first as
compared to 49/54 (91%) of those assigned to receive phenobarbitone
first (P=0.014). After maximum dose of phenobarbitone seizures
were controlled in 49/55(89%) in phenytoin group and 52/54 (96%) in
phenobarbitone group (P<0.05).
Conclusion: Phenobarbitone is more efficacious
than phenytoin in control of clinical seizures in term or near-term
neonates, irrespective of etiology.
Key words: Convulsion, Phenobarbitone, Phenytoin, EEG.
|
Neonatal seizures are often treated with
phenobarbitone or phenytoin
[1-6], equally but incompletely. Efficacy of both the drugs in neonates
is reported to be (30-50%) for abolition of electrical seizures [4].
However, in developing countries, most units have no access to
electroencephalogram (EEG) monitoring in NICU. We intended to compare
efficacy of phenobarbitone and phenytoin in the treatment of clinically
apparent seizures in term and late pre-term neonates.
Methods
This open-label randomized controlled trial was
conducted at a Level II neonatal unit of a government medical college in
India.
Inclusion criteria: All term or near term
neonates ( ³35
weeks of gestation) admitted with clinically apparent seizures not
responding to treatment of hypoglycemia, hypocalcemia and other
metabolic disorders. Clinical criteria for diagnosis of neonatal
seizures were: (i) clonic movement which could be unifocal,
multifocal or generalized (ii) tonic posturing with or
without abnormal gaze (iii) subtle seizures and
spontaneous paroxysmal, repetitive motor or autonomic phenomenon like
lip smacking, chewing, paddling, cyclic movements or respiratory
irregularities. Three resident doctors posted in NICU were taught
diagnosis and classification of seizures with an educational video and
they recorded all seizures (with time) on a pre-designed proforma.
Seizures responding to correction of hypoglycemia, hypocalcemia or
any other metabolic disorder, and babies with major congenital
malformation or myoclonic jerks were excluded.
Randomization, allocation concealment and blinding:
Block randomization of 112 numbers in blocks of 4 was done by using
computer generated random numbers. They were put in serially numbered
opaque envelopes and sealed. This was done by a person not involved in
study. These pre-numbered sealed envelopes were opened to determine the
anticonvulsant to be given to the baby. Our trial was an open label
trial, so the doctors and nursing staff were aware of the treatment
assignments. However, the EEG technicians and neurologist reporting the
EEG were blinded to the intervention.
Protocol for giving anticonvulsants: Details of
name, age, sex, weight, head circumference and length were recorded on a
pre structured proforma. Patency of airway, breathing and circulation
was ensured based on standard guidelines [7]. After a cannula was
secured, blood sugar, serum calcium and blood for other tests was drawn.
Hypoglycemia was defined as blood sugar <45mg/dL [7]. Hypocalcemia was
defined as ionized calcium <4 mg/dL (1mmol/L) in late preterm and less
than 1.2 mmol/L (ionic) in term neonates [7]. If seizures persisted even
after correction of hypoglycemia and hypocalcemia, babies were
randomized to either phenytoin (plan A) or phenobarbitone (plan B). In
plan A, baby was loaded with injection phenytoin at
20mg/kg slow IV infusion over 30 min at a rate of 1mg/kg/min. Cardiac
rate, rhythm and blood pressure was monitored during the infusion. If
seizure persisted, the babies were crossed over to IV phenobarbitone. In
Plan B, babies were loaded with injection phenobarbitone at 20 mg/kg
slow IV infusion over 30 min under cardiorespiratory monitoring. If
seizure persisted, baby crossed over to receive IV phenytoin in above
dose. If seizure persisted after two drugs, baby was reloaded with IV
phenobarbitone @ 10 mg/kg each to a maximum of 40 mg/kg and then a third
line drug like midazolam was used i.v at 0.1mg/kg/dose. Administration
of the drug was discontinued if respiratory depression (cessation of
respiration for more than 20 seconds, or less than 20 seconds associated
with cyanosis or bradycardia), hypotension (mean blood pressure less
than 35 mm of Hg) or bradycardia (heart rate <80/minute) developed after
use of either of the drugs.
Once the baby was seizure-free for five days,
anticonvulsants were stopped in the same order as they were started
except phenobarbitone. IV phenobarbitone was changed to oral once baby
was on 50% of enteral feeds. Phenobarbitone was stopped last at
discharge if neurological examination was normal and EEG demonstrated no
electrical seizures. If neurological examination or EEG was not normal
or not done then phenobarbitone was continued after discharge, and baby
was re-evaluated at age of 1 month and baby managed according to unit
protocol [7] in consultation with a neurologist. However, weaning or
discontinuation of anticonvulsants was the prerogative of the unit in
which the baby was admitted. EEG was recorded after control of all
clinical seizures for 48-72 hours (when baby was hemodynamically stable)
after transporting the baby to the EEG room.
Cessation of clinical seizure activity was primary
outcome variable of this study. Secondary outcome variables were (i)
survival at discharge, (ii) neurodevelopment outcome at 3 months
(Amiel-Tieson method), (iii) time taken to control seizures, and
(iv) EEG control of seizures. Neurological examination was done
in all babies at discharge. It included examination of overall activity,
response to stimuli, ability to suck and swallow, active and passive
tone of neck and trunk muscles and neonatal reflexes ( Moro, traction
,and habituation). Examination at 3 months was done by examination of
tone by Amiel Tieson method (adductor angle, popliteal angle,
dorsiflexion angle and scarf sign). Achievement of milestones like
social smile, recognition of mother, neonatal reflexs (Moro’s and
grasp), head circumference and persistence of seizure were evaluated.
For those babies who could not come for follow up, telephonic interview
of parents and local practitioners was conducted. They were asked about
age, specific developmental milestones, weight gain, feeding,
persistence of seizures and over all perception of parents about
neurological status and development. Neurodevelopment outcome was
considered abnormal if tone of baby was outside of Amiel Tieson score
range and if no social smile or recognition of mother was noted by 3
months.
Statistical analysis: To detect 30%
reduction in seizure control with phenobarbitone as compared to
phenytoin with power of 80% and a
error of 0.05, at least 50 babies were required in each group. We
decided to include 10-12 babies extra to adjust for protocol deviation,
if any. Statistical analysis was done using intention to treat
analysis. Results were analyzed using SPSS 13 software. Continuous data
with normal distribution were analyzed by student t test and
non-normally distributed data by Mann-Whitney Test. Categorical data was
analyzed by chi-square test or Fischer exact test, where applicable.
Results
A total of 115 babies with clinically apparent
seizures were screened during the study period. Out of them, 6 were
excluded (3 refused to participate, 2 had major congenital malformations
and 1 had seizure responding to documented hypocalcemia). Of the
remaining 109 babies, 55 were randomized to phenytoin group (plan A) and
54 were randomized to phenobarbitone group (plan B). Baseline
characteristics and seizures characteristics were comparable in both
groups (Table I). In case of multiple types of seizures in
a baby, he was classified on the basis of first seizure type only.
TABLE I Baseline Characteristics of Study Population
Parameters |
Phenytoin |
Phenobarbitone
|
|
group (n=55) |
group (n=54) |
Gestational age* (wk) |
38.6 (1.45) |
38.09 (1.87) |
Weight* (kg) |
2.71 (0.4) |
2.55 (0.5) |
Male sex |
39 (70.9) |
40 (74.1) |
No of extramural deliveries
|
30 (70.9) |
36 (67.0) |
HIE stage 2 (n=42) |
21 (38.2) |
21 (38.9) |
HIE stage 3 (n=44) |
26 (47.3) |
18 (33.3) |
Cause of seizures |
Meningitis (n=18) |
7 (12.7) |
11 (20.4) |
Intracranial bleed (n=2) |
1 (1.8) |
1 (1.9) |
Kernicterus (n=4) |
1 (1.8) |
3 (5.6) |
Type of seizure
|
Subtle |
27 (49) |
24 (44) |
Tonic |
24 (43) |
20 (37) |
Clonic |
6 (10.9) |
8 (14) |
in No. (%); *mean (standard deviation). |
Cessation of clinical seizure was observed in 8 of
the 55 (14.5%) neonates who received phenytoin and 39 of 54 (72.2%)
neonates receiving phenobarbitone first (P<0.001). Babies in whom
seizure control was not achieved with first drug, after cross-over,
seizure control was achieved in 44/55 (80%) of the neonates assigned to
receive phenytoin first and 52/54 (96.3%) of those assigned to receive
phenobarbitone first (P=0.014). After maximum dose of
phenobarbitone, seizures were controlled in 49/55 (89%) in phenytoin
group and 52/54 (96%) in phenobarbitone group (P<0.05).
Median (range) time taken to control all seizures was
30 min (10 min–48 h) in hypoxic ischemic encephalopathy (HIE) stage II,
60 min (10 min–6 d) in HIE stage III, 52 min (15min-24 h) in
meningitis, and 11 hours (30 min-3 h) in intracranial hemorrhage. There
was no significant difference in seizure control in the two groups (P
>0.05).
Out of 109 babies enrolled in the study, 29 expired
during NICU stay and 80 were discharged. Of these 80, 13 were lost to
follow up, and 67 babies were followed at 3 months. Mortality and normal
outcome was comparable in both groups. Normal neurological outcome at 3
months was seen in 80% in HIE II, 75% in meningitis and 11% in HIE III.
After clinical control of seizures, EEG was done in
72 babies out of which 66 (91.6%) had normal EEG record and 6(8.4%) had
abnormal EEG record. There was no significant difference in incidence of
abnormal EEG records in the two groups. The common abnormalities noted
were electrical spikes, and background abnormalities like "burst
suppression" pattern or low electrical voltage.
Respiratory depression was found in 3 babies after
phenobarbitone and 2 babies after midazolam. Bradycardia was seen in 2
babies with use of phenytoin. During hospital stay, 29 (26%) babies
expired (16 in phenytoin group, and 13 in phenobarbitone group, P
>0.05). 23 of these 29 deaths were in babies with HIE stage III. Of the
remaining, 4 were in HIE stage II, 1 each had meningitis and 1 had
kernicterus. None of these mortalities were within 4 hours of giving
drugs so likely to be unrelated to drugs used, but due to underlying
condition. Serum levels of any of the drugs could not be done.
Discussion
Our study demonstrated that phenobarbitone is more
efficacious than phenytoin in control of clinical seizures in term or
near term neonates irrespective of the etiology. Superiority of
phenobarbitone was observed both when given as a single drug at 20 mg/kg
and even after crossover between two groups. Clinical control of seizure
was probably accompanied by electrical control of seizures in majority.
No significant side effect could be directly related to any of the drugs
used.
Our study differed from Boylan, et al. [3],
who demonstrated that phenobarbitone achieved electrical control
of seizures in only 29% as a first line anticonvulsant in whom the
background EEG was significantly abnormal. However, our study did not
record background EEG signals, so their results may be difficult to
compare to this study. Our study differed from Painter, et al.
[4], who demonstrated that phenobarbitone and phenytoin are equally but
incompletely effective as anticonvulsant in neonates. Control of
electrical seizures was noted in about 45% babies with either drug and
about 60% when combined [4]. However, they did not describe the efficacy
of clinical control of seizures, so it is difficult to compare their
results to ours. They also did not find any significant side effect
related to any of the drugs used. Similar to our results, Gilman, et
al. [8] reported 75% control of clinical seizure with phenobarbitone
and 85% when combined with phenytoin. There are logistic advantages of
use of phenobarbitone over phenytoin (i) it enters CSF
(presumably brain) rapidly and with high efficacy, (ii) the serum
level is predictable after the dose, (iii) it can be administered
intramuscularly as well as intravenously for acute therapy and (iv)
maintenance therapy is easily accomplished with oral therapy [5].
Mirzahi and Kellway have suggested that diagnosis of
seizures may be inaccurate without EEG confirmation [9].
Murray and Boylan have demonstrated that only 1/3rd
of neonatal EEG seizures display clinical signs and rest 2/3rd
of these clinical manifestations are unrecognized by experienced
neonatal staff. In recognition and management of neonatal seizures,
clinical diagnosis is not enough [10]. The issue of end point of
seizures is debatable. Most authorities recommend electrical control of
seizure using 24-hour video EEG, but neither the machine, nor cerebral
function monitoring (CFM), or the specialist interpreters are readily
available. CFM monitoring, though easier to use and interpret is not
sensitive enough to detect all seizures. Also, numerous experimental
studies on adult and neonatal animal brain have shown that subtle
seizure like activity may commonly originate from inferior colliculi of
neonatal brainstem. Inferior colliculi of neonatal brain is particularly
sensitive to injury by hypoxic ischemic encephalopathy which is the
commonest cause of seizures in neonates (and in our study as well)
[11-13]. So, such clinically apparent seizures are not likely to have an
EEG correlate. Mizrahi and Kellaway have reported that subtle seizures
in term and near term neonates have only inconsistent association with
EEG seizure activity in as many as 85% of infants. They have also
reported that approximately 85% of generalized tonic seizures in full
term neonates are not associated with electrical activity and have poor
response to anticonvulsants [10]. However, as stated earlier, in a
overwhelming majority of neonatal units in both developed and developing
world, bedside EEG is not available due to lack of expensive CFM
equipments. Thus studies based on abolition of clinical seizures, may
have more external validity and generalisability in NICUs, especially in
third world countries.
In our study, 26% babies expired during NICU stay.
Over two third of these babies were born at home and did not receive any
resuscitation at birth. High mortality was probably due to babies coming
in advanced stage of illness and seeking late care in a level II unit,
without facility for ventilation. However, previous studies have also
reported similar high mortality with HIE stage III [14]. Our 3 month
outcomes are also somewhat comparable to other studies. Robertson and
Finer reported that neurological outcome was 100% normal in mild HIE,
71% normal in moderate HIE, while none were normal in severe HIE [15].
According to previous studies, in meningitis by both group B
streptococcus and gram negative bacilli, 50% survivors had no sequelae,
40% had mild to moderate sequelae while only 10% had severe sequelae
[16-18]. Lack of blinding of clinical outcomes, inability to monitor
serum drug level and cerebral functions and only short term follow up
were the limitation of our study.
Contributors: All authors were equally involved
in all aspects of the study and manuscript prepration.
Funding: Nil; Competing interests: None
stated.
What is Already Known?
• Phenobarbitone and phenytoin are equally
but incompletely effective as anticonvulsant in neonates.
What this Study Adds?
• Phenobarbitone is significantly more efficacious than
phenytoin in control of clinical seizures in term or near term
neonates irrespective of etiology.
|
References
1. Vanrman C, Darrvish H. Efficacy of phenobarbital
in neonatal seizures. Can J Neurol Sci.1985;12:95-9.
2. Lockman LA, Kriel R, Zaske D, Thompson T, Virnig
N. Phenobarbital dosage for control of neonatal seizures. Neurology.
1979;29:1445-9.
3. Boylan GB, Rennie JM, Pressler RM, Wilson G,
Morton M, Binnie CD. Phenobarbitone, neonatal seizures, and video-EEG.
Arch Dis Child Fetal Neonatal Ed. 2002;86:165-7.
4. Painter MJ, Scher MS, Stein MD, Armatti S, Gardner
JC. Phenobarbitone compared with Phenytoin for neonatal seizures. N Engl
J Med.1999;341:485-9.
5. Volpe JJ. Neonatal Seizures. In: Neurology
of the Newborn. Philadelphia: WB Saunders; 1999. P.172-225.
6. Massingale TW, Buttross S. Survey of treatment
practices for neonatal seizures. J Perinatol. 1993;13:107-10.
7. Jeeva Sankar M, Agarwal R, Aggrawal R, Deorari AK,
Paul VK. Seizures in the newborn. Indian J Pediatr. 2008;75:149-55.
8. Gilman JT, Gal P, Duchowny MS, Weaver RL, Weaver
RL, Ransom JL. Rapid sequential phenobarbitone treatment of
neonatal seizures. Pediatrics. 1989; 83:674-8.
9. Mizrahi EM, Kellaway P. Characterization and
classification of neonatal seizures. Neurology. 1987; 37:1837-44.
10. Murray DM, Boylan GB, Ali I, Ryan CA, Murphy BP,
Connolly S. Defining the gap between electrographic seizure burden,
clinical expression and staff recognition of neonatal seizures,
Arch Dis Child Fetal Neonatal Ed. 2008; 93: F187-91.
11. McCown TJ, Breese GR. The development profile of
seizure genesis in the inferior collicular cortex of the rat: Relevance
to human neonatal seizures. Epilepsia. 1992;33:2-10.
12. Ranck JB, Windle WF. Brain damage in monkey,
Macaca Mulatta, by asphyxia neonatorum. Exp Neurol. 1959;1:130.
13. Faro MD, Windle WF. Transneuronal degeneration in
brains of monkeys asphyxiated at birth. Exp Neurology. 1969; 24: 38-53.
14. Dað Y, Fýrat AK, Karakaº HM, Alkan A, Yakýncý C,
Erdem G. Clinical outcomes of neonatal hypoxic ischemic encephalopathy
evaluated with diffusion-weighted magnetic resonance imaging. Diagn
Interv Radiol. 2006;12:109-14.
15. Robertson C, Finer N. Term infants with hypoxic–
ischemic encephalopathy outcome at 3.5 years. Dev Med Child Neurol.
1985;27: 473-84.
16. Holt DE, Halket S, de Louvois J, Harvey D.
Neonatal meningitis in England and Wales, 10 years on. Arch Dis Child
Fetal Neonatal Ed. 2001;84: F85-9.
17. Stevens JP, Eames M, Kent A, Halket S, Holt D,
Harvey D. Long term outcome of neonatal meningitis. Arch Dis Child.
2003;88:179-84.
18. Klinger G, Chin CN, Beyenne J, Perlman M.
Predicting the outcome of neonatal bacterial meningitis. Pediatrics.
2000; 106: 477-82.
|
|
|
|