Corpus callosotomy for the treatment of intractable epilepsy

44

EpilepsyRes., 2 (1988) 44-50 Elsevier

ERS 00172

Corpus callosotomy for the treatment of intractable epilepsy

Anthony M. Murro” , Herman F. Flanigin” *, Brian B, Gallagher*, Don W. King* and Joseph R. Smith** *Departmentof Neurology, and “*Section of Neurosurgery, Medical College of Georgia, Augusta, GA 3iWf2 (U.S.A.) (Received 3 February 1987; revised received 31 July 1987; accepted 10 August 1987) Key words: Corpus caliosotomy; Seizure; Epilepsy

Twenty-five patients underwent anterior corpus callosotomy (ACC) for treatment of uncontrolled seizures. Two patients died, and 6 patients experienced perioperative complications which resolved. A statistically significant reduction of generalized tonic-clonic seizures (17 patients; P < 0.05) and complex partial seizures (11 patients; P < 0.05) occurred following ACC. A single patient with atonic seizures became free of atonic seizures. Two patients had a >50% reduction in seizures resulting in falls, a single patient became free of episodes of status epilepticus, and in 2 patients the seizures changed from generalized tonic-clonic seizures to hemiconvulsive seizures. Thus ACC appears to decrease the severity and frequency of disabling seizures in some patients with uncontrolled seizures.

INTRODUCTION

METHODS

Corpus callosotomy has improved selected patients with intractable epilepsy by reducing seizure frequency and seizure severity1-7Y’0-‘4*‘6-25.Akinetic seizures24, atonic seizures13, absence seizuresl’, unilateral cerebral atrophy’2*‘3916~17,22 and unilateral EEG abnormalities’2*16*‘7have been associated with a good outcome. Mental retardation3*13,adversive seizures2, and multifocal or diffuse EEG abnormalities12,16,17 have been associated with a poor outcome. We retrospectively studied 25 patients who underwent anterior corpus callosotomy to determine which predictive factors were associated with a good outcome.

Twenty-five patients who met the following criteria were selected for ACC: (1) secondary generalized epilepsy with multiple seizure types or partial seizures of probable frontal lobe origin, (2) seizures were refractory to medical treatment, (3) patients were not candidates for cortical topectomy or temporal lobectomy, and (4) there was potential for.~nctional ~provement with reduction in seizure frequency. Refractory to medical treatment implied frequent seizures despite at least 2 years of sequential drug treatment with anticonvulsant levels in the generally accepted therapeutic range. The potential for improvement was assessed by a team consisting of a neuropsychologist, neurologists, neurosurgeons, and an epilepsy nurse clinician. Preoperative evaiuation included history and examination, CT with contrast, carotid angiography,

Correspondence to: Anthony M. Murro, M.D., Department of Neurology, Medical College of Georgia, Augusta, GA 30912, U.S.A.

0920-121l/88/$03.50 @ 1988 Elsevier Science Publishers B.V. (Biomedical Division)

45 standard EEG investigation, and EEG and video monitoring. EEG investigation included 16-channel recording of interictal and ictai activity from scalp electrodes placed according to the standard lo-20 system. During prolonged monitoring, the video image was recorded directly onto videotape, and 16 channels of EEG were multiplexed and encoded onto one audio channel of the videotape. Replay of the tape allowed correlation of clinical and EEG phenomena. Seizure type was based on the International Classification using historical information and EEG/video documented episodes. Preoperative and postoperative frequency of clinical seizures was based on patient interviews and clinic records. ACC was performed in all cases9. The anterior commissure, hippocampal commissure and massa intermedia were not sectioned. Intraoperative

gross pathology and postoperative complications were noted. Outcome was based on frequency of each seizure type after a minimum of I year of follow-up. In addition, a change in seizure type and a reduction in the frequency of seizures resulting in falls were noted. If preoperative epileptiform activity was primarily diffuse and postoperative epileptiform activity was primarily unilateral, ACC was considered to have resulted in a more lateralized distribution. RESULTS The clinical features of the 25 patients are shown in Table I. Onset of seizures ranged from birth to 39 years, median 5 years. Age at surgery ranged from 6 to 5.5 years, median 25 years. Total follow-

TABLE I Patient characteristics:

age, sex, age at seizure onset, seizure types, exam and seizure etiology

SP = simple partial: GT = generalized tonic; A.abs = atypical absence; GTC = generalized tonic clonic; CP = complex partial; RH = right he~ipa~esis; MR = mental retardation IQ <75

--

______ Pt

1 2 3 4 5 6 7 8 9

10 11 12 13 14

15 16 17 18 19 20 21 22 23 24 25 --

Age (years)lsex

18/M 35/M 19/F 20/M 6/F 23/M 25/F 3X/F 55/F 34iF 2X:F 16/F S/M 26lF 25lM 14/M 26/M 21/M 19/M 20/M 35/M 25/F 20/M 47/M 43/F

Age at onset ---

4 1
____-.-

Exam

EIiology

Seizure type

RH Normal MR Normal RH, MR MR MR Normal Normal MR MR MR MR Normal

Meningitis Trauma Rubella, asphyxia Unknown Unknown Encephalitis Asphyxia Prematurity Unknown Unknown Unknown Asphyxia Unknown Trauma Asphyxia Unknown Unknown Asphyxia Trauma Unknown Encephalitis Asphyxia Unknown Unknown Unknown

GTC, SP CP, SP GTC, SP GTC GTC, ATQ GTC, SP GTC GTC, CP GTC GTC GTC, CP GTC, CP GTC, CP CP GTC, GT GTC, GT GTC. CP. A.abs GTC. CP GTC CP CP CP GT. A.ahs GTC, CP CP

MR

MR Normal MR MR Normal MR MR MR Normal Normal

46 up ranged from 12 to 67 months, median 29 months, Fifteen patients had an IQ <75, and 2 patients had infantile hemiplegia. Seizure types included generalized tonic-clonic in 18 cases, complex partial in 13 eases, simple partial in 4 cases, generalized tonic in 3 cases, atypical absence in 2 cases and generalized atonic in 1 case. Etiological factors included CNS infection in 4 cases, perinatal complications in 7 cases, head trauma in 3 cases, and no apparent etiology in 12 cases. Two etiologic factors were present in 1.case. Preoperative CT abnormalities included diffuse atrophy in 3 cases, multifocal atrophy in 2 cases, hemispheric atrophy in 2 cases, and focal atrophy in 2 cases (Table II). The preoperative interictal EEG demonstrated generalized epilept~form dis-

charges alone in 3 cases, multifocal epileptiform discharges alone in 3 cases, generalized and multifocal epileptiform discharges in 16 cases and generalized and unifocal discharges in 3 cases (Table II>. Three patients (nos. 4,9 and 10) had rhythmic b~yn~hrono~s 2.5-4 Hz spike and wave activity precipitated by h~e~entilation, and patient no. 10 demonstrated a phot~onvulsive response. However, all 3 of these cases had background slowing consistent with secondary instead of primary generalized epilepsy. ACC resulted in a statistically significant reduction in generalized tonic-clonic seizures (17 patients; P < 0.05;signed rank test; Table III>* Three of these patients either became free of or developed rare seizures, and 4 patients had a

>50% reduction in seizure frequency. There was also a reduction in complex partial seizures following ACC (11 patients; P < 0.05; signed rank test; Table IV). One of these patients became free of seizures, and 4 had a >50% reduction in seizure frequency. None of the patients with partial simple seizures had a significant change in seizure frequency (Table V). The single patient with atonic seizures became free of seizures, while the remaining seizure types did not change significantly (Table VI). Six of 8 patients without mental retardation (IQ >7S) had a >50% reduction in 1 seizure type compared to only 6 of 15 patients with mental retardation (IQ ~7.5). Both cases of infantile hemiplegia had a >50% reduction in 1 seizure type. Eight of 13 patients with seizure onset at or before age 5 had a >50% reduction in 1 seizure type compared to only 4 of 10 with a seizure onset after age 5.

There was no apparent relationship between preoperative or postoperative EEG and outcome. A change from generalized tonic-clonic to hemiconvulsive seizures occurred in 2 patients (nos. 3 and 6). A greater than 50% reduction in seizures resulting in falls occurred in 2 patients (nos. 12 and 14). Patient 9 became free of episodes of generalized status epilepticus. Less impairment in consciousness with partial complex seizures was reported by patients 18 and 21. Two patients died postoperatively. One death (no. 25) resulted from putmonary complications following an unexplained intraoperative bleeding diathesis. This patient was not taking valproic acid, and PT and PTT studies were normal preoperatively. The second death (no. 24) occurred 9 days after surgery and was due to pulmonary embolus and DIC following surgery. Significant postoperative complications included intracranial hemorrhages in 2 cases (nos.

48 TABLE II CT and EEG results

GEN = generalized; RF = right frontal; LF = left frontal; RT = right temporal; LF = left temporal; RC = right central; RP = right posterior; LC = left central; LP = left posterior; PCR = photoconvulsive response; * = patient died; Lat = lateralized distribution of epileptiform activity. PI

Preop. CT scan

Preop. EEG slowing

Preop. epileptiform activity

Postop. epileptiform activity

1 2 3 4 5 6 7 8 9 10 11 12 13 14 1.5 16 17 18 19 20 21 22 23 24 25

Atrophy hemisphere Normal Normal Normal Atrophy hemisphere Normal Normal Atrophy temp. lobe Atrophy diffuse Normal Normal Normal Normal Atrophy multifocal Normal Normal Atrophy diffuse Atrophy temp. lobe Normal Normal Atrophy multifocal Hydrocephalus Normal Normal Atrophy diffuse

GenR>L None GenL>R Gen Gen GenR>L Gen Gen Gen Gen, LF Gen, LF RF None Gen Gen Gen Gen Gen RF RF GenR>L RF>LF GenR>L None Gen, RT, LT

Gen L > R, RC, LC, RP, LP RF, RT, LF, LT Gen, RF, LF Gen Gen, LF, LP RF, RT, LT Gen, RF, LF Gen, RT, LT Gen Gen RT, LT, LF, PCR Gen, LF, LT Gen, RF Gen, RF, LF, RT, LT, RP, LP Gen, LT, RC, LC Gen, RF, LF, LT Gen, RC, RF, LF Gen, RF, LF, RT, LT Gen, RF, LF, LT RT, LT, RC, LC Gen, RF Gen, RF Gen, RF, LF, RT, LT Gen, LT, RF Gen Gen, RF, LT

LatRorL Unchanged Unchanged Unchanged Lat L Unchanged Unchanged LatRorL LatRorL Unchanged LatRorL Unchanged Unchanged Unchanged Unchanged Unchanged Unchanged LatRorL Unchanged Lat R LatRorL LatRorL Unchanged *

8 and 9), both of whom recovered without deficit; cerebral infarction with mild hemiparesis in 1 case (no. 19); and infection in 3 cases. The infections included 2 superficial wound infections (nos. 1 and 11) and an infected bone flap (no. 7), all of which recovered with antibiotic treatment. DISCUSSION The results of this study confirm previous studies demonstrating a beneficial effect of corpus callosotomy in selected patients with intractable epilepBeneficial effects occur through resy 1-7~10-14V16-25. duction in seizure frequency and a change to seizures of a less disabling type. The favorable response of generalized tonic-

clonic seizures (GTC) to corpus callosotomy reported in this series confirms results obtained in other series. Gates et al.” reported cessation of GTC seizures in 12 of 17 cases and a greater than 80% reduction in an additional 4 cases. Geoffroy et al. l2 reported cessation of GTC seizures in 4 of 5 cases and greater than 80% reduction in the remaining case. Reeves and O’Leary” reported cessation of GTC seizures in 6 of 10 cases and a greater than 80% reduction in the remaining 4 cases. Rayport et al.‘* reported cessation of GTC seizures in 2 of 6 cases and a greater than 50% reduction in an additional 2 cases. Amacher’ reported cessation of GTC seizures in 3 of 4 cases. The favorable response of complex partial seizures (CP) to corpus callosotomy reported in this

49 TABLE III

TABLE V

Outcome of patients with generalized tonic clonic seizures

Outcome of patients with simplepartial seizures

Pt

1 3 4 5 6 7 8 9

10 11 12 13 15 16 17 18 19 24

Preop. frequency

Postop. frequency

(per month)

(per month)

30 30 8 rare 29 30 13 12 4 2 4 6 6 62 0.25 0.5 11 1

0

rare rare rare 3 4 2 3 2 1 4 6 6 62 0.25 0.5 30 *

Follow-up (months)

30 32 40 30 29 35 67 33 22 18 18 18 28 19 44 21 20 *

rare = l-2 seizures/year; * patient died; P < 0.05 (signed rank test).

series confirms the results obtained in other series. Reeves and O’Leary” reported cessation of CP seizures in 7 of 10 cases and a greater than 80% reduction in an additional 2 cases. Gates et al.” re-

TABLE IV Outcome ofpatients with complexpartial seizures Pt

2 8 12 13 14 17 18 20 21 22 11 24 25

Preop. frequency

Postop. frequency

Follow-up

(per month)

(per month)

(months)

75

0

360

13 16 3 106 4 90 1 3 180 4

120 10 270 4 90 1 2 180 3 10 15

* *

* Patient died; P < 0.05 (signed rank test).

12 67 18 18 37 44 21 30 41 21 18 *

- = seizure type not present prior to surgery. Pt

1 2 3 6

Preop. frequency

Postop. frequency

Follow-up

(per month)

(per month)

(months)

4 75 _ -

7 75 13 2

30 12 32 29

ported cessation of CP seizures in 6 of 21 cases and a greater than 50% reduction in an additional 4 cases. Clinical factors associated with a better outcome included absence of mental retardation, infantile hemiplegia, and age of seizure onset at or below the age of 5. Similar findings have been reported for mental retardation3T13 and infantile hemiplegial2,13,16,17,22. Good outcome in patients with a seizure onset at age 5 or less was present in 6 of 7 cases in one series12 and in 3 of 4 cases in another series16. Improvement noted for patients with secondary generalized epilepsy is consistent with experimental studies demonstrating the role of the corpus callosum in the contralateral spread of seizure activity8~15. Complications reported in other series have included parasagittal infarction, epidural hematoma, aseptic meningitis, hydrocephalus, bacterial meningitis, monoparesis, hemiparesis, wound infection, worsening of seizures and death2-7,

TABLE VI Outcome of patients with atonic, tonic and atypical absence seizures Pl

5 15 16 23 17 23

Seizure

Preop .

Postop

Follow-

type

frequency

frequency

(per month)

(per month)

up (months)

Atonic Tonic Tonic Tonic A.abs A.abs

500

0

30

126

90

28

19 17 44 17

60

60

45

45

10 49

10 50

50

10-14~‘6-25. In our series, 2 patients died, and reversible complications occurred in 6 patients. In conclusion, selected patients with secondary generalized epilepsy benefited from corpus callo-

sotomy. Clearly, risks and benefits should be evaluated in each patient, and corpus callosotomy should be reserved for severely affected patients with intractable epilepsy.

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