Factors of morbidity in hemispherectomies: Surgical technique×pathology

Original article

Factors of morbidity in hemispherectomies:

Surgical technique!pathology

Antonio Nogueira de Almeida*, Raul Marino Jr., Suely Kazuo Marie,

Paulo Henrique Aguiar, Manoel Jacobsen Teixeira

Departamento de Neurologia, Hospital das Clinicas, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, Brazil

Received 15 May 2005; received in revised form 30 July 2005; accepted 1 August 2005

Abstract

Objective: The objective of this paper is to evaluate factors of surgical morbidity from different techniques of hemispherectomy with

emphasis on causative pathology. Patients and methods: Thirty patients underwent hemispherectomy in our institution from 1987 to 2003,

two presented with Sturge–Weber Syndrome (SWS), sixteen with Rasmussen’s Syndrome (RS), eight with established hemispheric lesions

(EHL), and four with cortical development malformations (CDM). Six surgeons operated on three patients using anatomical

hemispherectomies (AH), 11 patients using functional hemispherectomy (FH), and 16 patients employing hemispherotomy (HT). Surgical

technique and causative pathology were studied independently as factors of morbidity in hemispherectomy. Results: Overall mean surgical

time was 11:50G3:20 h and increased proportionately in pathologies with larger hemispheres. Blood transfusion was particularly influenced

by the approach adopted by our team of anesthesiologists, independently of technique or pathology. Pathology was the most important factor

related to hydrocephalus as two out of four patients with CDM needed ventriculoperitoneal shunt whilst none with EHL or SWS. Four

patients undergoing HT and one FH presented residual bridges connecting the hemispheres, three were reoperated and are seizure free. Two

patients with CDM did not improve their seizures worthwhile with surgery and other two (one with RS and other with CDM) were waiting a

second procedure due to incomplete inter-hemispheric disconnection. Five patients presented infection and one died after developing

meningoencephalitis. Conclusion: Hemispherectomies are procedures where pathology and surgical technique interact narrowly. Therefore,

in order to study surgical morbidity or outcome, both pathology and technique have to be analyzed independently.

q 2005 Elsevier B.V. All rights reserved.

Keywords: Hemispherectomy; Hemidecortication; Hemispherotomy; Functional hemispherectomy; Epilepsia; Neurosurgery; Morbidity

1. Introduction

Anatomical hemispherectomy (AH) has been used in

treating seizure since the 1930s. However, it was almost

abandoned in the 1960s after reports of postoperative

fatalities caused by hydrocephalus, hemosiderosis, and

trivial head traumas [1]. Despite serious complications,

patients’ remarkable improvement encouraged surgeons to

0387-7604/$ - see front matter q 2005 Elsevier B.V. All rights reserved.

doi:10.1016/j.braindev.2005.08.005

* Corresponding author. Address: Instituto Neurologico de Sao Paulo,

Rua Maestro Cardim, 808Liberdade, Sao Paulo, SP CEP 01323-001, Brazil.

Tel.: C55 11 9659 2857/3141 9550; fax: C55 11 3141 9556.

E-mail address: [email protected] (A.N. Almeida).

modify the AH in order to lessen its morbidity whilst

preserving efficacy. Efforts to improve the technique gave

rise to several unique procedures, which remain in use to

this day.

Given that all approaches are able to achieve complete

isolation of the damaged hemisphere, sufficient to render the

patient free of seizures [2], the rationale behind choosing a

particular technique should be based on its related

morbidity. Unfortunately, comparing the morbidity of

different techniques drawing from the literature is not

straightforward. Some authors describe blood loss, operat-

ive time, and risk of developing either hydrocephalus or

hemosiderosis, as drawback parameters related specifically

to the technique [3,4]. However, it would be reasonable to

assume that other factors, such as the causative pathology,

Brain & Development 28 (2006) 215–222

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A.N. Almeida et al. / Brain & Development 28 (2006) 215–222216

also bias these parameters. Furthermore, most papers give

an account of a series of cases operated on by the same

individual and as a consequence the experience and ability

of the surgeon in question are bound to have a considerable

influence on results.

In the literature, pathology is already considered the

main determinant for seizure control, where its importance

for intra and postoperative course has been cited but as yet

not fully addressed. The objective of this paper is to evaluate

the surgical morbidity of different techniques of hemi-

spherectomy with emphasis on pathology as a distinct

morbidity factor.

2. Patients and methods

Thirty patients underwent hemispherectomy in our

institution from 1987 to 2003, these being fourteen females

and sixteen males with an average age of 11.5G8.9 years,

ranging from 7 months to 38 years. Pre-operative work up

included a thorough history of the disease, video-EEG with

seizure recordings, neuropsychological evaluation, CT scan,

and MRI. The Wada test was used only when language

lateralization was uncertain. A multidisciplinary group

analyzed the data before a final agreement on surgery was

reached.

In this series, two patients presented with Sturge–Weber

Syndrome (SWS), sixteen with Rasmussen’s Syndrome

(RS), eight with established hemispheric lesions, sequelae

of previous vascular or traumatic event, with or without

porencephalic cyst (EHL), and four with cortical develop-

ment malformations (CDM) (three with hemimegalence-

phaly and one with hemispheric cortical dysplasia).

In order to analyze our data and compare our results to

the literature, hemispherectomy techniques currently in use

were allocated to one of two main groups. Group 1 included

those techniques that completely remove the cortex from the

hemisphere, whilst Group 2 comprised those associated to

partial cortical removal and fiber disconnection. Group 1

presented two sub-divisions based on ventricular integrity

where Group 1A included techniques that involve opening

the lateral ventricles (called anatomical or classical

hemispherectomy) and Group 1B those that kept them

closed (called hemidecortication or hemicorticectomy).

Group 2 was sub-divided into three: functional hemispher-

ectomy (FH), as described by Rasmussen (Group 2A),

techniques that disconnect the hemisphere from a vertical

approach (Group 2B), and techniques disconnecting the

hemisphere from a lateral approach (Group 2C). In the

literature techniques included in the groups 2B and 2C are

frequently known as hemispherotomy. Fig. 1 shows

schematic drawings of techniques included within each

group.

Six surgeons operated on thirty patients. Three patients

underwent anatomical hemispherectomies (Group 1A), 11

patients underwent the functional hemispherectomy (Group

2A) and 16 were operated on employing three different

techniques from the lateral approach group (Group 2C).

Surgical time (from skin incision to skin closure), blood

transfusion, hydrocephalus, postoperative seizures, infec-

tion, and mortality/unexpected-neurological-deficits were

reviewed as parameters of morbidity. At least three samples

of peripheral blood were examined for each patient, one

preoperatively, one within 12 h following surgery, and

another on the third postoperative day.

2.1. Statistical analysis

Mean values and standard deviation were obtained from

all analyzed data. The two groups with different leukocyte

counts were compared using the Mann–Whitney test,

whereas the c2 test was employed to compare groups with

diverse surgical times and diverse volumes of blood

transfusion. Statistical significance was considered present

for P!0.05.

3. Results

3.1. Surgical time

Overall mean surgical time was 11:50G3:20 h, varying

from 6:30 to 19:00 h. Comparing different pathologies,

surgical time increased proportionately with larger hemi-

spheres though figures were not statistically significant.

Hemispherectomies on patients with CDM took on average

13:30 h, while on patients with RS or SWS the time stood at

12:00 h on average, whilst patients with EHL took 11:30 h.

The technique employed did not affect procedure length.

3.2. Blood transfusion

All but one patient in this series received a blood

transfusion during surgery. On average, each patient

received 3.3G1.4 units of packed red blood cells. Despite

transfusion, hemoglobin levels fell 1.0G1.4 g/dl, compar-

ing pre and immediate postoperative values. Hemoglobin

values on immediate postoperative hemogram averaged

12.5G1.5 g/dl. Over the first days after the procedure,

levels of hemoglobin continued to drop, by an average of

2.6G2.0 g/dl, and six patients had a second transfusion,

usually when their hemoglobin levels fell below 10 g/dl.

Hemoglobin reached its lowest values between the second

and the fifth postoperative day. There were no statistical

differences among groups of pathologies, or surgical

techniques in relation to blood transfusion requirement.

Ten patients developed leukocyte counts of over 20,000

cells per mm3 on the blood sample collected within 12 h

after surgery. This group evolved with an average decline in

hemoglobin of 3.8G1.7 g/dl over the proceeding day. In

contrast, patients with leukocyte counts below 20,000 cells

per mm3 presented an average decline of only 2.0G1.7 g/dl

Fig. 1. Schematic drawing of groups of hemispherectomy techniques: Group 1 includes techniques based on complete cortical removal and is divided in two

subgroups: 1A (intra ventricular approach) and 1B (extra ventricular approach). Group 2 assembles disconnective techniques and is divided in three subgroups:

2A (functional hemispherectomy), 2B (vertical approach), and 2C (lateral approach). The drawings were based on previously reported techniques that are

described in details in the original papers [3,9,25,27,29].

A.N. Almeida et al. / Brain & Development 28 (2006) 215–222 217


in hemoglobin (P!0.01). Variations in early postoperative

leukocyte counts were not linked to causative pathology,

technique, intra-operative blood transfusion, or surgical

length.

Data from each patient regarding surgical time, age,

hemoglobin variation, and the first postoperative white

blood count, separated by pathology and surgical technique

are shown on Tables 1 and 2.

3.3. Hydrocephalus

Three patients developed hydrocephalus three, four, and

six months respectively, after the hemispherectomy, and

underwent ventriculoperitoneal shunts, one with RS and two

with CDM. Two had undergone procedures from Group 2C

and one from Group 1A.

3.3.1. Postoperative Seizures

After surgery, MRI detected a residual bridge in the

corpus callosum connecting the hemispheres in five patients

(four with RS and one with CDM, four had undergone FH,

Table 1

Patient’s data separated by causative pathology

ID Path. Tech. Age Surg. time HB1 H

1 CDM 2C 2.2 17:00 15.8 12

2 CDM 2A 13 12:30 15.2 13

3 CDM 2C 1.7 18:00 14.9 14

4 CDM 1A 0.6 6:30 13.4 14

5 EHL 2C 16 9:00 14.7 12

6 EHL 2C 19 13:00 14.2 12

7 EHL 2C 7 12:00 11.3 13

8 EHL 2C 33 10:30 16.6 11

9 EHL 2C 16 12:30 11.6 10

10 EHL 2C 8 13:30 13.3 10

11 EHL 2C 18 11:30 14.2 12

12 EHL 2C 38 9:30 15.4 14

13 RS 2A 15 11:00 13.9 14

14 RS 2C 11 14:00 12.4 11

15 RS 2C 3 19:30 13.6 12

16 RS 2C 7 15:30 12.2 12

17 RS 2A 8 8:00 12.9 11

18 RS 2A 14 8:50 15 13

19 RS 1A 21 9:00 15.5 14

20 RS 2A 4.5 13:00 12.9 12

21 RS 2A 13.5 14:00 14 13

22 RS 2C 16 15:30 13.5 13

23 RS 2C 7 15:00 12.4 13

24 RS 2A 6.5 13:00 13.5 12

25 RS 2A 5.2 8:30 12.8 13

26 RS 2A 5.5 8:15 12.5 11

27 RS 2A 8 10:30 11.5 10

28 RS 2A 21 8:00 14.5 12

29 SWS 2C 4.5 8:00 13.1 11

30 SWS 1A 0.7 8:00 10 7

Legends: ID (patient’s identification), Pathol. (causative pathology), Tech. (used

surgery in years), Surg. Time (surgical time from skin to skin), HB1 (preoperati

lowest postoperative value), HB1-HB2 (difference between preoperative and imme

and the lowest postoperative hemoglobin), BT (blood transfusion in units of pack

* Patients that receive a second blood transfusion. ** The patient received blood

Group 2A, and one HT, Group 2C). All these patients

developed postoperative seizures and, on closer investi-

gation, scalp EEG disclosed epileptic activity spreading

between the hemispheres. Three patients with RS underwent

a second operation to complete disconnection of the corpus

callosum and became seizure free thereafter. Intense

electrical activity was revealed by electrocorticography

over the insula in one of these patients where the area was

then removed during the operation. The other two patients

with incomplete disconnection are awaiting a second

procedure.

Twenty-one patients received follow-up over one year,

three over less than a year, whilst one deceased, and five

were lost during follow-up. A total of 17, out of 21, were

seizure free or had a 90%, or greater, improvement in their

seizures. Four patients remained with seizures, which

recurred few days after the surgery. Two of these were

awaiting a second procedure, made necessary due to

incomplete disconnection of the corpus callosum (one

with RS and other with CDM) and the remaining two did not

improve significantly with surgery (both had CDM).

B2 HB3 HB1-HB2 HB2-HB3 BT WBC

.1 9.7 3.7 2.4 2 15600

.6 9.6 1.6 4 3 21600

.5 8.6* 0.4 5.9 3.2 30000

.1 10.1 K0.7 4 3.5 14200

.1 11.7 2.6 0.4 3 12620

.8 9.6 1.4 3.2 2 37700

.3 8* K2 5.3 2 26300

.9 10.2 4.7 1.7 0 14370

.4 10.3 1.2 0.1 5 9800

.8 10.2 2.5 0.6 4 17830

.5 12 1.7 0.5 4 11760

10.8 1.4 3.2 1 22780

.7 9.7 K0.8 5 4 12100

.8 11.5 0.6 0.3 4 15200

.7 10.1 0.9 2.6 3 12130

.5 10 K0.3 2.5 4 13200

.9 10 1 1.9 3 10300

9.7 2 3.3 5 13300

8.1* 1.5 5.9 5 23900

.5 10.5 0.4 2 3 22100

.5 10.5 0.5 3 4 15800

.6 8.8* K0.1 4.8 5 22400

.2 9.9 K0.8 3.3 4 23000

.3 11.8 1.2 0.5 3 27600

.9 8.8* K1.1 5.1 2 11600

.9 11.7 0.6 0.2 3,3 16600

.5 10.2 1 0.2 4 12000

.5 7.8* 2 4.7 5 13400

.7 11.5 1.4 0.2 1 13590

.5** 12.1 2.5 0 2,9 14100

surgical technique, specified by groups reported on Fig. 1), Age (age at

ve hemoglobin), HB2 (first postoperative hemoglobin), HB3 (hemoglobin

diate postoperative hemoglobin), HB2-HB3 (difference between immediate

ed red blood cells), and WBC (first postoperative white blood cells count).

transfusion right after his arrival at ICU.

Table 2

Patient’s data separated by surgical technique

ID Tech. Path. Age Surg. time HB1 HB2 HB3 HB1-HB2 HB2-HB3 BT WBC

7 2C EHL 7 12:00 11.3 13.3 8* K2 5.3 2 26300

22 2C RS 16 15:30 13.5 13.6 8.8* K0.1 4.8 5 22400

5 2C EHL 16 9:00 14.7 12.1 11.7 2.6 0.4 3 12620

11 2C EHL 18 11:30 14.2 12.5 12 1.7 0.5 4 11760

14 2C RS 11 14:00 12.4 11.8 11.5 0.6 0.3 4 15200

8 2C EHL 33 10:30 16.6 11.9 10.2 4.7 1.7 0 14370

16 2C RS 7 15:30 12.2 12.5 10 K0.3 2.5 4 13200

23 2C RS 7 15:00 12.4 13.2 9.9 K0.8 3.3 4 23000

29 2C SWS 4.5 8:00 13.1 11.7 11.5 1.4 0.2 1 13590

15 2C RS 3 19:30 13.6 12.7 10.1 0.9 2.6 3 12130

12 2C EHL 38 9:30 15.4 14 10.8 1.4 3.2 1 22780

6 2C EHL 19 13:00 14.2 12.8 9.6 1.4 3.2 2 37700

3 2C CDM 1.7 18:00 14.9 14.5 8.6* 0.4 5.9 3,2 30000

1 2C CDM 2.2 17:00 15.8 12.1 9.7 3.7 2.4 2 15600

10 2C EHL 8 13:30 13.3 10.8 10.2 2.5 0.6 4 17830

9 2C EHL 16 12:30 11.6 10.4 10.3 1.2 0.1 5 9800

17 2A RS 8 8:00 12.9 11.9 10 1 1.9 3 10300

2 2A CDM 13 12:30 15.2 13.6 9.6 1.6 4 3 21600

20 2A RS 4.5 13:00 12.9 12.5 10.5 0.4 2 3 22100

24 2A RS 6.5 13:00 13.5 12.3 11.8 1.2 0.5 3 27600

26 2A RS 5.5 8:15 12.5 11.9 11.7 0.6 0.2 3,3 16600

13 2A RS 15 11:00 13.9 14.7 9.7 K0.8 5 4 12100

21 2A RS 13.5 14:00 14 13.5 10.5 0.5 3 4 15800

25 2A RS 5.2 8:30 12.8 13.9 8.8* K1.1 5.1 2 11600

18 2A RS 14 8:50 15 13 9.7 2 3.3 5 13300

27 2A RS 8 10:30 11.5 10.5 10.2 1 0.2 4 12000

28 2A RS 21 8:00 14.5 12.5 7.8* 2 4.7 5 13400

30 1A SWS 0.7 8:00 10 7.5** 12.1 2.5 0 2,9 14100

4 1A CDM 0.6 6:30 13.4 14.1 10.1 K0.7 4 3,5 14200

19 1A RS 21 9:00 15.5 14 8.1* 1.5 5.9 5 23900

See legend at Table 1.

Table 3

Surgical complications

ID Inc. Disc. VPS CSF fist. Inf.

1 C

3 C C

5 C Osteom.

12 C Mening.*

14 Mening.

15 C Mening.

16 C

17 C18 C

19 C

20 C

26 Skin Inf.

27 Skin Inf.

28 C

ID (patients’ identification as listed on table 1), Inc. Disc. (incomplete

disconnection), VPS (ventriculoperitoneal shunt), CSF fist. (CSF fistulae),

Inf (Infection), Skin inf (skin infection), Mening. (meninigitis), Osteom.

(osteomyelitis). *Patient deceased.


3.4. Infection

Seventeen patients presented at least one peak of axillary

temperature S38.5 8C. Ten patients underwent at least one

lumbar puncture to rule out CSF infection. There was no

pathogen growth on CSF but three patients presented

leukocyte counts on CSF of over 1000/mm3 and were

treated for meningitis with broad-spectrum antibiotics. One

of them deceased on the 27 postoperative day. He developed

an incisional fistula and the necropsy revealed meningoen-

cephalitis. Patients without bacterial meningitis averaged

109G136 leukocytes/mm3, 106G69.4 mg/dl of protein,

and 50G13.9 mg/dl of glucose in CSF.

Three other patients developed CSF fistula, two being

incisional and one nasal (two had RS and one EHL). Two

resolved with continuous lumbar drainage and antibiotics.

One developed osteomyelitis requiring bone flap removal,

where dura mater was patched during the procedure. Two

other patients developed skin infection, but were treated

with antibiotics only. Patients’ postoperative complications

are listed on Table 3.

3.5. Mortality/unexpected-neurological-deficits

There was no occurrence of unexpected neurological

deficit aggravation. Two patients with RS and one with

SWS had residual fine motricity in the affected hand before

surgery, which was lost after the procedure. No patient in

this series presented hemosiderosis or late-onset hydro-

cephalus. As mentioned before, one patient deceased after

developing postoperative menigoencephalitis.


4. Discussion

This series represents a unique combination of several

surgeons performing different hemispherectomy techniques

within the same institution. In such a context, differences

among techniques cannot be attributed to externally

acquired experience as all surgeons were at the same point

in their learning curves. Our results better reflect the reality

in groups having experience in epilepsy surgery but who are

not yet entirely familiar with hemisperectomy. The

parameters of surgical time, blood transfusion, hydrocepha-

lus, postoperative seizures, infection, and mortality/unex-

pected-neurological-deficits were chosen because they are

frequently used to justify development of new surgical

approaches.

Reduction in surgical time has been cited as an advantage

of the techniques from group 2. In our series the surgical

time did not differ appreciably amongst the different

techniques. Nevertheless, surgical procedures on patients

with CDM were approximately 20% longer than those on

patients with EHL, although these differences did not

translate to noticeable morbidities.

Bleeding is still a concern during hemispherectomies,

however, comparing data from different series is not

feasible as authors use different parameters to measure

blood loss. Kestle et al. [5] and Schramm et al. [6] reported

progressive reduction in blood loss or transfusion necessity

when comparing techniques from Group 1B, Group 2A and

Group 2C. Jonas et al. [7], on the other hand, reported

differences in blood loss among pathologies, being higher in

patients with hemimegalencephaly. In our series, 29 patients

received packed red cells intra-operatively. On average, the

amount transfused was higher than in other series but was

not linked to pathology or technique [6,8]. Our increased

blood volume may reflect higher intra-operative bleeding or,

lower tolerance threshold for postoperative anemia adopted

Table 4

Compilation of different series regarding the incidence of subacute hydrocephalu

RS CDM SWD EHL

1A 0/0 15/5 0/0 0/0

0/0 0/0 1/0 15/0

1/1 1/0 1/0 0/0

1/1 16/5 2/0 15/0

1B 27/5 24/10 2/1 4/0

27/5 24/10 2/1 4/0

2A 0/0 12/3 0/0 0/0

10/0 1/0 0/0 0/0

10/0 13/3 0/0 0/0

2B 15/0 20/10 6/0 12/0

15/0 20/10 6/0 12/0

2C 1/0 26/5 0/0 6/0

4/0 10/3 2/0 11/0

1/0 2/0 1/0 16/0

5/0 2/2 1/0 6/0

11/0 40/10 4/0 39/0

Total 64/5 113/38 14/1 70/0

The first figure refers to total of patients reported by the cited series and the seco

by our team of anesthesiologists. Most of our patients left

the operating theater with hemoglobin levels above 12 g/dl

and none presented hemodynamic instability during the

procedure. In the ICU, hemoglobin continued to drop for a

few days and six patients needed a second blood transfusion

when their hemoglobin levels fell below 10 mg/dl. Notably,

postoperative progressive anemia was not associated with

intra-operative blood loss, blood transfusion, technique,

pathology, or patient age. Initially, it was thought to be the

result of bleeding from the subgaleal drain. However, there

was a strong association between hemoglobin reduction and

leukocyte counts of over 20,000/mm3 in the earliest

postoperative hemogram. As fever and hemodynamic

abnormalities are frequent in the postoperative period, it is

reasonable to suppose that this fall in hemoglobin may be

related to some sort of systemic inflammatory response,

however, further studies are needed to clarify this. Thus, the

amount of blood loss during and after the surgery is

attributable to a combination of surgical technique,

pathology and inflammatory factors.

Hydrocephalus is a frequent morbidity following

hemispherectomies and may develop under two different

circumstances: either within months of the procedure, or

years later. Rasmussen believed subacute hydrocephalus

was a defect of CSF absorption secondary to the huge

removal of the subarachnoid space [9]. Late onset

hydrocephalus, for its part, has been attributed to either

superficial cerebral hemosiderosis or low-pressure hydro-

cephalus [10]. In our series however, the most important

factor associated to subacute hydrocephalus was pathology,

whereby 50% of our patients with CDM needed ventricu-

loperitoneal shunt. Compiling series from the literature

whose shunts were reported by surgical technique and

pathology, there is a clear preponderance of subacute

hydrocephalus in patients with CDM (Table 4). Since

patients with CDM have larger hemispheres, the higher

s separated by surgical technique and causative pathology

Total

Di Rocco and Iannelli (2000) [12]

Davies et al. (1993) [27]

Current series

34/6

Vining et al. (1997) [25]

57/16

Carreno et al. (2001) [28]

Current series

23/3

Delalande et al. (2001) [29]

53/10

Shimizu and Maehara (2000) [8]

Devlin et al. (2003) [26]

Schramm et al. (2001) [6]

Current series

94/10

261/44

nd number to total of ventriculoperitoneal shunts inserted.


incidence of hydrocephalus may be a consequence of debris

in the surgical cavity, which are more abundant after

operating on a thicker parenchyma. The series of Jonas et al.

[7] reported higher incidence of shunting in all groups of

pathologies although was not included in the table since a

proportion of his patients underwent ventriculoperitoneal

shunt routinely after hemispherectomy [11]. Therefore, it is

not feasible to ascertain the actual rate of hydrocephalus in

their series. Di Rocco and Iannelli [12] found correlation

between subacute hydrocephalus and patient age, yet not

technique. Our results may corroborate these findings to

some extent, as patients with CDM are usually considered

surgical candidates earlier than in other pathologies.

Papers published in the sixties considered superficial

cerebral hemosiderosis (SCH) as an inevitable and fatal

complication of hemispherectomy [13]. Despite the small

number of our patients who underwent anatomical

hemispherectomy (Group 1A), there were no instances of

late onset hydrocephalus or SCH in our series. In 1973,

Rasmussen [14] reported the MNI experiment with follow

up over thirty years, of patients with anatomical and subtotal

hemispherectomy. The author concluded that a small

portion of remnant brain would be sufficient to protect

against SCH. This may account to some extent for the lack

of such problem in the current literature, as more recent

series have used techniques that leave a portion of the brain

in the cavity. Although hydrocephalus and SCH may

manifest several decades after the procedure, it is the

exception, not the rule [15]. The average interval between

surgery and SCH has been described as 8 years [9]. As

Rasmussen’s technique was developed in the seventies, one

could expect several cases of SCH by now if the technique

were not protective against such a condition. On the other

hand, in patients who have undergone AH today (Group

1A), widespread use of CT scan may allow early diagnosis

and treatment for bleeding in the surgical cavity shown to be

effective in preventing the development of SCH [16].

Finally, Cook et al. [17] presented 34 patients who

underwent AH, in which ventriculoperitoneal shunt was

used almost routinely, with at least 14 years of follow up and

none presented SCH. Therefore, although SCH is still

related to AH (group 1A), it may not be considered a

common cause of morbidity today so long as patients

receive proper follow up.

Currently, causative pathology, not surgical technique, is

considered the main factor for postoperative seizure control

[18,19]. However, procedures other than from group 1A

may leave bridges between the hemispheres or epilepto-

genic areas over either the insula or the basal frontal lobe

that perpetuate seizures spreading [20,21]. Incomplete

disconnection occurred in 18.5% of our cases, the same

incidence as reported by Peacock et al., [11] in patients

operated on with functional hemispherectomy (Group 2A).

Shimizu and Maehara [8] reported this in 9% of his patients

using modified peirinsular hemispherotomy, while

Schramm et al., [6] reported none in their series (both

author employed techniques from Group 2C). Finally,

Kossoff et al. [18] reported five patients out of 111

reoperated upon after initial hemidecortication (group 1B)

due to persistent seizures and residual tissue identified on

MRI. Incomplete disconnection may happen using almost

all techniques, although it may be reduced according to

surgeons’ experience. Pathologies with thicker cortical

mantles, such as hemimegalencefalia, may increase the

chances of its occurrence. Therefore, incomplete disconnec-

tion should not be considered a complication but an

expected morbidity, at least, at the beginning of the

surgeon’s learning curve.

Considering operative mortality and major morbidity

together, hemispherectomy is still a risky procedure,

regardless of technique or pathology. Our series presented

a rate of postoperative fever similar to what is reported in

the literature. Temperature elevation after hemispherectomy

is a common phenomenon and has been attributed aseptic

meningitis. On the other hand, we had a high rate of

complications like infection and CSF fistulae. We credited

such drawback to the teaching characteristic of our

institution, where several in-training medical teams con-

tributed to surgeries. One patient deceased in our series due

to meningoencephalitis. Other authors have reported brain

stem lesion, excessive blood loss, brain swelling, general-

ized hypoxia, infection, locked-in syndrome, and shunt

failure as causes of death or permanent sequelae [6–8,

21–25]. The death rate reached up to 5.7% in recent series

and, even in a series without death or permanent sequelae,

life-threatening operative complications occurred in 10% of

cases [26].

5. Conclusions

Hemispherectomies are procedures where pathology and

surgical technique interact narrowly. In order to define

causes of morbidity both factors have to be analyzed

independently. From this standpoint, it is not possible to

infer that a specific technique of hemispherectomy has less

morbidity or better outcome if results are not adjusted for

different causative pathologies.

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Factors of morbidity in hemispherectomies: Surgical technique×pathology

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