Mutism as a consequence of callosotomy

Balloon-Assisted Corpus Callosotomy. Reducing the Impact of Transcallosal Approaches

BACKGROUND

The interhemispheric transcallosal approach is widely used to remove intraventricular lesions. Corpus callosotomy gives immediate access to the ventricular chambers but is invasive in nature. Loss of callosal fibers, although normally tolerate, may cause disturbances ranging from a classical disconnection syndrome up to minor neuropsychological changes.

OBJECTIVE

To open an operative window in the corpus callosum through separation rather than disconnection of the white matter fibers.

METHODS

In 7 patients undergoing the interhemispheric transcallosal approach for intraventricular lesions, lying around or below the foramen of Monro, a stoma was created within the corpus callosum by using a 4F Fogarty catheter. The series included 3 colloid of the third ventricle, 2 thalamic cavernomas, 1 subependymoma, and 1 ependymoma of the foramen of Monro. We illustrate the technique and the clinico-radiological outcome, focusing on the size of callosotomy as seen on postoperative MRI.

RESULTS

The balloon-assisted corpus callosotomy provided a circular, smooth-walled access to the ventricular chambers, which allowed uncomplicated removal of the lesions. On postoperative MRI, the size of the callosotomy shrinked compared with surgery (2.8-6.4 mm at follow-up vs 6-9 mm as measured intraoperatively). No signs of disconnection syndrome or new permanent deficits were observed in this series.

CONCLUSION

The balloon-assisted technique produces a small callosotomy, without clinical consequences, showing a self-closing trend on postoperative MRI. This technique is a rewarding tool to reduce the impact of callosotomy while keeping the advantages of microsurgical interhemispheric approaches.

Clinical prognosis of isolated anterior cerebral artery territory infarction: a retrospective study

Background

Isolated anterior cerebral artery territory (ACA) infarction is a rare phenomenon, and is known to have distinctive clinical features. Little is known regarding the clinical prognosis of isolated ACA territory infarction with associated factors, and its impact on dwelling and job status. We investigated the short- and long-term outcomes of anterior cerebral artery (ACA) territory infarction, and the associated factors involved in the development of the distinctive symptoms.

Methods

This retrospective study in a prospective cohort of acute ischaemic stroke patients included consecutively enrolled patients with isolated ACA territory infarction. We investigated the functional status using the modified Rankin scale (mRS) score at discharge, three months’ post-discharge, and one-year post-discharge. We also investigated the occlusion site of the ACA (proximal vs. distal); presence of distinctive symptoms of ACA territory infarction including behaviour changes, indifference, aphasia, and urinary incontinence; and the effect of these symptoms on dwelling and job status one year after discharge.

Results

Between April 2014 and March 2019, 47 patients with isolated ACA territory infarction were included. Twenty-nine patients (61.7 %) had good outcomes (mRS ≤ 2) at discharge; however, the mRS score increased at three months (40; 85.1 %, p < 0.001) and one year (41; 87.2 %) post-discharge. Occlusion of the ACA proximal segment was independently associated with the development of distinctive symptoms (adjusted odds ratio, 17.68; 95 % confidence interval: 2.55–122.56, p < 0.05). Twenty-one (48.8 %) patients with good outcomes at one year experienced a change in dwelling status and job loss; 20 (95.2 %) of them had distinctive ACA territory symptoms with proximal ACA occlusion.

Conclusions

Short- and long-term outcomes of isolated ACA territory infarction were favourable. However, proximal segment occlusion was associated with the development of distinctive symptoms, possibly related to future dwelling and job status.

Neurosurgical approaches to pediatric epilepsy: Indications, techniques, and outcomes of common surgical procedures

Epilepsy is a common pediatric neurological condition, and approximately one-third of children with epilepsy are refractory to medical management. For these children neurosurgery may be indicated, but operative success is dependent on complete delineation of the epileptogenic zone. In this review, surgical techniques for pediatric epilepsy are considered. First, potentially-curative operations are discussed and broadly divided into resections and disconnections. Then, two palliative approaches to seizure control are reviewed. Finally, future neurosurgical approaches to epilepsy are considered.

Clinical and MRI patterns of pericallosal artery infarctions: the significance of supplementary motor area lesions

Cerebral infarctions in the anterior cerebral artery (ACA) territory account for only up to 3-5% of strokes. Subject to the affected ACA branches, different clinical patterns can be defined. We report a case series of patients with isolated infarctions of the pericallosal (PC) artery territory. We analyzed 36 consecutive patients presenting over a 10-year period with isolated PC artery territory infarctions (15 left-sided, 19 right-sided, 2 bilateral) regarding clinical symptoms as well as MRI findings. Analysis of DWI lesion pattern showed complete PC artery infarctions in three patients. The majority of patients had partial infarctions predominantly involving either the superior frontal gyrus (n = 12), the corpus callosum (n = 1) or both (n = 20). Hemodynamic lesion patterns were found in 13 patients, while multiple cortical emboli occurred in six. Distal pathology of the ACA (n = 13) was the most frequent MRA finding. Core symptom was contralateral hemiparesis with lower limb predominance (n = 29), partly associated with early-onset spasticity. Interestingly, motor evoked potential recording was abnormal in only five patients. Further characteristic symptoms were psychomotor slowing (n = 9), often with speech disturbances such as decreased verbal fluency, and confusional state (n = 4). Visual or motor hemineglect (n = 5) as well as apraxia (n = 5) was confined to a few patients only. Pericallosal artery infarctions are a rare localization of stroke, mostly occurring as partial infarctions due to distal ACA pathology. Clinically, they are mainly characterized by hemiparesis predominately in the lower limb caused by involvement of supplementary motor cortex areas without affection of the corticospinal tract.

The anatomy of the callosomarginal artery: applications to microsurgery and endovascular surgery

BACKGROUND

The callosomarginal artery (CMA), the main branch of the pericallosal artery, courses in or near the cingulate sulcus and gives rises to 2 or more major cortical branches. There is confusion about the artery best fitting the definition of "callosomarginal artery." Distal anterior cerebral artery aneurysms represent 1.5% to 9% of intracranial aneurysms, and most often occur at the origin of the CMA. The microsurgical anatomic features of the CMA, its relationship with the pericallosal artery, and clinical implications are presented.

METHODS

The origin, course, branching pattern, and diameter of the CMA and its branches and its relationship with the pericallosal artery were studied in 60 cerebral hemispheres, including cadaveric dissections and angiographic images.

RESULTS

The CMA was present in 93.3% of hemispheres studied and arose mainly from A3 (55.2%), a mean of 3.11 +/- 1.90 cm from the anterior communicating artery. The mean diameter of the CMA at its origin was 1.53 +/- 0.36 mm. The CMA ran 1.28 +/- 0.89 cm until its first branch, describing an anterior convex curve backward and upward (60.7%). An average of 3 lesser branches originated from the CMA. The most consistent branch was the posterior internal frontal artery (67.9%). The mean diameter of the CMA branches was 0.93 +/- 0.33 mm.

CONCLUSION

These morphometric measurements can help neurosurgeons access lesions located in distal intracranial vessels. The vessel coursing the longest pathway in or near the cingulate sulcus and otherwise following Moscow's classic definition should be considered the CMA.

Altered oscillatory brain dynamics after repeated traumatic stress

BACKGROUND

Repeated traumatic experiences, e.g. torture and war, lead to functional and structural cerebral changes, which should be detectable in cortical dynamics. Abnormal slow waves produced within circumscribed brain regions during a resting state have been associated with lesioned neural circuitry in neurological disorders and more recently also in mental illness.

METHODS

Using magnetoencephalographic (MEG-based) source imaging, we mapped abnormal distributions of generators of slow waves in 97 survivors of torture and war with posttraumatic stress disorder (PTSD) in comparison to 97 controls.

RESULTS

PTSD patients showed elevated production of focally generated slow waves (1-4 Hz), particularly in left temporal brain regions, with peak activities in the region of the insula. Furthermore, differential slow wave activity in right frontal areas was found in PTSD patients compared to controls.

CONCLUSION

The insula, as a site of multimodal convergence, could play a key role in understanding the pathophysiology of PTSD, possibly accounting for what has been called posttraumatic alexithymia, i.e., reduced ability to identify, express and regulate emotional responses to reminders of traumatic events. Differences in activity in right frontal areas may indicate a dysfunctional PFC, which may lead to diminished extinction of conditioned fear and reduced inhibition of the amygdala.

Corpus callosotomy using conformal stereotactic radiosurgery

OBJECTS

To show the clinical results of a corpus callosotomy (CC) treatment using conformal stereotactic radiosurgery (SRS) on a patient with medically intractable multifocal epilepsy.

MATERIALS AND METHODS

A 17-year-old male patient underwent corpus callosotomy conformal SRS using a dedicated linear accelerator (linac) with dynamic arcs technique. The prescribed dose was 36.0 Gy at the periphery of the rostrum, genu, and a half of the body of the corpus callosum (CCA). At 8 months after conformal SRS, the patient developed a significant brain edema and moderate transitory motor deficit, which were controlled with steroids. After 32 months follow-up, there is an improvement of 84% on drop attacks and generalized tonic-clonic seizures.

CONCLUSIONS

Conformal SRS for corpus callosotomy with a single isocenter reproduce the results reported on literature using Gamma Knife-based SRS. The results show that this technique is safe and demonstrate its efficacy to control seizures.

Postoperative mutism after removal of an anterior falcine meningioma

Postoperative mutism is rare. We present a 65-year-old man who had transient mutism after resection of anterior falx meningioma. Mild left hemiparesis and palmomental reflex on the right were the only abnormal signs on neurological examination. CT scan and MRI demonstrated a mass at the anterior one-third portion of the falx just superior to the corpus callosum. The mass enhanced homogenously with administration of gadolinium DTPA. The patient underwent surgical resection of the lesion and adjacent falx cerebri. The operation was uneventful. On the second postoperative day he became mute. He could follow verbal commands, and write and read. Postoperative CT scan revealed a hypodense area in the right frontal lobe including a part of the anterior cingulate cortex and the anterior part of the corpus callosum. Histopathological examination revealed a mixed meningioma. Ten days postoperatively, he began to say simple words, and three weeks later he could talk normally. We consider that lesion of the supplementary motor area (SMA) may be responsible for postoperative mutism.

Gamma knife radiosurgery for callosotomy in children with drug-resistant epilepsy

OBJECTIVES

Gamma knife radiosurgery as a noninvasive procedure is increasingly used as a treatment option in patients with intractable seizures. We investigated efficacy and safety of gamma knife radiosurgery (GKRS) for callosotomy in children.

MATERIALS AND METHODS

Between 2000 and 2004 three children between 4 and 14 years (mean 8 years) underwent radiosurgical callosotomy. One child presented with Lennox-Gastaut syndrome, two with hemispheric cortical dysplasia. These two children underwent functional hemispherotomy before GKRS. GKRS was performed with a marginal dose of 55-60 Gy on the 50% isodose.

RESULTS

Mean follow-up was 35 months. Radiosurgical callosotomy was ineffective in one child with the Lennox-Gastaut syndrome, whereas in the remaining two children, a 100% seizure reduction of generalized tonic-clonic seizures, 20-70% reduction of partial seizures, and a progress in mental and physical development was achieved. No postradiosurgical side effects were observed in all children.

CONCLUSION

Radiosurgical callosotomy might be offered after hemispherotomy to complete callosal resection. However, larger number of patients and longer follow-ups are needed to draw final conclusions.

Corpus callosotomy in children

INTRODUCTION

For children of medical resistant epilepsy without resectable epileptogenic zone, corpus callosotomy and vagus nerve stimulation (VNS) therapy are the two commonly used palliative epilepsy surgeries that can be considered. Although their routes and mechanisms to control epilepsy are different, both surgeries have shown their efficacy in selected candidates. The most common candidates for palliative surgery are in infants and children with organic encephalopathic types of epilepsy including infantile spasms/West syndrome, Lennox-Gastaut syndrome (LGS), severe epilepsy with multiple independent spike foci (SE-MISF) and selected symptomatic partial epilepsy to relief seizures and to stabilize co morbidities (Hirsch and Arzimanoglou, Revue Neurologique [Hirsch E and Arzimanoglou A, Rev Neurol (Paris). 160 Spec No 1:5S210-S219, (2004); Ohtahara S and Yamatogi Y, J Clin Neurophysiol 20(6):398-407, (2003); Wheless JW and Epilepsia 45(Suppl 5):17-22, (2004); Trevathan E, J Child Neurol 17 Suppl 2:2S9-2S22, (2002)].

DISCUSSION

Callosotomy is a major and destructive but affordable surgical procedure as compare to the relative simple but costly extracranial procedure of VNS therapy. However, callosotomy is a safe and effective palliative operation in neurosurgeons familiar with the surgical procedure. Equipments for callosotomy can be as simple as headlight and binocular loupes, self-retention brain retractor, bipolar cauterization, and simple microinstruments.

Efficacy and Safety of Radiosurgical Callosotomy: A Retrospective Analysis

PURPOSE

Anterior callosotomy is a surgical option for the treatment of generalized tonic or atonic seizures associated with drop attacks. Besides open surgery, a radiosurgical callosal disconnection using the gamma knife (GK) also can be performed, but reliable data about tolerability and efficacy are sparse.

METHODS

Eight patients (three female, five male age range, 5 to 69 years) with severe generalized epilepsy associated with disabling drop attacks underwent GK callosotomy between 1993 and 2004. In six patients, the anterior third of the corpus callosum was radiosurgically disconnected. In one patient a second procedure with GK treatment of the middle third of the corpus callosum was added 17 months later. In two patients posterior GK callosotomy had followed partial hemispherotomy.

RESULTS

Drop attacks (DAs) were completely abolished in three patients, and two patients had a marked DA seizure reduction of 60%. Two of four patients with additional generalized tonic-clonic seizures showed a reduction of 100%, and the remaining, a 50% and 60% decrease, respectively. Other seizure types responded less well to the radiosurgical treatment. In both patients with posterior GK callosotomy after hemispherotomy, partial seizures decreased. Beside transient headache in two patients, no immediate or long-term postradiosurgical side effects were observed.

CONCLUSIONS

Palliative radiosurgical callosotomy is an efficient and safe noninvasive alternative to the open procedure with comparable results. No signs of postradiosurgical side effects were noted within an up to 12-year posttreatment period.

Refractory generalized seizures: response to corpus callosotomy and vagal nerve stimulation

PURPOSE

The vagal nerve stimulator (VNS) and corpus callosotomy can reduce seizure frequency when seizures are refractory to medications. However, the efficacy and safety of these two procedures have not been compared. This study evaluates the two procedures for generalized seizures.

METHODS

All patients with refractory generalized seizures (generalized tonic-clonic, tonic, or atonic) who underwent a corpus callosotomy (anterior or complete) (n = 53) without other forms of epilepsy surgery and those who underwent VNS placement (n = 25) were evaluated for this study. Seizure response and procedure complications were evaluated.

RESULTS

For those with a corpus callosotomy and generalized tonic-clonic seizures (n = 50), 79.5% had >or=50% decrease in the frequency of generalized tonic-clonic seizures, and 60% had >or=80% seizure reduction. For those with a VNS and generalized tonic-clonic seizures (n = 21), 50% had >or=50% seizure reduction, and 33% had >or=80% seizure reduction. Tonic and atonic seizures decreased after either VNS or a corpus callosotomy. The complication rate for corpus callosotomy was higher (21% all complications, 3.8% permanent) than that for VNS (8%; none permanent), but complications for both corpus callosotomy and VNS were rarely permanent.

CONCLUSIONS

Both corpus callosotomy and VNS are effective in reducing generalized seizures. Corpus callosotomy is associated with greater efficacy but higher risk for complications, although these were generally transient.

Spectrum of anterior cerebral artery territory infarction: clinical and MRI findings

To evaluate and review the clinical spectrum of anterior cerebral artery (ACA) territory infarction, we studied 48 consecutive patients who admitted to our stroke unit over a 6-year period. We performed magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) in all patients, and diffusion magnetic resonance imaging (DWI) in 21. In our stroke registry, patients with ACA infarction represented 1.3% of 3705 patients with ischemic stroke. The main risk factors of ACA infarcts was hypertension in 58% of patients, diabetes mellitus in 29%, hypercholesterolemia in 25%, cigarette smoking in 19%, atrial fibrillation in 19%, and myocardial infarct in 6%. Presumed causes of ACA infarct were large-artery disease and cardioembolism in 13 patients each, small-artery disease (SAD) in the territory of Heubner's artery in two and atherosclerosis of large-arteries (<50% stenosis) in 16. On clinico-radiologic analysis there were three main clinical patterns depending on lesion side; left-side infarction (30 patients) consisting of mutism, transcortical motor aphasia, and hemiparesis with lower limb predominance; right side infarction (16 patients) accompanied by acute confusional state, motor hemineglect and hemiparesis; bilateral infarction (two patients) presented with akinetic mutism, severe sphincter dysfunction, and dependent functional outcome. Our findings suggest that clinical and etiologic spectrum of ACA infarction may present similar features as that of middle cerebral artery infarction, but frontal dysfunctions and callosal syndromes can help to make a clinical differential diagnosis. Moreover, at the early phase of stroke, DWI is useful imaging method to locate and delineate the boundary of lesion in the territory of ACA.

Corpus callosotomy in Colombia and some reflections on care and research among the poor in developing countries

The authors present the results of a series of corpus callosotomies (CCS) in 97 patients performed from 1989 to 1997 at the Hospital Neurologico of the Liga Colombiana Contra La Epilepsia, Cartagena, Colombia. This study demonstrates the feasibility of performing these procedures in the developing world and analyzes the outcome and cost of treatment. Patients with medically intractable secondarily generalized epilepsy, bilateral nonfocal epileptic electroencephalogram (EEG), and absence of progressive encephalopathy were accepted as candidates (patients aged 0-30 years; 62 children, 19 girls and 43 boys, with mean age at surgery of 7.9 years; 35 adults, 19 women and 16 men, with mean age at surgery of 25.8 years). Preoperatively, the mean seizure frequency was 12.1 per day, or 364 per month (range, 0.06-200 per day, 1.8-6000 per month). Before surgery, 40% of patients were classified with generalized tonic-clonic seizures of different etiologies, or cryptogenic seizures; 36% had mixed seizures; 19% had Lennox-Gastaut Syndrome; and 5% had West Syndrome. Usually, routine EEG, computed tomography, and clinical findings sufficed for the surgical decision. The standard microsurgical technique performed was an anterior two-thirds CCS by the same surgeon under general anesthesia. In five cases, an additional frontal lobe excision after electrocorticography and subdural electrode monitoring was carried out in the same session. The results were evaluated after a mean follow-up of 35 months (range, 12-28). Two thirds of patients became seizure-free or were left with none or some disabling seizures. AED medication was eased slightly after surgery. The complication rate was low. The patients underwent postoperative psychosocial studies and neuropsychological rehabilitation and showed tendencies toward improvement. The direct cost of CCS in U.S. dollars (US$) ranged between 3,137 and 3,995 depending on the preoperative studies. Thus, CCS is well suited for selected patients in developing countries. Thus far, implantation of a vagus nerve stimulator has exceeded our economic possibilities in treating similar patients. Some reflections on care and research among epilepsy patients in developing countries are discussed.

Corpus callosotomy: seizure and psychosocial outcome. A 39-month follow-up of 20 patients

The aim of the present study was to investigate the effect of corpus callosotomy on seizures, with emphasis on the psychosocial outcome. Data were retrospectively obtained from 20 patients (mean age 20.8 years, range 6-46). Sixteen of the operated patients took part in the 39-month (range 19-62) follow-up. Outcome measures were post-operative seizures, changes in the antiepileptic drug treatment, surgical complications including disconnection syndrome, degree of dependency according to the Barthel index, quality of life, burden on caretakers and satisfaction with the treatment. Half of the patients had a favorable seizure outcome, and of these 50% noticed an improved quality of life and were satisfied with the treatment. Four patients suffered from symptoms of cerebral disconnection syndrome which interfered with the activities of daily life. One patient died of complications 3 months after the operation. There were no significant changes in antiepileptic drug treatment, the patients' social lives or the burden of the patients on the caretakers. The conclusion is that prospective studies are needed to clarify the criteria for optimal patient selection to increase the likelihood of a positive psychosocial outcome.

Clinical effects of longitudinal division of the corpus callosum in normal dogs

Longitudinal division of the corpus callosum was performed in six normal beagles to determine surgical morbidity. The corpus callosum was divided sagittally on the midline and the effect on neurological function was determined. Five of six dogs were clinically normal within 14 days or less after surgery. One dog had persistent but improving clinical signs consistent with a forebrain disturbance at 30 days after surgery. Overall, minimal morbidity and no mortality was associated with this surgical procedure. Further study is indicated to determine the efficacy of this surgical treatment for seizure control in dogs with idiopathic epilepsy.

Stereotactically guided transfrontal removal of intraventricular midline tumors in children. Neurosurgical and neuropsychological considerations

Five children with supratentorial intraventricular midline cerebral tumors were operated on using a stereotactically guided transfrontal approach. Assisted by a three-dimensional graphic reconstruction of cerebral anatomy, the surgeon was able to reach and remove the lesion with minimal damage to healthy parenchyma. Neurosurgical and neuropsychological evaluation of the results suggests that this surgical approach is a valid alternative to the transcallosal route. This image-based intraoperative guidance is as effective as landmark-oriented surgery, which requires section of the corpus callosum, possibly leading to neuropsychological deficits, particularly in the pediatric age group.

Postoperative mutism in neurosurgery. Report of two cases

Mutism is defined as a state in which a patient is conscious but unwilling or unable to speak. It has been reported to occur in association with a multitude of conditions, including trauma, epilepsy, tumors, stroke, psychoses, and brain surgery. The cases of two patients who became mute in the immediate postoperative period are presented. The first patient developed mutism following removal of a parasagittal meningioma, and the second following removal of a posterior fossa medulloblastoma. It is believed that transient injury may have occurred to the supplementary motor cortex in the first case and to the dentate nuclei in the second case. It is interesting that these two areas are connected via pathways involving the ventrolateral nucleus of the thalamus, and that lesions of this thalamic nucleus can also lead to mutism. It therefore appears plausible that interruption of these pathways may be involved in the pathogenesis of mutism. Although mutism is an infrequent complication of brain surgery, neurosurgeons should be aware that it may occur following removal of lesions in these areas and that it is generally a transient condition.

Crossed aphasia. An update

The aim of this article is to present an update of a rare but interesting problem: "crossed aphasia". This term indicates the presence of aphasia after unilateral cerebral lesion of the hemisphere ipsilateral to the patient's dominant hand. We report two cases, review the most relevant literature, and analyze clinical, neuroanatomical, and neurophysiological aspects, taking in consideration the various interpretations proposed to explain this unusual language disorder.

Atypical meningioma of the third ventricle in a 6-year-old boy

Pediatric meningiomas are uncommon. Those presenting in the third ventricle are rare; there are only 15 cases reported in the literature. We report an additional third ventricular meningioma in a 6-year-old boy. The tumor was resected via an anterior transcallosal interfornicial approach. Postoperatively, the patient exhibited a transient episode of mutism. Unlike previous reports, the pathological diagnosis of this lesion was an atypical meningioma. The presentation, management, pathological features, and postoperative course of our case are discussed and compared with previous reports.

Development of akinetic mutism and hyperphagia after left thalamic and right hypothalamic lesions

A case of childhood post-traumatic akinetic mutism is presented. The patient showed a hyperphagic condition while recovering from akinetic mutism. He had lesions in the left interlaminal nucleus of the thalamus, right globus pallidus, and right dorsomedial nucleus of the hypothalamus. Laboratory data indicated slightly disturbed hypothalamic functions. In general, akinetic mutism can be seen with bilateral destructive lesions, while hyperphagia may occur after destruction of dorsomedial hypothalamic nucleus, but it is very rare. This is the first reported case of akinetic mutism caused by a unilateral lesion.

Information processing in the separated hemispheres of callosotomy patients: does the analytic-holistic dichotomy hold?

The characterization of the left and right cerebral hemispheres as analytic and holistic, respectively, was evaluated with callosotomy patients. This distinction was operationalized by reference to the work of Garner, Kemler Nelson, and their colleagues on separable (analytic) and integral (holistic) dimensions of cognition. In one experiment, patients were asked to make similarity judgments when faced with triads of stimuli such that one pair matched on a criterial attribute (analytic) and another pair showed a family resemblance (holistic). The right hemisphere showed a stronger bias to judge on the basis of the criterial attribute. In a second experiment, each hemisphere was engaged separately in a concept formation task. Depending on the exemplars in a particular set, analytic or holistic processing was seen in either hemisphere. However, the left hemisphere was more likely to engage in analytic processing. The results suggest that both hemispheres are capable of either type of processing and may use either mode, depending on the nature of the task and stimulus material. Thus, the analytic/holistic distinction may not provide a simple, generalizable description of information processing differences between the two hemispheres.

The transcallosal approach for lesions affecting the lateral and third ventricles. Surgical considerations and results in a series of 42 cases

The study was carried out on a series of 42 patients who underwent surgery through a midline approach. Lesions were in the anterior part of the third ventricle in 32 cases, in the frontal horns in 6, in the trigone in 3, and in both lateral and third ventricles in 1 case. The third ventricle was approached through Monro's foramen in 22 cases and through an interfornicial route in 9 cases. Surgical mortality occurred in 2 cases (5%). Permanent morbidity occurred in another 2 cases (5%): it consisted of slight intellectual deterioration in one case and slight fixed pyramidal signs in the other. Transient mutism was the most frequently observed postoperative complication. Thirty-one patients were reviewed and submitted to neuropsychological tests in the late postoperative period to investigate the presence of intellectual deterioration or disturbances in the interhemispheric transfer of motor, somataesthetic and visual information. All patients showed only the presence of short-term memory disturbance. Furthermore, 12 patients tested before surgery also showed the presence of short-term memory deficits in the preoperative period. We conclude that a midline approach is the most direct and safe route to the third ventricle as well as to the frontal horns and trigone.

Mechanism of mutism following the transcallosal approach to the ventricles

Transient mutism has been known as a common manifestation following callosotomy for medically intractable epilepsy, but its cause has not been clearly elucidated. In this paper, we report three cases of mutism following a transcallosal approach to tumours in the lateral and third ventricles and retrospectively analyze the surgical, neurological and radiological features which may suggest the cause of this type of mutism. Mutism may be a result of division of the corpus callosum. Suppression of the limbic system caused by lesions in the anterior cingulate gyrus, septum pellucidum, and fornix may have been of importance in at least two of these three cases. Impairments of the supplementary motor cortex, thalamus and basal ganglia may also be factors reducing speech production. The mechanism of such transient mutism seems to be a complex of two or more of these factors, and their combinations may be different from one case to the other.

Biopercular lesions and acquired mutism in a young patient

A 13-year-old patient developed complete mutism and buccofacial apraxia following toxic vasculitis due to a yellow scorpion sting. Language functions were preserved. A CT scan disclosed mainly biopercular infarcts. It is suggested that the lost control of vocalization and speech is associated with biopercular lesions and that a preserved right opercular region can take over this function in the presence of damage to homologous left opercular region.

Advantages and disadvantages of the transcallosal approach to the III ventricle

The advantages of the transcallosal approach used in children during 10 years at the Department of Pediatric Neurosurgery in Prague are: strict midline approach to the III ventricle, sparing both fornices; convenient approach to the left lateral ventricle from a right sided craniotomy. The disadvantages are: neurological sequelae, the most serious of which are mutism and disturbances of recent memory. Older children and those who showed preoperative symptoms of the disconnection syndrome exhibited more deficits after callosotomy.

Evolution of neuropsychological changes after partial callosotomy in intractable epilepsy

Early neuropsychological changes following partial anterior callosotomy were evaluated in 15 patients with epilepsy (10 secondary generalized and 5 Lennox-Gastaut syndromes) by comparing their performances 1 month before surgery and then 15-20 and 90-100 days postoperatively without modifying the anticonvulsant treatment. The following neuropsychological and motor functions were tested: memory, attention, visuo-motor ability, posture, motor dexterity, language, praxis and gnosis. Social behaviour was also investigated. The main results are as follows: (i) most cognitive functions showed no significant variation; (ii) motor organization was still slightly impaired at the second check-up after the surgery; (iii) improvements in social behaviour and posture were frequently observed at the final evaluation. The analysis of individual cases highlights the influence of the extent of commissurotomy, lesions related to the surgical procedure and preoperative brain damage in determining the post-surgical profile. On this basis, the short-term neuropsychological cost of partial callosotomy appears to be low and seems to depend mostly on surgical parameters and brain conditions before the operation.

Postcallosotomy language impairments in patients with crossed cerebral dominance

Language impairments were reviewed retrospectively in patients who underwent partial or total corpus callosum section for medically refractory secondary generalized epilepsy. Postoperatively, four of 32 patients had clinically significant language impairments that were not present prior to the operation. All involved primarily verbal output (speech and writing) and spared verbal comprehension. Written language skills (reading and spelling), verbal memory, and verbal reasoning abilities were impaired to varying degrees. These impairments were associated with crossed cerebral dominance. Three patients with severe difficulties after surgery were right hemisphere-dominant for speech and were right-handed. One left hemisphere speech-dominant, left-handed patient was agraphic after surgery, but spoke normally. It is concluded from these data and from other reports in the literature that three syndromes of language disturbance may follow callosotomy. The first, involving speech difficulty but but sparing writing, is attributable to buccofacial apraxia. The second involves speech and writing difficulties and occurs in right hemisphere-dominant right-handed patients. The third involves dysgraphia with intact speech and occurs in left hemisphere-dominant left-handed patients.

Neuropsychological assessment of the transcallosal approach

The long-term consequences of partial callosal lesions were examined in 7 neurosurgically treated patients. Detailed clinical and neuropsychological assessment of the interhemispheric transfer (multimodal sensory and motor tasks) as well as memory and attention tests were used. The results revealed some disconnection symptoms with minor clinical significance, which could not be attributed to particular sites of the corpus callosum, except the splenium. It is questionable whether the reported memory and attention impairments are caused by the callosal lesion or by extracallosal pathology. The results indicate that the transcallosal approach is a safe and feasible alternative in the management of pathological midline processes in the brain.

Corpus callosotomy in the treatment of secondary generalizing intractable epilepsy

Over the past 5 years 9 patients underwent partial or complete corpus callosotomy for treatment of medically intractable epileptic seizures. A beneficial effect of the procedure was observed in 8 patients. Criteria for performance of the procedure included CT evidence of unilateral cerebral damage and non-localized epileptic foci in that hemisphere with secondary spread to the uninvolved side. The best results were obtained in atonic seizures. Long-term side effects were minor. The procedure is recommended in those patients with medically uncontrolled atonic or secondary generalized motor seizures in whom the corpus callosum is thought to mediate the spread of epileptic activity from a damaged cerebral hemisphere. Side effects are minimized by staging of the callosal section. If a partial callosotomy was beneficial, complete section can then be avoided.

CT-stereotaxic drainage of colloid cysts in the foramen of Monro and the third ventricle

Colloid cysts in the foramen of Monro and third ventricle account for 0.5% to 1% of all intracranial space-occupying lesions. The introduction of computerized tomography (CT) and magnetic resonance imaging has represented a major advance in the early detection of these cysts. The risks associated with the management of benign space-occupying lesions by open surgical procedures have made it necessary to search for safer techniques. The CT-stereotaxic method provides a simple, precise, and safe method of puncturing deep-seated space-occupying cysts. Between January, 1979, and December, 1984, 12 patients with colloid cysts in the foramen of Monro and third ventricle were operated on by this method. The operations were successful, and there were no intraoperative or postoperative complications. The advantages of the CT-stereotaxic method are discussed and the results are presented.