Lipoma of the insula. Case report

Sylvian fissure lipoma associated with fusiform aneurysm in the middle cerebral artery trifurcation: A case report and literature review

BACKGROUND

The intracranial lipomas are rare congenital malformations accounting for approximately 0.1-1.3% of all intracranial tumors, of which Sylvian fissure lipomas account for <5%. These lesions are frequently associated with dysgenesis of neuronal brain tissues and vascular malformations and in the majority are asymptomatic. Intracranial lipomas on magnetic resonance imaging (MRI) may mimic late subacute hemorrhage due to similar radiological features. Due to the tight adhesion of the lipoma to the surrounding nerve structures and vessels, complete removal is difficult and does not guarantee the disappearance of symptoms.

CASE DESCRIPTION

We present the case of a 42-year-old woman with chronic headaches and short-term memory impairment who was admitted to the emergency room after an out-of-hospital brain MRI with suspected ruptured right middle cerebral artery (MCA) aneurysm and late subacute intracranial hemorrhage. In the hospital, after clinical evaluation, emergency computed tomography (CT) angiography was performed, which revealed an unruptured fusiform aneurysm located in the right MCA trifurcation surrounded by an extremely hypodense lesion corresponding to fat in the right Sylvian fissure. No features of intracranial hemorrhage were present. The diagnosis of intracranial lipoma was finally confirmed after the MRI of the brain with a fat suppression sequence. Surgical treatment was not attempted, and the patient was treated conservatively with a satisfactory general outcome.

CONCLUSION

A Sylvian fissure lipoma may be associated with a fusiform aneurysm in the MCA trifurcation. By modifying the standard MRI protocol and performing a CT scan, an intracranial lipoma can be detected and a late subacute intracranial hemorrhage can be excluded.

Surgical techniques for investigating the role of the insula in epilepsy: a review

Intracranial electroencephalography monitoring of the insula is an important tool in the investigation of the insula in medically intractable epilepsy and has been shown to be safe and reliable. Several methods of placing electrodes for insular coverage have been reported and include open craniotomy as well as stereotactic orthogonal and stereotactic anterior and posterior oblique trajectories. The authors review each of these techniques with respect to current concepts in insular epilepsy.

Stereotactic depth electrode investigation of the insula in the evaluation of medically intractable epilepsy

Object

The authors describe their experience with stereotactic implantation of insular depth electrodes in patients with medically intractable epilepsy.

Methods

Between 2001 and 2009, 20 patients with epilepsy and suspected insular involvement during seizures underwent intracranial electrode array implantation at the authors' institution. All patients had either 1 or 2 insular depth electrodes placed as part of an intracranial array.

Results

A total of 29 insular depth electrodes were placed using a frontal oblique trajectory. Eleven patients had a single insular electrode placed and 8 patients had 2 insular electrodes placed unilaterally. One patient had bilateral insular electrodes implanted. Postoperative imaging demonstrated satisfactory placement in all but 1 instance, and there was no associated morbidity or mortality. Fourteen patients underwent a subsequent resection, involving the frontal lobe (9 patients), temporal lobe (4), or frontotemporal lobes (1), and of these, 11 currently have Engel Class I outcome. Two patients (10%) had seizures originating within the insula and another 5 patients (25%) demonstrated early specific insular involvement. Neither patient with an insular seizure focus went on to resection. All 5 of the patients with early specific insular involvement underwent an insula-sparing resective procedure with Engel Class I outcome in all cases.

Conclusions

Stereotactic placement of insular electrodes via a frontal oblique approach is a safe and efficient technique for investigating insular involvement in medically intractable epilepsy. The information obtained from insular recording can be valuable for appreciating the degree of insular contribution to seizures, allowing localization to the insula or clearer implication of other sites.

Microsurgery of epileptic foci in the insular region

OBJECT

The insular region has long been neglected in the investigation and treatment of refractory epilepsy. Surgery in the insular region is rarely performed because of the risk of injury to the opercula, the arteries transiting on the surface of the insula, and the deep structures such as the basal ganglia and the internal capsule. This study was undertaken to report the results of insular surgery using modern microsurgical techniques in patients with epilepsy.

METHODS

The authors performed a retrospective study of cases involving patients who underwent surgery for insular lesions associated with epilepsy over the last 10 years. In the majority of patients, intracranial electrodes were implanted with neuronavigation guidance to confirm the localization of the epileptic foci.

RESULTS

Nine patients underwent insular surgery: 7 for refractory epilepsy with no tumor and 2 for tumors associated with seizures. Four of the resections were performed in the left hemisphere. After an average follow-up of 54 months (range 14-122 months), Engel Class IA outcome had been achieved in 6 of 7 cases in the Epilepsy Surgery Group. The remaining patient had an Engel Class III outcome after partial insular resection but later became seizurefree (Engel Class IA) following insular Gamma Knife surgery. Postoperatively, the majority of patients suffered from minor reversible hemipareses that disappeared completely within a few months. There was no surgical mortality.

CONCLUSIONS

Insular surgery is both safe and beneficial when it is well planned and performed with modern microsurgical techniques and good anatomical knowledge. Insulectomy is associated with little permanent morbidity and a high rate of seizure control. To the authors' knowledge, this is the first series of insulectomies predominantly performed for refractory epilepsy since those performed by Penfield.

Microsurgical removal of sylvian fissure lipoma with pterion keyhole approach-case report and review of the literature

BACKGROUND

Intracranial lipomas are thought to be congenital in origin and are very rare, representing 0.1% to 1.7% of all intracranial tumors. Most ICLs are located at midline. Lipomas at sylvian fissure are extremely rare. They are slow growing, and biological course is favorable even without surgical treatment. A Medline search of the literature from 1965 to 2007 revealed only 13 cases of sylvian fissure lipomas reported. Of 9 patients with sylvian fissure lipoma diagnosed during life, 6 patients were operated on with no mortality and got improvement of symptoms. Surgical intervention should be considered if there are problems such as compressive effect or resistance to anticonvulsive medical treatment.

CASE DESCRIPTION

We report a 57-year-old woman with a sylvian fissure lipoma presenting with persistent intractable headache. Imaging study showed a lobular nonenhanced lesion associated with abnormal vessels in the right sylvian fissure. The patient underwent minimally invasive pterion keyhole approach, and the lipoma was successfully and totally removed. Headache and subsided postoperatively.

CONCLUSIONS

There are only few cases of sylvian fissure lipomas in which surgical excision has been attempted. Because of improvement of microsurgical techniques, direct surgical approach with total removal of lipomas, via a minimally invasive pterion keyhole approach, is feasible. Therefore, it should be kept in mind that the primary goal of the surgery is adequate decompression; and total removal may be achieved if the lesion permits.

Cerebral lipoma and the underlying cortex of the temporal lobe: pathological features associated with the malformation

Intracranial lipomas are believed to be congenital malformations rather than true neoplasms, resulting from the abnormal differentiation of the meninx primitiva, the undifferentiated mesenchyme. We report here the surgical pathological features of a lipoma that was located on the cerebral surface of an abnormally formed fissure, and the underlying cortex of the middle temporal gyrus of a 20-year-old woman. The mass was composed of typical adipose tissue in which a large number of blood vessels were present. Thick connective tissue associated with the arachnoid membrane covered the cortical surface. The cortex exhibited a polymicrogyric configuration in which the cortical ribbon was abnormally undulated and excessively folded. Reelin-immunolabeled Cajal-Retzius-cell-like cells were observed frequently in the fused molecular layer. The cortical lamination underlying the molecular layer was poorly defined. Along the border between the connective tissue and cortical surface, there was a narrow zone in which the mesenchymal and neuronal tissues were intermingled, and where immunohistochemical and ultrastructural investigations disclosed disruption of the basal lamina, prominent astrocytosis, and abundant axonal and synaptic profiles. These findings suggest that focal disturbances in cerebral cortical development occur in association with the development of lipomas.

Le lobe de l’insula et les épilepsies partielles

The role of the insular lobe in temporal lobe epilepsy (TLE) has often been suggested but never directly demonstrated. In this article, we review data from recent literature and from our stereo-electroencephalographic (SEEG) recordings in patients referred for temporal lobe epilepsy surgery (TLE). Our description of the clinical features of insular lobe seizures is based on data from video and SEEG ictal recordings and direct electric cortical stimulation in a population of 50 consecutive patients whose seizures, on the basis of scalp video EEG recordings, were suspected to originate from, or to rapidly propagate to, the peri-sylvian cortex. A total of 144 intra-insular electrodes have been implanted in this series of patients. In six patients a stereotyped sequence of ictal symptoms could be identified on the basis of electro-clinical correlations. The clinical presentation of insular lobe seizures was that of simple partial seizures occurring in full consciousness, beginning with a sensation of laryngeal constriction followed by paresthesiae that were often unpleasant affecting large cutaneous territories. These initial symptoms were eventually followed by dysarthric speech and/or elementary auditory hallucinations, and seizures often ended with focal dystonic postures. The insular origin of these symptoms was supported by the data from functional cortical mapping of the insula using direct cortical stimulations. We were able to reproduce several of the spontaneous ictal symptoms in the six patients with insular seizures. Moreover, from the whole set of insular stimulations that we performed it could be concluded that the insular cortex is involved in somatic, vegetative and visceral functions to which spontaneous ictal insular symptoms are related. The observation of the insular symptoms sequence at the onset of seizures in patients who are candidates for TLE surgery strongly suggests that the epileptic focus is located in the insular lobe. It entails the risk of unsuccessful temporal lobectomy and should lead: i) to reconsider the indication of temporal lobectomy and; ii) to explore directly the ictal activity of both mesio-temporal and insular cortices before making any decision regarding epilepsy surgery.

Clinical manifestations of insular lobe seizures: a stereo-electroencephalographic study

PURPOSE

In this study, we report the clinical features of insular lobe seizures based on data from video and stereo-electroencephalographic (SEEG) ictal recordings and direct electric insular stimulation of the insular cortex performed in patients referred for presurgical evaluation of temporal lobe epilepsy (TLE).

METHODS

Since our first recordings of insular seizures, the insular cortex has been included as one of the targets of stereo-electroencephalographic (SEEG) electrode implantation in 50 consecutive patients with TLE whose seizures were suspected to originate from, or rapidly to propagate to, the perisylvian cortex. In six, a stereotyped sequence of ictal symptoms associated with intrainsular discharges could be identified.

RESULTS

This ictal sequence occurred in full consciousness, beginning with a sensation of laryngeal constriction and paresthesiae, often unpleasant, affecting large cutaneous territories, most often at the onset of a complex partial seizure (five of the six patients). It was eventually followed by dysarthric speech and focal motor convulsive symptoms. The insular origin of these symptoms was supported by the data from functional cortical mapping of the insula by using direct cortical stimulations.

CONCLUSIONS

This sequence of ictal symptoms looks reliable enough to characterize insular lobe epileptic seizures (ILESs). Observation of this clinical sequence at the onset of seizures on video-EEG recordings in TLE patients strongly suggests that the seizure-onset zone is located not in the temporal but in the insular lobe; recording directly from the insular cortex should occur before making any decision regarding epilepsy surgery.

Image-guided Transsylvian, Transinsular Approach for Insular Cavernous Angiomas

OBJECTIVE

Surgical treatment of cavernomas arising in the insula is especially challenging because of the proximity to the internal capsule and lenticulostriate arteries. We present our technique of image guidance for operations on insular cavernomas and assess its clinical usefulness.

METHODS

Between 1997 and 2003, with the guidance of a frameless stereotactic system (BrainLab AG, Munich, Germany), we operated on eight patients who harbored an insular cavernoma. Neuronavigation was used for 1) accurate planning of the craniotomy, 2) identification of the distal sylvian fissure, and, finally, 3) finding the exact site for insular corticotomy. Postoperative clinical and neuroradiological evaluations were performed in each patient.

RESULTS

The navigation system worked properly in all eight neurosurgical patients. Exact planning of the approach and determination of the ideal trajectory of dissection toward the cavernoma was possible in every patient. All cavernomas were readily identified and completely removed by use of microsurgical techniques. No surgical complications occurred, and the postoperative course was uneventful in all patients.

CONCLUSION

Image guidance during surgery for insular cavernomas provides high accuracy for lesion targeting and permits excellent anatomic orientation. Accordingly, safe exposure can be obtained because of a tailored dissection of the sylvian fissure and minimal insular corticotomy.

[Cerebellopontine angle lipoma: clinical case]

Lipomas of the cerebellopontine angle are extremely rare. These tumors are probably maldevelopment lesions which can cause slowly progressive neurological symptoms. Including the present case, 90 lipomas in this localization have been described in the literature. The authors report a case of cerebellopontine angle lipoma in a 44-year-old male patient who suffered right hearing loss and tinnitus during seven months. The literature concerning this rare cerebellopontine angle tumor is review. The symptoms, radiological features and surgical management are discussed.

Surgical resection of intrinsic insular tumors: complication avoidance

OBJECT

Surgical resection of tumors located in the insular region is challenging for neurosurgeons, and few have published their surgical results. The authors report their experience with intrinsic tumors of the insula, with an emphasis on an objective determination of the extent of resection and neurological complications and on an analysis of the anatomical characteristics that can lead to suboptimal outcomes.

METHODS

Twenty-two patients who underwent surgical resection of intrinsic insular tumors were retrospectively identified. Eight tumors (36%) were purely insular, eight (36%) extended into the temporal pole, and six (27%) extended into the frontal operculum. A transsylvian surgical approach, combined with a frontal opercular resection or temporal lobectomy when necessary, was used in all cases. Five of 13 patients with tumors located in the dominant hemisphere underwent craniotomies while awake. The extent of tumor resection was determined using volumetric analyses. In 10 patients, more than 90% of the tumor was resected; in six patients, 75 to 90% was resected; and in six patients, less than 75% was resected. No patient died within 30 days after surgery. During the immediate postoperative period, the neurological conditions of 14 patients (64%) either improved or were unchanged, and in eight patients (36%) they worsened. Deficits included either motor or speech dysfunction. At the 3-month follow-up examination, only two patients (9%) displayed permanent deficits. Speech and motor dysfunction appeared to result most often from excessive opercular retraction and manipulation of the middle cerebral artery (MCA), interruption of the lateral lenticulostriate arteries (LLAs), interruption of the long perforating vessels of the second segment of the MCA (M2), or violation of the corona radiata at the superior aspect of the tumor. Specific methods used to avoid complications included widely splitting the sylvian fissure and identifying the bases of the periinsular sulci to define the superior and inferior resection planes, identifying early the most lateral LLA to define the medial resection plane, dissecting the MCA before tumor resection, removing the tumor subpially with preservation of all large perforating arteries arising from posterior M2 branches, and performing craniotomy with brain stimulation while the patient was awake.

CONCLUSIONS

A good understanding of the surgical anatomy and an awareness of potential pitfalls can help reduce neurological complications and maximize surgical resection of insular tumors.

Intracranial lipoma of the sylvian fissure. Case report and review of the literature

The authors present a rare case of lipoma of the sylvian fissure found in a 34-year-old man who presented with seizures. The patient underwent craniotomy and an attempted resection of the lesion, which was initially believed to be a dermoid tumor. The imaging characteristics of dermoids and lipomas are extremely similar. Given the difference in the natural history and resectability of these lesions, lipomas should be included in the differential diagnosis of lesions with imaging characteristics similar to dermoids. Currently, tumor location, density of the lesion or computerized tomography scans, and signal homogeneity of the lesion on magnetic resonance images can help one to distinguish these radiographically similar, but pathologically different, entities. As this case confirms, resection of a sylvian fissure lipoma is extremely difficult and potentially dangerous; in addition it is unlikely to improve symptoms. A short review of 10 cases reported in the literature and therapeutic options for these lesions are also discussed.

The insular lobe: physiopathological and surgical considerations

OBJECTIVE

Surgery of the insula represents a technical challenge, because of the proximity of the internal capsule to the lenticulostriate arteries and the lack of certainty concerning its functionality. Using intraoperative direct cerebral stimulation, combined with neuronavigation, the authors operated on 12 insular gliomas. On the basis of this experience, the physiopathological and surgical implications are discussed.

METHODS

A low-grade insular glioma, revealed by seizures, was diagnosed in 12 right-handed patients with a normal neurological status. Preoperative magnetic resonance imaging showed that, according to Yasargil's classification system, three patients harbored Type 3 lesions and nine patients had Type 5 lesions (10 tumors on the right side and 2 on the left dominant side). All patients underwent surgery using direct cerebral stimulation, under general anesthesia in nine patients (motor mapping) and under local anesthesia in three patients (sensorimotor and language mapping). Ultrasonography and/or neuronavigation was used in all cases. Preoperative angio-computed tomographic scanning showed the lenticulostriate arteries in two patients.

RESULTS

The internal capsule was systematically detected, and the language areas were identified within the left insula in the awake patients. The lenticulostriate arteries were seen in two patients. Seven patients presented an immediate postoperative deficit; six of them recovered completely within 3 months. Four resections were total, six were subtotal, and two were partial (left insula).

CONCLUSION

The use of intraoperative direct cerebral stimulation and neuronavigation allows surgery of the insula with minimization of the risk of sequelae, but its use is still limited with regard to the dominant hemisphere, owing to the essential role of this structure in language.

Lipoma of the interpeduncular fossa: demonstration by CT and MRI

A case of intracranial lipoma located in the interpeduncular fossa of a young woman is presented. Since the patient suffers only nonspecific headache, no treatment was performed. To our knowledge this is the only which was demonstrated by magnetic resonance images (MRI) in the English language literature.

Multiple intracranial lipoma: a case report

We report on a male epileptic patient, presently 27 years old, who has suffered complex-partial attacks for 19 years. Under treatment with carbamazepine the seizures were completely controlled. In addition, the patient exhibited partial hypopituitarism. CT and MRI revealed the presence of 2 lipomas, one located within the optico-chiasmatic cistern and the other one in the medial temporal lobe. To our knowledge, this combination of the generally rare lesions has not been described yet.

Intrinsic tumors of the insula: a prospective surgical study of 30 patients

Intrinsic insular tumors are frequently excluded from surgical treatment. The authors propose a more extensive approach to these lesions based on the results of this prospective series. From September 1993 to January 1995, 30 patients (18 males and 12 females; mean age 42 years) harboring benign (15 patients) or malignant (15 patients) tumors involving the insula underwent surgical treatment. The dominant and nondominant hemispheres were both affected in 15 cases. Two groups were defined on the basis of preoperative magnetic resonance (MR) imaging: 14 lesions were restricted to the insula and the corresponding opercula; the other 16 lesions also involved other mesocortical and/or allocortical areas. Most patients displayed only mild preoperative symptoms. The median score according to the Karnofsky performance scale was 90. Microsurgical removal was achieved via a transsylvian approach in nine cases and via a frontal and/or temporal approach in 21 cases. According to early postoperative MR imaging, complete tumor removal (100%) was seen in five patients, nearly complete (> 80%) in 21, and incomplete resection (50%-80%) in four patients. There was no operative mortality; 19 patients (63%) experienced immediate postoperative morbidity, including reduced performance. After a mean follow-up review of 8.5 months two of 21 patients suffered permanent deficits, accounting for an overall operative morbidity of 10%. At the mean time of review, three patients with Grade IV tumors had died of tumor recurrence. The authors conclude that low-grade intrinsic insular tumors, as well as Grade III tumors, can be removed with favorable results in the majority of patients. Surgery to excise glioblastomas should only be considered for patients with good preoperative performance and young age.

Surgical treatment of partial epilepsy arising from the insular cortex. Report of two cases

Despite its documented connections with many limbic structures, the role of the insula in the etiology of partial seizures is poorly understood. Two patients are described in whom lesions of the insula were associated with intractable partial seizures. In the first patient, the seizures involved visceral sensory hallucinations followed by motor automatism. Seizures in the second patient began with somatic sensory hallucinations and then produced visceral motor effects. Both patients were found to have low-grade astrocytomas of the insula. In both instances, resection of the lesion and adjacent insular cortex resulted in a cure of the seizures. These cases are placed within the context of the existing literature on the subject.

Lipoma of the cerebral cortex: case report

The first clinically diagnosed and successfully operated case of a symptomatic lipoma involving the cerebral cortex is reported. The patient presented with severe headaches and recurring focal seizures with secondary generalization. Computer tomography scan and magnetic resonance imaging suggested a left frontoparietal lipoma. After undergoing a craniotomy and tumor excision, the patient has shown resolution of headaches and seizures at 1-year follow-up. Lipomas of the cerebral cortex should be excised if symptomatic and accessible.

Intracranial lipoma associated with cerebral saccular aneurysm. Case report

The authors present a case of lipoma in the sylvian fissure associated with a saccular aneurysm of the middle cerebral artery. The aneurysm was successfully clipped following the partial resection of the tumor. This is the first reported case of this combined pathology. The value of cerebral angiography in this disease entity and the possible etiology of the association of an aneurysm with a lipoma are discussed.

Intracranial lipomas: current perspectives in their diagnosis and treatment

Intracranial lipomas are very rare lesions, which are probably congenital. Though they can occur anywhere in the intracranial space, a high proportion of cases tend to be ++located around the midline. They are usually asymptomatic. When symptoms do occur, they are frequently the result of co-existing general clinical conditions. Lipomas used to be reported mainly as incidental findings at autopsy, but advances in neuroimaging techniques have greatly improved the likelihood of their being discovered during life. Surgical extirpation is not necessary in the majority of patients, many of whom show remarkable clinical improvement following shunt procedures for obstructive hydrocephalus (when present) as well as vigorous treatment of co-existing conditions.

Intracranial lipomas

Intracranial lipomas are very rare, probably congenital lesions. Though they can occur anywhere in the intracranial space, a good proportion of cases tend to be located around the midline. Review of the literature as well as our own three cases--which forms the basis of this article--shows that they are mostly asymptomatic. When symptoms occur, they are frequently the result of coexisting general clinical conditions. Lipomas used to be reported mainly as incidental findings at autopsy. Advances in neuro-imaging techniques have vastly improved the likelihood of their being discovered during life. At present however, significant increase in the reported incidence of these tumours is yet to be seen. Surgical extirpation of the tumour is not considered necessary in the majority of patients, many of whom show remarkable clinical improvement following shunt procedures for obstructive hydrocephalus as well as treatment of coexisting conditions such as epilepsy.

Lipoma of the midbrain. Post-mortem finding in a patient with breast cancer

Intracranial lipomas are rare, usually do not have clinical expression and are located more frequently in the corpus callosum. Other locations include the spinal cord, midbrain tectum, superior vermis, tuber cinereum, infundibulum and more rarely cerebellopontine angle, hypothalamus, superior medullary velum and insula. We report the case of a lipoma of the left inferior colliculus which was a post-mortem finding in a woman who died of breast cancer. Although there are reports of intracranial lipomas in patients with malignant tumors there is no explanation for the co-existence of the two tumors. The present tumor also includes a segment of a nerve which is not uncommon, but a less common finding was the presence of nests of Schwann cells within it, shown by immunohistochemistry.

Lipoma of the sylvian region

An exceptional case of lipoma of the sylvian region is described and the other seven reported cases are reviewed. The sylvian fissure is the most rare site of intracranial lipomas. Sylvian lipomas may be asymptomatic or present with epileptic seizures due to irritation of the cortex of the sylvian fissure. Only two previous cases have been diagnosed during life by computerized tomography and operated on; the deep location of these lipomas and their adherences to the sylvian cortex and the branches of the middle cerebral artery make radical removal impossible and dangerous.

Lipoma of the infundibulum. Case report

Lipomas of the infundibulum are extremely rare and may not be recognized radiologically, even on computerized tomography (CT) scanning, if the tumor is less than 20 mm in diameter. A questionable CT diagnosis in the presence of endocrinological symptoms may justify an operation by microsurgical technique on the retrochiasmatic region. In the case reported, microsurgical removal of a small infundibular lipoma was successfully accomplished.

Lipoma of the septum pellucidum: case report

Intracranial lipomas are relatively rare maldevelopmental lesions that most characteristically occur in the corpus callosum. Although their occurrence in many other locations has been described, no report can be found of lipomas occurring in the septum pellucidum. A case is presented to document the occurrence of a lipoma of the septum pellucidum and to describe the magnetic resonance image appearance of an intracranial lipoma.

Lipoma of the quadrigeminal plate cistern

Two cases of quadrigeminal plate cistern lipoma detected by CT scan, one of which produced impairment of vertical gaze, are reported. The problems of diagnosis and therapy of intracranial lipomas are briefly discussed.

Lipoma in the cerebellopontine angle

A case of lipoma in the cerebellopontine angle is reported. Intracranial lipomas are very rare, especially in the cerebellopontine angle. To our knowledge, only four cases, including our own, have been operated upon. Until now, total extirpation has not been possible. The singular appearance on computed tomography scanning of this dysembryoplasia is presented together with a bibliography of this subject.