Subtemporal Approach Research Articles

Transcranial surgery for pituitary tumors performed by Sir Victor Horsley.

To describe the clinical details and the operative method used in pituitary tumors by Sir Victor Horsley (1857-1916), which represent the earliest attempts at pituitary surgery. Horsley's case books and postmortem records, archived at the National Hospital, Queen Square, London, were studied for patients with a primary diagnosis of a pituitary tumor admitted during the period 1886 to 1916 who were treated surgically. Contemporary records of nonpituitary cases were also examined to study aspects of Horsley's operative method. Four patients (three men and one woman) underwent craniectomy for removal of a pituitary tumor via the subtemporal approach between 1904 and 1907. All four patients experienced significant impairments of visual fields or visual acuity; one patient had severe trigeminal neuralgia. Evidence of acutely raised intracranial pressure was present in one patient. All patients underwent craniectomy under chloroform anesthesia. One patient died on the day of surgery, and the postmortem findings are presented. In the other three patients, neurological morbidity was recorded in the postoperative period in the form of new cranial nerve deficits, monoparesis with dysphasia, and seizures. The patient with trigeminal neuralgia experienced partial relief and was readmitted later for reexploration and Gasserian ganglionectomy via the same route. Four contemporary nonoperative cases of pituitary tumor are also presented. These cases provide insight into the presentation and operative treatment of pituitary tumors during the pre-Halsted era.

Trigeminal Neuroma: Analysis of Surgical Experience with 73 Cases

We reviewed the clinical and radiological features of 73 cases of trigeminal neuromas treated with radical surgery. The records for 73 patients with trigeminal neuromas who were surgically treated in the neurosurgery department of King Edward VII Memorial Hospital and Seth Gordhandas Sunderdas Medical College (Mumbai, India), between 1989 and 2001, were retrospectively analyzed. The appropriateness of the selected surgical route was studied. The postoperative and follow-up data for the patients were analyzed, to determine the outcomes of radical surgery. In addition to the other presenting features of trigeminal neuromas, nine patients presented with the rarely reported symptom of pathological laughter. Three approaches were observed to be appropriate for treatment of these tumors, i.e., the infratemporal fossa interdural approach, the lateral basal subtemporal approach, and the retrosigmoid approach. In 51 cases (70%), total tumor excision was achieved. Two patients died during the postoperative period. With an average follow-up period of 38 months, there has been a recurrence in 1 case and 71 patients are leading independent and active lives. Radical surgery is associated with excellent clinical outcomes and long-term tumor control. A majority of tumors, even those that are large and multicompartmental, can be removed in a single surgical stage and exposure.

Far posterior subtemporal approach to the dorsolateral brainstem and tentorial ring: technique and clinical experience.

Surgical access to the posterolateral mesencephalon or tentorial ring can be problematic, depending on the angle of the tentorium and associated venous structures. A far posterior subtemporal approach was developed that uses the wide opening of the tentorium and the option of supratentorial retraction of the cerebellum to provide an excellent angle of approach to this region. Details of this technique and a series of eight patients with lesions treated by this approach are presented. Seven cavernous malformations and one dural arteriovenous malformation were approached in eight patients. In this far posterior subtemporal approach, a horseshoe incision is centered slightly behind the ear, with the caudal extent of the craniotomy defined by the temporal fossa floor. The entry of the vein of Labbé into transverse sinus is identified intradurally. If the vein enters anteriorly in the exposure, it is mobilized. Retractors are then placed, and the tentorium is visualized and opened laterally, avoiding the trochlear nerve. A thin, tapered retractor can be used to retract the cerebellum posterolaterally away from the brainstem. This approach was used to treat eight patients, and their lesions were successfully resected. Seven patients experienced good outcomes, and one patient, who presented with Hunt-Hess Grade IV subarachnoid hemorrhage from a dural arteriovenous malformation, experienced a fair outcome. The far posterior subtemporal approach is effective for approaching carefully selected lesions of the posterolateral mesencephalon and tentorial ring.

Surgery for the cavernous angioma in the brainstem

Surgical treatment of the cavernous angioma in the brainstem needs careful consideration of indication, timing of surgery, and selection of the optimal surgical approach. We report three cases of cavernous angioma in the brainstem treated surgically. Case 1 is a 54-year-old woman presented with hemorrhage in the pons. As she deteriorated with repeated hemorrhage, surgical resection was done via the fourth ventricle. Postoperatively, she became alert and showed no additional neurological deficits. Case 2 is a 44-year-old woman presented with hematoma in the right side of the midbrain. As she suffered repeated hemorrhage extending to the right thalamus, resulting in deterioration and left hemiparetic, direct surgery was performed via the right subtemporal approach. Postoperatively, she became alert and the hemiparesis improved. Case 3 is a 49-year-old man presented with repeated hemorrhage in the medulla oblongata. Neuroimagings disclosed the cavernous angioma was associated with a venous malformation in the vicinity. Only the cavernous angioma was surgically resected via the fourth ventricle. Postoperative course was uneventful, and he returned to his job 3 weeks after surgery. Clinically manifested cavernous angioma due to repeated hemorrhage needs surgical resection. Optimal surgical approach should be selected so as the normal vital structures are not compromised. Careful dissection is also mandatory not to press and damage the surrounding vital structures.

Surgical treatment of basilar top aneurysms

Surgical treatment of basilar top aneurysms is still challenging to the neurosurgeons specializing in the treatment of cerebrovascular disease. During the past 18 years, the senior author (DH Han) operated on 79 posterior circulation aneurysms. The number of the basilar bifurcation aneurysms (BBAA) was 38 (49%) in 37 patients, 56% (20 patients) of whom showing multiple aneurysms. Modified pterional approach was the choice of treatment for most of these aneurysms (37 patients), and only 1 patient underwent subtemporal approach. Through the modified pterional approach, senior author achieved aneurysmal neck clipping in 34 aneurysms, and wrapping in the other 4. The overall operative mortality and morbidity were 9% and 31% each, and in patients with good preoperative Hunt–Hess grade (I–II), good results were achieved in 75%, which was comparable to the other series. Transient third nerve palsy was the most frequent postoperative complication that lasted for 2.6 months on average. The surgical tactics of the modified pterional approach used by the author are described with the analysis of the clinical characteristics of his series.

Microanatomy of Medial Temporal Area and Subtemporal Amygdalohippocampectomy

For seizure control in temporal lobe epilepsy, the head of the hippocampus to the choroidal point, parahippocampal gyrus, entorhinal area, uncus, and at least the basolateral nucleus of the amygdala should be completely removed. The subtemporal approach should be selected for removal of these structures, and it does not interrupt the temporal stem and optic radiation. Pre- and postoperative neuropsychological examinations revealed that there is no significant decline of scores of various examinations including WAIS, WMS, Randt memory, and verbal associates learning tests, even if the resection were performed on the language dominant side. Seizure control for the 20 non-lesional patients operated with this approach is 60% (Class I and II), without definite permanent complications.

Surgical management of unruptured basilar artery bifurcation aneurysms

The basilar artery (BA) bifurcation is the most common site for aneurysms arising from the posterior circulation. Their inhospitable location, nested within the narrow confines of the interpeduncular fossa anterior to the brainstem, coupled with the rich network of adjacent critical thalamoperforating arteries irrigating the midbrain and thalamus, pose difficult anatomical obstacles for the surgeon. The age old adage that the only cure for intracranial aneurysms remains exclusion from circulation before rupture still holds true. Although management of unruptured aneurysms in general is still controversial, unruptured aneurysms of the BA bifurcation can be treated surgically with acceptable rates of morbidity. The clinician must gather and weigh all clinical, pathological, and radiological data when formulating recommendations for the individual patient. In the present report the authors describe their current technique for the surgical management of unruptured BA bifurcation aneurysms; this represents the culmination of the senior author's (N.K.) experience in the management of both ruptured and unruptured BA bifurcation aneurysms. A modified, right-sided subtemporal transtentorial approach has been adopted in all cases of isolated unruptured BA bifurcation aneurysms. Technical nuances are described.

Incidental Intracranial Aneurysms

This month's issue of Neurosurgical Focus concentrates on the management of intracranial aneurysms. The authors of the lead article review risk factors for postprocedure morbidity after treatment of incidental intracranial aneurysms. The findings in this manuscript document that incidental intracranial aneurysms may be treated and result in less morbidity than noted in the International Study of Unruptured Intracranial Aneurysms (ISUIA) report. The current study reviews a single group's experience with the management of intracranial aneurysms, taking a comprehensive team approach to the management of these lesions. Thus, it cannot easily be correlated with the ISUIA trial. The main finding of this study suggests that surgical management may involve a morbidity rate as high as reported in the ISUIA trial. The significant findings in this paper are that aneurysms greater than 13 mm in size and those with broad and calcified necks portend a greater risk for surgical morbidity. In the past, familial predisposition toward cerebral aneurysms has always been described in patients with two or more affected family members. The second manuscript in this issue suggests that first-degree relatives of patients with aneurysms are at higher risk for harboring intracranial aneurysms. The authors analyzed 96 relatives between the ages of 20 and 70 years with three-dimensional fast–spin echo magnetic resonance imaging for the presence of intracranial aneurysms. They found that the incidence of unruptured aneurysms was greater than anticipated. Given the noninvasive means available for evaluating patients, it may be of benefit to have all relatives undergo three-dimensional magnetic resonance imaging. The focus of the final vascular paper is on a single group's experience using the subtemporal approach for the management of basilar bifurcation aneurysms. The authors describe their modifications and technical nuances. This is a superb technical note from a group with considerable experience. This issue focuses on some of the finer details of intracranial aneurysm disease. The reader should gain a greater understanding of the management of patients with unruptured intracranial aneurysms and their first-degree relatives. Moreover, the technical surgical approach for basilar bifurcation aneurysms is superbly reviewed.

Decompressive craniectomy for the management of patients with refractory hypertension: should it be reconsidered?

The management of refractory post-traumatic cerebral oedema remains a frustrating endeavor for the neurosurgeon and the intensivist. Mortality and morbidity rates remain high, despite refinements in medical and pharmacological means of controlling intracranial hypertension. In this retrospective study we have evaluated the efficacy of decompressive craniectomy as a last resort therapy, from the data of nine patients with severe brain injury and delayed cerebral oedema (diffuse injury type III), treated between January 1997 and September 1999. The following parameters were considered: age, Glascow Coma Scale, injury severity, intracranial pressure, CT findings, pupil reaction/posturing. Follow-up period was over at least 2 years and outcome measured on the GOS. Patients have been operated on post-trauma median day 3, mean age 26+/-9, GCS 7+/-3.7, mean APACHE II 16+/-6.4, mean ISS 27.8+/-16.1, mean preoperative ICP 37.7+/-10.0, mean postoperative ICP 18.1+/-16.01. Seven patients have been operated by a frontotemporoparietal approach (six of them bilateral, one unilateral) and two patients have been operated on by a bilateral subtemporal approach. Mortality rates 22%, severe disability 11%, good recovery 66%. Patients with STBI, developing delayed intracranial hypertension caused by diffuse cerebral oedema, definitely benefit from craniectomy when current medical treatment has failed. The encouraging results of outcome in this and more recent studies, indicate the need for a multi-institutional randomized prospective study evaluating early indicators of raised ICP, timing, efficacy of treatment, operative technique and complications of decompressive craniectomy.

The subtemporal and preauricular infratemporal approach for removal of skull base chordomas and chondrosarcomas

The subtemporal and preauricular infratemporal fossa approach provides direct access to the middle cranial fossa, petrous bone, clivus, and cavernous sinus. This approach is ideally suited for use in the resection of chordomas and chondrosarcomas because most are extradural tumors. This approach requires a thorough knowledge of the surgical anatomy of the middle cranial fossa, cavernous sinus, temporal bone, and clivus. A frontotemporal craniotomy is made, and an orbitozygomatic osteotomy is performed to provide a low approach to this area. Dissection is performed extradurally under the temporal lobe to identify the petrous segment of the internal carotid artery. The artery is exposed completely in its entire course through the temporal bone and displaced laterally. The temporal bone and clivus are drilled medial to the petrous internal carotid artery. The surgeon approaches the area in front of the brainstem from an anterolateral direction.

Le périoste temporal : étude anatomique et intérêt chirurgical

The periosteum of the temporal area is mentioned at different places in the literature: either against the osseous plane like everywhere in the human body, or between the deep and the superficial temporal fascia. The subperiosteal subtemporal approach in craniofacial surgery in children is in favour of a juxta-osseous localization of the periosteum. Ten premature still-born neonates and two adults cadavers have been dissected for this study and, permit anatomical and histological (with HES coloration) studies. With every specimen, the authors concluded that the temporal periosteum is against the outer table of the calvarium. It became thinner in adults because of direct insertions of the temporalis muscle in the calvaria. An anatomical description of the layers of the temporal area is realised and discussed with an extensive review of the literature. The authors have proposed a subperiosteal subtemporal approach in craniostenosis surgery.

Astrocytomas of the cerebral peduncle in children: surgical experience in seven patients.

Cerebral peduncle tumors are rare in childhood but often consist of benign astrocytomas. Surgical resection, however, is considered to be detrimental because of the highly sensitive neural structures. These tumors are often treated by radiation therapy (RT). We resected such tumors in seven patients, whom we then followed up without adjuvant therapy. The surgical approach and postoperative course are analyzed. Seven children, ranging in age from 4 to 16 years, were treated from 1993 to 2000. Tumors showed extension in various directions to the thalamus, pons and neighboring cisterns. All were treated by surgical resection through a subtemporal approach: total resection was achieved in three and subtotal resection in four. Operative complications were minimal. Two patients were worse after surgery, albeit temporarily, in motor, oculomotor or memory functions. All the tumors were benign astrocytomas. None of the patients received postoperative RT. Only one patient had a recurrence during the follow-up period, which ranged from 1 year to 8.5 years in duration. Benign astrocytomas of the cerebral peduncle are amenable to radical tumor resection by an appropriate surgical approach and with microsurgical techniques. Even following subtotal resection, these tumors frequently remain stable or involute. These children can be spared RT.

Brain-stem abscess successfully treated by microsurgical drainage: A case report

Brain-stem abscess is an uncommon condition associated with high mortality. The best method of treatment is not yet defined. It can be managed by medical treatment alone, stereotactic aspiration of the pus and medical treatment, or surgical excision/drainage of the abscess. We present a case of large brain-stem abscess, treated successfully by surgical drainage after the failure of medical treatment. The patient had a large brain-stem abscess extending from the mid-brain down to the lower pons. She was in a poor neurological condition pre-operatively, and was worsening despite intravenous antibiotics. The abscess was coming close to the surface in the lateral aspect of the mid-brain. The presumed source of infection was multiple dental abscesses. The brain-stem abscess was approached by a subtemporal transzygomatic approach and drained completely after making an incision on the lateral surface of the mid-brain. After the operation, the patient showed steady improvement. At six months after the surgery, the patient was fully conscious, talking fluently, and walking with the help of a walker. Her hemiparesis and co-ordination were improving. Surgical drainage of a brain-stem abscess is indicated when medical therapy fails. Proper anatomical knowledge of the brain-stem and the selection of appropriate surgical approach is important for safe drainage of the abscess. [Neurol Res 2001; 23: 855-861]

Neuroprotective effects of the CRF1 antagonist R121920 after permanent focal ischemia in the rat.

The neuroprotective effects of a systemically active, highly selective, corticotropin-releasing factor-1 (CRF1) receptor antagonist, R121920 ((7-(dipropylamino)-2,5-dimethyl-3- [2-(dimethylamino)-5-pyridyl] pyrazolo [1,5-a] pyrimidine), was assessed in two rat models of permanent focal cerebral ischemia, where the middle cerebral artery (MCA) was occluded either through the subtemporal approach or using the intraluminal suture technique. R121920 rapidly crossed the blood-brain barrier after intravenous (IV) bolus administration (10 mg/kg), with peak brain concentrations at 5 minutes (2.26 +/- 0.40 microg/mL), which were approximately 2-fold greater than those in plasma (0.98 +/- 0.24 microg/mL). Treatment with R121920 (10 mg/kg IV followed by 5 mg/kg subcutaneously at hourly intervals for 4 hours) significantly (P < 0.001) reduced total (by 40%) and cortical (by 37%) infarct volume at 24 hours after subtemporal MCA occlusion (MCAO). In the intraluminal suture MCAO model, IV administration of R121920 (10 mg/kg) at the time of ischemia onset (and at multiple times thereafter) reduced both hemispheric infarct volume (by 34%, P < 0.001) and brain swelling (by 50%, P < 0.001) when assessed at 24 hours. In this model of focal ischemia, significant reduction (P < 0.05) in both outcome measures was obtained when R121920 administration was delayed up to 1 hour after MCAO. These results further define the antiischemic properties of selective CRF 1 antagonists in two experimental models of permanent focal cerebral ischemia.

A giant internal carotid-posterior communicating artery aneurysm presenting with atypical trigeminal neuralgia and facial nerve palsy in a patient with autosomal dominant polycystic kidney disease: a case report

BACKGROUND In cases of internal carotid-posterior communicating artery (IC-PC) aneurysm, involvement of the trigeminal nerve at its root is rare, and facial nerve palsy is even more unusual. CASE REPORT A large, unruptured IC-PC aneurysm was detected in a 56-year-old man with autosomal dominant polycystic kidney disease (ADPKD), but surgery was not performed because of mild renal dysfunction. Two months later, a sudden, severe headache suggested a subarachnoid hemorrhage, which was ruled out by computed tomography and lumbar puncture. Neurological examination revealed complete oculomotor palsy, atypical trigeminal neuralgia, and facial palsy with gustatory disturbance. Magnetic resonance (MR) imaging revealed a partially thrombosed giant aneurysm that directly compressed the trigeminal nerve root, reached the internal auditory canal, and was adjacent to the facial nerve. The neck of the aneurysm was successfully clipped via a subtemporal transtentorial approach. The postoperative course was uneventful, and all neurological symptoms had resolved within 3 months. CONCLUSIONS We believe that the prosopalgia in this case was atypical trigeminal neuralgia due to direct compression of the trigeminal nerve root by the aneurysmal sac. A contributory cause was stretching of the oculomotor nerve, which contains sensory afferent inhibitory fibers derived from the ophthalmic branch of the trigeminal nerve. The facial palsy was of peripheral type and was accompanied by gustatory disturbance. This is the first reported case of facial palsy caused by an IC-PC aneurysm and also a very rare case of an IC-PC aneurysm clipped by a subtemporal transtentorial approach.

The pretemporal approach: Surgical anatomy, operative technique, and rationale

As a variant of the classic pterional approach, the pretemporal approach aims to combine the advantages of the pterional, temporopolar, and subtemporal approaches, offering enhanced angles of the view and the action of the surgeon: whether the straight downward view of the pterional approach, the anterolateral temporopolar view obtained by pulling back the temporal pole, or the lateral view offered by the subtemporal approach. This enhanced view is accomplished by adding a more extended and basal temporal exposure to the classic pterional craniotomy, as low as the floor of the middle fossa, and exposing completely the temporal pole. The sylvian fissure is split widely, the basal cisterns are opened widely, and the arachnoid adhesions among the frontal and the temporal lobes, tentorial edge, and cranial nerve III are sectioned completely. When necessary, the superficial sylvian vein or veins binding the temporal pole to the sphenoparietal sinus are sacrificed, allowing a posterior retraction (temporopolar exposure) or a superior retraction (subtemporal exposure) of the temporal lobe. The interpeduncular, upper petroclival, middle fossa, sellar and parasellar regions, and anterior portion of the tentorial incisura are within the reach of the pretemporal approach. The inclusion of an orbitozygomatic osteotomy to the pretemporal approach can greatly improve the surgical exposure of such areas. The more basal exposure of the anterior and middle cranial fossae provided by the orbitozygomatic craniotomy allows the treatment of lesions that either arise or extend to the extradural compartment of these regions. The sphenoid, frontal and ethmoidal sinuses, components of the orbit, cavernous sinus, infratemporal fossa, petrous apex, intrapetrous internal carotid artery, and remainder of the middle cranial fossa can be accessed with this approach.

Removal of anterior clinoid process for basilar tip aneurysm: Clinical and cadaveric analysis

The difculty in the operation for basilar tip aneurysm is the restrictionin surgical working space. To resolve this problem, aggressive skull base surgery has been reported, but these techniques are not prevalent. Pterional and subtemporal approaches are commonly used for basilar tip aneurysms. In an attempt to increase the surgical working space during the pterional approach, the anterior clinoid process and the roof of the optic nerve were removed extradurally to increase the mobilization of the intracranial internal carotid artery and optic nerve. The effects of removing the anterior clinoid process and microanatomy in the perioptic area were analyzed by cadaveric procedures in 10 cases (20 sides). With this procedure, the internal carotid artery can be retractedmedially with a spatula 6.1±0.8mm (mean±SD). The length and the area of dural fold in the bone defect region in the optic canal roof are 2.1mm and 13.6mm2 . In 10 clinical cases, this procedure allowed enough space to approach the basilar tip aneurysm without disturbing the internal carotid artery blood flow. The clinical outcome was satisfactory.

Cavernous sinus tuberculoma: diagnostic difficulties in a personal case

BACKGROUNDTuberculoma of the brain is rare, and its location in the cavernous sinus is exceptional. Many factors make the diagnosis difficult, necessitating a surgical procedure.CASE DESCRIPTIONA 44-year-old woman complained of persistent headaches and diplopia. The examination revealed a right cavernous sinus syndrome. Radiologic investigation showed a growing process in the right cavernous sinus, overlapping the sella turcica. The diagnoses of metastasis, tuberculoma, and sarcoidosis were considered, but none of them could be confirmed. A biopsy of the lesion via a subtemporal approach revealed a tuberculoma. Antituberculous treatment led to complete resolution of her symptoms.CONCLUSIONThe diagnosis of a cavernous sinus tuberculoma is difficult; it is confirmed by biopsy. However, a trial of medical treatment, if the results are favorable, may obviate the need for a surgical procedure.

Preservation of large bridging veins of the cranial base: technical note.

Sacrifice of a bridging vein in the cranial base occasionally may cause significant postoperative morbidity. We report a simple method for preserving large bridging veins of the cranial base by reflecting the dura when a subtemporal or transsylvian approach is used. In the subtemporal approach, when a larger bridging vein enters the dura attached to the bone of the temporal base before it empties into the dural sinus, the dura is dissected widely from the bone and is cut vertically toward the medial side of the temporal base in front of the entrance of the vein into the dura. The dura, which includes part of the entrance and interdural course of the vein, is reflected and retracted over the brain. In the transsylvian approach, when the bridging segment of the superficial sylvian vein becomes taut because of retraction of the temporal lobe, the dura is incised along the sphenoid ridge and is dissected and freed from the sphenoid bone. This dura-reflecting technique facilitates brain retraction without exerting tension on the bridging vein of the cranial base and is expected to help avoid injury to bridging veins during neurosurgical procedures.

Zygomatic Anterior Subtemporal Approach for Lesions in the Interpeduncular Cistern

The interpeduncular cistern is a difficult region to approach through conventional methods due to its deep location and important adjacent neurovascular structures. Therefore, it is usually difficult to expose the region sufficiently. Technical problems associated with various surgical approaches have led to emergence of combined approaches and their modifications (i.e., the removal of the zygomatic arch). In addition, a frontotemporal craniotomy is reported to provide a wide exposure of the anterior temporal base, thus allowing oblique access to the interpeduncular cistern with minimal brain retraction. This study describes clinicians' experience and the surgical results of 24 patients who underwent a zygomatic anterior subtemporal approach.