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Objective: Implantation epidermoid cysts have been reported after a variety of surgical procedures. Although carpal tunnel surgery is the most common peripheral nerve operation, there have been no previous reports of these cysts after carpal tunnel decompression. We present a case of an implantation epidermoid cyst after carpal tunnel surgery., Clinical Presentation: A 41-year-old man presented with recurrence of carpal tunnel syndrome and an enlarging mass at the site of his previous carpal tunnel decompression., Intervention: The operation site was re-explored, and a subcutaneous mass was removed. This was histologically shown to be an implantation epidermoid cyst., Conclusion: The possibility of an implanted epidermoid cyst should be considered in any patient who presents with a recurrence of carpal tunnel symptoms and a mass at the site of the previous operation. It is possible that the occurrence of these cysts may be related to the use of polyglactin sutures for wound closure. In this case, the result of surgery was excellent.

Objective: To provide the characteristics and long-term surgical results of patients who present with cerebellopontine angle epidermoids and trigeminal neuralgia (TN) or hemifacial spasm., Methods: A total of 30 patients (23 women, 7 men) who presented with cerebellopontine angle epidermoids and TN (28 patients) or hemifacial spasm (2 patients) between 1982 and 1995 were reviewed, with emphasis being placed on the clinical manifestations, the mechanisms of symptom development, the long-term follow-up results, and the anatomic relationship between the tumor and the surrounding neurovascular structures., Results: The average age of the patients was 37.8 years at symptom onset and 49.3 years at the time of the operation. The tumor-nerve relationships were classified into four types: complete encasement of the nerve by the tumor, compression and distortion of the nerve by the tumor, compression of the nerve by an artery located on the opposite side of the unilateral tumor, and compression of the nerve by an artery on the same side of the tumor. Total resection was achieved in 17 patients (56.7%). Microvascular decompression of the respective cranial nerve was achieved in nine cases of direct arterial compression in addition to tumor removal. The symptom was relieved completely in all cases. In an average follow-up period of 11.5 years, three patients developed recurrent symptoms: two experienced tumor regrowth, and one had arachnoid adhesion., Conclusion: Hyperactive dysfunction of the cranial nerves, especially TN, may be the initial and only symptom that patients with cerebellopontine angle epidermoids experience. The occurrence of TN at a younger age was characteristic of TN patients with epidermoids, in contrast to patients with TN due to a vascular cause. The symptom is elicited by compression of the nerve by the tumor per se, by an artery that is displaced to the nerve, or by both. Careful resection of the tumor, whose capsule occasionally is strongly adherent to the neurovascular structures, is necessary, and microvascular decompression to straighten the neuraxis should be performed in some cases to achieve a complete, permanent cure of symptoms with a low rate of recurrence.

Objective and Importance: A fat component within the ventricles or subarachnoid space in fat-containing tumors such as an epidermoid or a dermoid has been observed in rare instances. However, there have been no reports regarding an increase in the size of such a fat component. We describe the case of an epidermoid tumor with intraventricular fat that showed an increase in size and amount., Clinical Presentation: A 26-year-old woman was admitted with headache and diplopia. Computed tomography and magnetic resonance imaging of the brain revealed a fat-containing suprasellar tumor and widespread fat globules in adjacent sulci and cisterns and within the frontal horn of the lateral ventricle., Intervention: The patient underwent a pterional craniotomy. Removal of the suprasellar tumor was nearly total. Histopathological examination revealed an epidermoid tumor. Sequential magnetic resonance imaging throughout the ensuing 65-month period revealed no evidence of tumor recurrence; however, the intraventricular fat remained and increased in size. The patient underwent surgery via the transcallosal approach at 69 months after the initial operation, and the presence of free-floating oily fat globules was confirmed., Conclusion: In the case of a fat-containing tumor with free fat in the cerebrospinal fluid spaces, careful serial examination is necessary, with particular attention to the possibility of changes in size.

Objective and Importance: Supratentorial epidermoid cysts located on the midline are very rare. We describe the first case of such a cyst arising from the rostral neuropore., Clinical Presentation and Intervention: We report a patient suffering from seizures and progressive frontal syndrome and presenting with a huge cyst developed in the midline at the rostralmost part of the corpus callosum. The patient was operated on, and the cyst was found to be epidermoid., Conclusion: Only six cases of supracallosal epidermoid cysts have been reported. In our case, the involved region was located at the exact limit between lamina terminalis and corpus callosum. This region corresponds to the place of the closing rostral neuropore during embryogenesis. We thus propose that the cyst arises from the rostral neuropore and that its eventual deep location is explained by the complex morphogenetic movements affecting the dorsal region of the telencephalic vesicle.

Objective: The management of a series of 28 patients operated on for posterior fossa epidermoids is reviewed, emphasizing the need for long-term follow-up. We discuss the rationale for a comprehensive classification system that may allow the comparison of results from homogeneous series., Methods: We grouped the tumors to differentiate the surgical management according to various tumor sites and the degree of extension. Twenty patients harbored tumors located in the cerebellopontine angle, five patients harbored tumors in the fourth ventricle, and three patients harbored tumors in the posterior fossa basal. In 17 patients, extensions of tumors outside the posterior fossa included the following regions: the suprasellar/ chiasmatic (n = 5), the parasellar/temporobasal (n = 5), and the mesencephalic/pineal (n = 7). Tumor extension was also defined by the number of regions involved. Pre- and postoperative magnetic resonance imaging and computed tomographic findings collected in 17 and 28 patients, respectively, were carefully evaluated., Results: Clinical features and surgical approaches varied according to location and growth pattern. Fifty-seven percent of the tumors were completely removed. A higher total removal rate was achieved in patients with tumors confined to the primary location. One patient (3%) died in the perioperative period. Approximately half of the patients presented with transient mild focal deficit impairments resulting from the manipulation of the nervous structure over a wide area. There was a higher rate of surgical complications with fourth ventricle and mesencephalic extended cerebellopontine angle tumors. The mean follow-up period was 8.6 years. Thirty percent of the patients with subtotal removal experienced symptomatic recurrences after 8.1 years, whereas all patients with total removal were still asymptomatic. The recurrence-free survival rate was 95% at 13 years for patients with total removal compared with 65% for patients with subtotal removal. Problems of identification of tumor regrowth are discussed., Conclusion: By assessing posterior fossa epidermoids, we determined that location and extension play a major role in the prognosis. Our data suggest that more aggressive surgery is called for at first operation, and that a second operation should be planned when regrowth becomes symptomatic and/or tends to extend outside its original site.

Objective: Cerebellopontine angle (CPA) epidermoids, although of benign nature, are of considerable neurosurgical interest because of their close proximity and adherence to the cranial nerves and the brain stem. We describe our experience and attempt to correlate the final outcomes with the extent of surgical removal., Methods: Twenty-five consecutive patients with CPA epidermoids that were surgically treated were reviewed, and the final outcomes were assessed., Results: Thirteen patients had trigeminal neuralgia. In 7 of the 13 patients, trigeminal neuralgia was the only presenting feature. The epidermoid was confined to the CPA in each of 6 patients, and in each of 18, it had varying degrees of supratentorial extension. One patient had a predominant supratentorial epidermoid with extension to the CPA. The lesions were totally excised in 12 patients. Near-total removal was accomplished in eight patients, and in the remaining five, partial removal was accomplished. Transient worsening of the cranial nerve functions occurred in 11 patients, probably as a result of aggressive dissection of the capsule from the cranial nerves. In 9 of the 11 patients, the cranial nerve functions improved by the time of discharge. All of the patients who had trigeminal neuralgia were relieved of their symptoms. Eighteen patients were followed up for a mean period of 42 months, and none had symptoms of recurrence., Conclusion: Aggressive surgical removal results in transient but significant cranial nerve dysfunction in the postoperative period. A conservative approach is indicated for patients in whom the capsule is adherent to the brain stem and the cranial nerves.

We present a case of an intradiploic epidermoid cyst with an unusual complication. After a minor fall, a patient with a large right parietal epidermoid suffered a traumatic brain injury caused by the transfer of the force of the fall through the cyst contents to the brain and by transdural herniation of the cyst contents into brain parenchyma. Elective resection of intradiploic epidermoids associated with large bony defects is recommended to avoid this apparently rare but potentially dangerous complication of an otherwise benign condition.

We report on our recent experience with epidermoid cysts in the cerebellopontine angle. We operated on nine patients since 1985, seven of which were investigated with magnetic resonance imaging. Since the arrival of modern neuroimaging, large lesions can be found with only discrete symptoms, such as isolated tinnitus or unspecific headache. With computed tomography and magnetic resonance imaging, preoperative diagnosis was achieved for most patients; sometimes, however, epidermoid cysts may be very similar to arachnoid cysts. Surgery is the only possible treatment. The decision to operate should be carefully discussed for each patient, particularly if the patient is asymptomatic. The extent of the lesion at the anterior aspect of the brain stem, and sometimes above the tentorium cerebelli, fragile cortex, and vessels, and hazards of postoperative chemical meningitis often make such surgery difficult. The surgeon should not attempt total removal of the cyst membrane. Most patients who undergo surgery, however, recover well, with no or few sequelae. With a mean 3-year follow-up, no recurrence occurred, despite partial removal, as a result of the peculiarly slow growth of these lesions.

The case of a 66-year-old man with a 3-year progressive hearing loss and a homogeneous left cerebellopontine angle mass on magnetic resonance imaging scan is described. At surgery, the major portion of the mass was a typical encapsulated, solid, acoustic schwannoma, but the most rostral portion was a distinct, flaky, cystic mass without a well-defined capsule, typical of an epidermoid cyst. The radiographic and operative findings of this unique coexistence of two different benign cerebellopontine angle masses are presented.

Epidermoid tumors occur very rarely in the 4th ventricle. We discuss the history, clinical course, and the surgical results for seven patients. One patient had a remittal of symptoms, probably due to the emergence of the tumor from the 4th ventricle into the cisterna magna. Total removal of the capsule was possible only in the youngest patient. At present, four patients (mean follow-up, 6 years) enjoy good general and neurological health.

Thirteen patients had operations to remove intracranial epidermoid cysts, and long-term follow-up was obtained. Total or nearly total tumor and capsule removal was accomplished in 7 patients during the initial operation. This group required no additional operations. The other 6 underwent subtotal tumor removal and required multiple operations for symptomatic tumor recurrence. This latter group had a poorer neurological outcome. We conclude that initial total or near-total tumor resection is highly desirable in treating intracranial epidermoid cysts, particularly in physiologically young individuals. Five patients were followed after operations to remove pure cholesterol granulomas of the petroclival bone, and 3 additional patients were followed after operations to remove tumors with combined histopathological features of both an epidermoid cyst and cholesterol granuloma. Four patients with some component of a cholesterol granuloma had concurrent middle ear infections, and 4 did not. Intracranial subtotal excision and drainage of these lesions was the initial operative management in 7 patients, 5 of whom have required multiple operations for symptomatic tumor recurrence. Therefore, we conclude that subtotal excisional procedures for tumors with histopathological features of cholesterol granulomas are not usually successful in establishing long-term cures. Total excision, as recommended for epidermoid cysts, tumors frequently confused with cholesterol granulomas when occupying the petroclival region, may be warranted for these tumors as well. We postulate that when a congenital epidermoid cyst occurs in the petroclival bone, it may incite a local inflammatory reaction, producing lesions which have the histological features of both epidermoid cysts and cholesterol granulomas.

Lesions of Meckel's cave are extremely uncommon and difficult to diagnose. The symptoms and signs are variable, and the lesions may not appear on routine roentgenographic or computed tomographic examination. A patient with a small epidermoid tumor of Meckel's cave that was diagnosed by magnetic resonance imaging is herein reported. The epidermoid appeared as a low-intensity mass on the T1-weighted image and as a high-intensity mass on the T2-weighted image. Coronal sections defined the anatomic relationship to the trigeminal nerve. Preoperative recordings of the trigeminal sensory evoked response may be predictive of postoperative recovery of neurological deficits. Furthermore, intraoperative recording was extremely useful in avoiding inadvertent neurological injury. Review of the literature confirms the rarity of this lesion and the usefulness of magnetic resonance imaging in diagnosing it, although based on a limited number of cases.

The authors have treated a 20-year-old man with a dorsal intramedullary epidermoid cyst in whom magnetic resonance imaging was performed both before evacuation of the cyst and 3 months later. Intraspinal epidermoid tumors are rare, and the intramedullary location is quite uncommon. To our knowledge, this is the first description of magnetic resonance imaging of an intramedullary epidermoid cyst. The frequency, possibilities, and limits of surgical treatment of such intraspinal benign tumors are reviewed.

High resolution real time intraoperative ultrasound was used in a number of cases to identify, localize, and characterize intracranial abnormalities. Five case reports illustrate the advantage of this technique during neurosurgical operative procedures.

The clinical features, diagnosis, and management of 23 posterior fossa epidermoid cysts and 9 petrous apex lesions presenting to one unit over a period of 20 years are summarized. Of the epidermoid cysts, 13 were entirely infratentorial, but the other 10 had an additional supratentorial component. Presenting symptoms and signs were usually long-standing and at onset had often been vague and nonspecific. With time, however, a variety of neurological deficits that depended on the site of the lesion developed. These were generally combinations of cerebellopontine (CP) angle and jugular foramen syndromes, deafness, facial palsy, and motor weakness. Diagnostic procedures have changed greatly over the review period. Computed tomography and magnetic resonance imaging have replaced air encephalography and contrast ventriculography. The better preoperative localization of these lesions allows rational planning of the surgical approach required for optimal tumor exposure, which is essential for any attempt at total excision, considering the large size of the majority of these tumors when diagnosed. We favor operation through a posterior fossa craniectomy for those tumors restricted to the CP angle or 4th ventricle, but routinely use a combined supra- and infratentorial approach if the lesion has a more rostral component. The infiltrating nature of epidermoid cysts within the cranium compromises the extent of excision if neurological deficit is not to be increased, but we attempt as complete an excision of tumor and capsule as possible in the hope that many years will pass before symptoms recur. Cholesterol granulomas seem to respond well to simple cavity drainage and have shown no tendency to recur.