Dumbbell-shaped jugular foramen schwannoma

Importance of preserved periosteum around jugular foramen neurinomas for functional outcome of lower cranial nerves: anatomic and clinical studies

BACKGROUND

Surgical removal of jugular foramen (JF) neurinomas remains controversial because of their radicality in relation to periosteal sheath structures.

OBJECTIVE

To clarify the particular meningeal structures of the JF with the aim of helping to eliminate surgical complications of the lower cranial nerves (LCNs).

METHODS

We sectioned 6 JFs and examined histological sections using Masson trichrome stain. A consecutive series of 25 patients with JF neurinomas was also analyzed, and the MIB-1 index of each excised tumor was determined.

RESULTS

In the JF, meningeal dura disappeared at the nerve entrance, forming a jugular pocket. JF neurinomas were classified into 4 types: subarachnoid (type A by the Samii classification), foraminal (type B), epidural (type C), and episubdural (type D). After an average follow-up of 9.2 years, tumors recurred in 9 cases (36%). Type A tumors did not show regrowth, unlike type B tumors, in which all recurred. Radical surgery by the modified Fisch approach did not contribute to tumor radicality in type C and D tumors, even in cases in which LCN function was sacrificed. In preserved periosteum, postoperative LCN deterioration was decreased. Bivariate correlation analysis revealed that jugular pocket extension, tumor removal, MIB-1 greater than 3%, and reoperation or gamma knife use were significant recurrence factors.

CONCLUSION

For LCN preservation, the periosteal layer covering the cranial nerves must be left intact except in patients with a subarachnoid tumor. To prevent tumor regrowth, postoperative gamma knife treatment is recommended in tumors with an MIB-1 greater than 3%.

Severe progressive sensorineural hearing loss improved after removal of large jugular foramen schwannoma

We report a very rare case of hearing improvement after removal of the intracranial part of a jugular foramen schwannoma (JFS) presenting with chronic and severe progressive sensorineural hearing loss (SNHL). The patient presented with progressive hearing impairment in his right ear, lasting 2 years. The patient's pure tone audiogram revealed severe SNHL. His speech discrimination score (SDS) was 0%. Auditory-evoked brain responses (ABRs) comprised only I waves following 30-100dB stimulation, although distortion-product otoacoustic emissions (DPOAEs) had good responses. These test results indicated that his hearing impairment was retrocochlear SNHL. Magnetic resonance imaging revealed within the right jugular foramen a large intracranial-extracranial tumor that compressed the brainstem. The intracranial part of the tumor was resected through retrosigmoidal craniotomy, and the tumor was pathologically diagnosed as a schwannoma. Several months after the operation, the patient's auditory thresholds improved to a level consistent with mild SNHL, ABR V waves emerged following 60-90dB stimulation, and SDS improved significantly to 95%. This case demonstrates that hearing improvement can be achieved after surgery for JFS presenting with severe and chronic progressive SNHL, and that good DPOAE responses and the presence of ABR I waves may be predictors of postoperative hearing recovery in JFS.

Microsurgical management of 53 jugular foramen schwannomas: lessons learned incorporated into a modified grading system

OBJECT

Due to the proximity and involvement of critical neurovascular structures, the resection of jugular foramen schwannomas can pose a formidable challenge. The authors review their experience in the microsurgical management of jugular foramen schwannomas and propose a modified grading scale to guide surgical management.

METHODS

All jugular foramen schwannoma cases treated by the senior author (T.F.) between 1980 and 2004 were retrospectively reviewed. The average age at presentation, surgical approach, tumor characteristics, cranial nerve (CN) deficits, and tumor recurrence rates were assessed. The authors present the following modified grading scale: Type A, intradural tumors; Type B, dumbbell-shaped tumors; and Type C, triple dumbbell tumors with a high cervical extension.

RESULTS

The authors treated jugular foramen tumors in 129 patients during the study period. Of these, 53 patients (41%) had jugular foramen schwannomas. The mean patient age was 52 years (range 14-74 years); there were 12 male and 41 female patients. The mean follow-up period was 8.4 years. Patients presented most commonly with deficits of the vagus nerve, followed by vestibular/cochlear nerve and glossopharyngeal nerve deficits. Gross-total resection of the tumor was achieved in 48 patients (90.5%). New postoperative paresis in a previously normal CN was not seen; however, worsening of preoperative CN deficits was frequently noted. The highest incidence occurred with the glossopharyngeal and vagus nerves (30%), with 26% of the deficits being permanent. There were no deaths related to surgery in this series. Three patients (5.7%) experienced tumor recurrence.

CONCLUSIONS

The microsurgical resection of jugular foramen schwannomas carries a risk of worsening preoperative CN deficits; however, these are often transient. Based on their experience, the authors have formulated a grading scale that predicts the optimal surgical approach to these lesions. Considerable technical training and microneuroanatomical knowledge of the region is required. The modified grading scale presented facilitates preoperative planning.

Reversible cochleo-vestibular deficits in two cases of jugular foramen tumor after surgery

Primary jugular foramen (JF) tumor, such as glomus jugular tumor or JF schwannoma, may manifest as a lower cranial nerve deficit; in addition, it can be accompanied by deafness or vertigo if it affects the cranial nerve (CN) VIII. Recently, we encountered JF schwannoma 1 and glomus jugulare tumor 1. Both cases invaded the adjacent cerebellopontine angle, leading to cochleo-vestibular deficits prior to the operation. After surgery, recovery of the audiovestibular function, including hearing, auditory brainstem response and caloric response, was anticipated in both patients. Therefore, cochleo-vestibular deficits in JF tumors can be attributed to compression neuropathy, rather than tumor infiltration.

Recovery of audition after favorable resection of vagal schwannoma

Two patients with vagal schwannoma manifesting as deafness with no lower cranial nerve paresis were treated surgically. A 42-year-old male underwent partial resection of the tumor, which was tightly adhered to the cranial nerves, to prevent lower cranial nerve paresis. A 29-year-old female underwent total removal of the tumor without complications. The patients recovered useful audition with no postoperative deficit.

Surgical tactics and outcome of treatment in jugular foramen schwannomas

Seven patients with schwannomas of the jugular foramen were included our study in Samsung Medical Center between 1995 and 1999. Patients with neurofibromatosis were excluded. The records of the seven patients (six surgical case and one nonsurgical case) were retrospectively reviewed. There were six women and one man (mean age, 47 years) with a symptom duration ranging from 3 months to 14 years (mean, 47 months). The predominant symptoms were hearing difficulty, hemifacial spasm and hoarseness. Preoperative audiologic evaluation, computerised tomography (CT), magnetic resonance (MR) imaging, and angiography were performed in most patients. We classified tumours into four types using Kaye and Pellet classification on the basis of radiological and surgical findings. The tumours were: Type A (at cerebellopontine angle) in one; Type B (foraminal) in two; Type C (extracranial and/or foraminal) in two; and Type D (intra- and extracranial) in two cases. We used various surgical approaches such as retrosigmoid suboccipital craniectomy for Type A tumours, infratemporal fossa type A approach (ITFA) for Type C tumours, petro-occipital transsigmoid approach or modified transcochear approach for Type D tumours and ITFA with partial labyrinthectomy for Type B. In the selection of surgical approaches, we took consideration of tumour extension, tumour size, and preoperative hearing function. Facial nerve transposition was not used only in one case of ITFA because of small tumour size (1.5cm). Gross total removal was achieved in five cases, and subtotal removal in one case (Type D tumour) with a single-stage operation. Stereotactic radiosurgery was performed on residual mass in the subtotally removed case. Follow-up period ranged from 13 to 49 months (mean, 27.5 months). There was neither postoperative mortality nor recurrence on follow-up MR imaging. There were two cases of temporary facial nerve palsy and one aggravation of pre-existing low cranial palsy. Two case of sustained vocal cord palsy underwent thyroplasty, but there was no aspiration pneumonia. Persistent cerebrospinal fluid collection was improved with lumboperitoneal shunt. The surgical approaches of each case should be tailored according to their shape and the clinical manifestation. We obtain acceptable outcomes from one-stage operation.