[Trigeminal neuromas: modern diagnosis and treatment]. / Trigeminal'nye nevrinomy: sovremennaya diagnostika i lechenie.

Trigeminal neuroma (TN) is a benign neoplasm arising from trigeminal nerve sheath. The tumor can grow from any part of the nerve from the root in posterior cranial fossa to peripheral extracranial branches. Symptoms of trigeminal neuroma are variable and usually depend on location and dimensions of tumor. We present a review devoted to the problem of TN. Surgery was the only possible option in patients with TN for a long time. However, radiotherapy became one of the options and sometimes alternative to surgical treatment since the late 1980s. Besides active management of patients with TN, follow-up with regular radiographic control of small asymptomatic tumors also seems to be reasonable. When evaluating treatment outcomes, physicians consider quality of life and return to previous work and activity in addition to resection quality, neurological impairment, relapse-free period and tumor growth control. However, assessment of these indicators after certain treatment is rare. Thus, it is difficult to determine treatment strategy with maximum ratio of effectiveness and quality of life. Therefore, optimization of TN treatment is currently an urgent problem that requires further study.

Otoacoustic emissions recorded at high rates in patients with confirmed acoustic neuromas.

Otoacoustic emission testing was carried out on 39 patients with confirmed acoustic neuromas, and satisfactory emissions were recorded from the neuroma ear of 59% of them. A comparison of the patients with and without emissions showed no significant differences in low-frequency or high-frequency hearing loss, optimum speech discrimination score, or canal paresis in the affected ear between the two groups. Emissions were recorded at stimulus rates up to 5,000 clicks/s by using the maximum length sequence (MLS) technique. The decrease in the emission amplitude with increase in click rate (rate suppression) was significantly less than the amount that would be expected from normal subjects for several of the neuroma patients. However, one patient showed normal suppression despite having a large neuroma and no measurable hearing. This would suggest that efferent suppression may not be the only mechanism involved.

Normal evoked otoacoustic emissions with a profound hearing loss due to a juvenile pilocytic astrocytoma.

An interesting case is reported of an 11-year-old girl who experienced a sudden, profound right-sided hearing loss at the age of 5 years after hearing a "pop" and the sound of rushing water in her right ear. At that time the patient was thought to have Mondini's deformity, and a perilymphatic fistula of the oval window in the right ear. Six years later she was diagnosed with a juvenile pilocytic astrocytoma of the pons with an exophytic component extending into the cerebellopontine angle. Of particular interest in this case is the presence of evoked otoacoustic emissions in the right ear with a profound neural hearing loss. The presence of transient evoked and distortion product otoacoustic emissions confirmed normal sensory outer hair cell function and an intact peripheral auditory system in a clinically deaf ear, thus indicating hearing loss due to a neural component instead of a sensory component, which was previously assumed.

Direct cochlear nerve action potentials as an aid to hearing preservation in middle fossa acoustic neuroma resection.

A new application of auditory evoked potentials using direct cochlear nerve action potentials (CNAPs) for monitoring middle fossa acoustic neuroma resection with attempted hearing preservation is described. Twenty patients have been studied to date. With this technique, a monitoring electrode is secured between the floor of the internal auditory canal and the dura adjacent to the cochlear nerve in an extradural location. Standard auditory evoked potential techniques with click stimuli and microelectrical recording allow observation of nearfield waveforms in seconds versus several minutes required for farfield potentials recorded from the scalp. Advantages of this technique over auditory brainstem response monitoring may include nearly real time measurement of potentials, improved surgeon learning curve and possibly higher rates of hearing preservation, and applicability to all patients undergoing hearing-preservation surgery independent of presence or absence of ABR tracing. Immediate changes in amplitude and latency of waveforms appear to compare with reversible and irreversible intraoperative auditory system damage, thereby guiding surgical maneuvers.

Gangliogliomas involving the optic chiasm.

We report three patients with gangliogliomas involving the optic chiasm via distinct mechanisms. The ganglioglioma in one patient likely originated in the temporal lobe and spread medially to involve the chiasm, and diffuse spinal cord dissemination also occurred. Chiasmal involvement in this manner and dissemination at presentation are unusual for gangliogliomas. The tumor in a second patient was intrinsic to the hypothalmus and chiasm, while in the third patient, it involved both optic tracts, and a cyst compressed the chiasm laterally. Two patients developed severe bilateral visual loss, while the other had a stable bitemporal hemianopsia. Two patients received radiotherapy, but one continued to lose vision. Although gangliogliomas rarely involve chiasm, the mechanisms by which they produce chiasmal visual loss may be diverse, and the long-term visual prognosis is variable.

Determinants and impact of headache after acoustic neuroma surgery.

Headache after acoustic neuroma surgery is known to occur clinically, but has not been studied systematically until recently. In the present study, 155 patients were surveyed regarding their experience of headache and associated symptoms following resection of an acoustic neuroma: 73 percent (n = 98) of patients undergoing suboccipital resection of an acoustic neuroma and 53 percent (n = 8) of patients undergoing translabyrinthine resection of acoustic neuroma complained of headache following surgery. The average pain intensity was greater for the suboccipital approach. Only 9 percent (n = 14) reported troublesome or frequent headaches preoperatively. Headache was described most often as tension type, with episodic acute exacerbations mimicking migraine. Clinical observations suggest that most patients are treated successfully with various combinations of reassurance, tricyclic antidepressants, nonsteroidal anti-inflammatory medications, trigger-point injections, adjunctive stress management techniques (relaxation), and physical therapy. The impact of recurrent headache on work and recreational function is notable. Several possible pathophysiological and biopsychosocial models are proposed to account for the prevalent headache problem. Although spontaneous resolution usually occurs over time, additional study is needed to determine the natural history of postoperative headache once it occurs.

Surgery of giant gliomas of chiasma and IIIrd ventricle.

During a period of 17 years (from 1976 till now) 45 patients with giant gliomas of the chiasma and the IIIrd ventricle out of a total amount of 120 patients with hypothalamic gliomas were operated. The following classification of tumours was used: I) tumours with predominant anterior growth; II) tumours which infiltrate chiasma and penetrate into the IIIrd ventricle; III) gliomas of the floor of the IIIrd ventricle and the chiasma, growing into the ventricle cavity; IV) tumours of the chiasma, optic tract and thalamus. The authors come to the conclusion, that surgical removal of giant tumours of the chiasma and the IIIrd ventricle, though risk, may result in an improvement or stabilisation of visual functions (77%) and a long period free from recurrencies (9.5%). The postoperative period is relatively favourable and the mortality is low (6%). The main contraindication in our opinion is a wide infiltration of adjacent brain structures by the tumour and spreading along both optical tracts. We consider the giant size of a tumour in itself a sufficient indication for surgery.

Thyroplasty in the functional rehabilitation of neurotologic skull base surgery patients.

Definitive management of lesions of the lateral cranial base is surgical. Functional outcome is dependent on cranial nerve preservation. In 1988 an effort was made to decrease the incidence of tracheotomy, the duration of hospital stay, and the period prior to unassisted oral intake, by establishing more immediate acquisition of glottic competence through laryngeal rehabilitation. The experience of one author (JLN) in over 40 phonosurgical procedures under local anesthesia is presented. Although tracheotomy provides excellent airway protection, it is accompanied by substantial morbidity. The technique of phonosurgery has dramatically improved recovery and functional outcomes of neurotologic skull base surgery patients, enabling them to realize "cure" rather than "control" of their disease.

Vascular malformation with radiation vasculopathy after treatment of chiasmatic/hypothalamic glioma.

Chiasmatic/hypothalamic gliomas usually are histologically benign astrocytomas that may recur many years after diagnosis and treatment. Three children with chiasmatic/hypothalamic gliomas who were treated at the authors' institution returned 9.5, 11.5, and 2 years, respectively, after radiation therapy (RT) because visual and neurologic deterioration developed. Neuroradiographic studies, including arteriography in two of the patients, showed large mass lesions. These were presumed to be recurrence of tumor, and chemotherapy was administered. Pathologic examination of two children who died and of the third who had a biopsy revealed only a minimal amount of residual, histologically benign astrocytoma, whereas the bulk of the specimen consisted of numerous vessels of variable size. These probably represented incorporation of the rich vasculature in the chiasmal region into the tumor, which underwent degeneration secondary to RT. Radiographic methods did not distinguish progressive tumor growth from the vasculopathy and led to inappropriate clinical diagnoses and treatment.

Pathology of midline brain tumors. Immunocytochemical tumor markers and classificatory aspects.

Our understanding of the pathology of human brain tumors has considerably increased in recent years thanks to investigation of nervous tissue markers which can be demonstrated by immunocytochemical techniques in sections of neurosurgical tissue specimens. This development is presented here in a review of the most important entities among midline brain tumors. Detection of neural differentiation markers such as glial fibrillary acidic protein (GFAP), S 100 protein (S 100 p), neurofibrillary proteins and neuron-specific enolase (NSE) greatly contributed to clarifying the histogenesis and differentiation potential of undifferentiated small-cell tumors grouped as primitive neuroectodermal tumors (PNETs) which include cerebellar medulloblastomas and pinealoblastomas as well as neuroblastomas and ependymoblastomas. Among medulloblastomas, the desmoplastic variety (formerly called by some "arachnoidal sarcoma of the cerebellum") shows frequent glioneuronal differentiation. Monoclonal antibodies recognizing antigenic determinants specific for tumor types and grades of malignancy/differentiation will gain significance in brain tumor diagnosis, as demonstrated in some examples. Despite the development of more objective ("scientific") criteria for typing human brain tumors, the "art" of classical histopathologic evaluation is not replaced but supplemented by the wealth of data supplied by such modern accomplishments.

Large hypothalamic and optic chiasm gliomas in infants: difficulties in distinction.

Hypothalamic and optic chiasm gliomas may be indistinguishable clinically, radiographically, and pathologically. Ten children with giant gliomas of the hypothalamus and optic pathway, all under age 2 years, had masses greater than 3 cm in diameter. Pathologically all proven cases (seven) were cytologically benign fibrillary astrocytomas. Previous authors have recognized the difficulty in distinguishing these lesions; in this series, using previously suggested criteria, masses of optic chiasm could not be differentiated from hypothalamic origins. Likewise, at surgery and autopsy, the origin of these large masses was indeterminate. These tumors were more aggressive, invasive, and less responsive to therapy than the relatively benign orbital and optic nerve gliomas of older children and adults.

Chiasmatic and hypothalamic extension of optic nerve glioma.

An 11-year-old boy was found to have a left optic nerve glioma confined to the orbit and optic canal by clinical examination and computed tomographic (CT) scanning. Repeated neuroradiologic examinations demonstrated intracranial extension of tumor to involve the hypothalamus and third ventricle. Following craniotomy and verification of the diagnosis of glioma by biopsy, the patient underwent a course of radiotherapy that resulted in marked tumor regression. The potential for growth of optic nerve gliomas mandates careful neuroradiologic follow-up regardless of whether there is ophthalmologic deterioration. The natural history of "optic gliomas" remains unknown.

[Optic chiasm gliomas (author's transl)]. / Gliomes opto-chiasmatiques.

A follow up study of 40 cases of optic chiasm gliomas is presented. Histological examination was obtained in 26 cases. All were bipolar spongioblastomas. Four of these were optic nerve gliomas, 17 chiasmatic gliomas and 19 invasive optohypothalamic tumors. The main clinical features are reviewed with special attention to endocrine disorders, including precocious puberty and diencephalic emaciation. Neurofibromatosis was present in 30%. Diagnostic difficulties are outlined, especially in chiasmatic tumors without optic nerve involvement: event with C T scan, the differential diagnosis with ectopic pinealomas, craniopharyngiomas and primary hypothalamic tumors, may be difficult. The operative mortality was 12% (3/25). All but one, had radiotherapy either alone or post operative. All four of the patients with unilateral optic nerve gliomas have a normal C T scan more than 10 years after treatment. Of the 17 patients with chiasmatic gliomas, 14 are alive with normal C T scan in 2 cases, and with reduction in size of the tumor in 7. Eleven of 19 patients with invasive gliomas are alive with diminished size of the tumor in 7. Improvement in visual acuity, reduction in size of tumor mass, persistent increase in size of non irradiated tumor and lack of recurrence of optic nerve glioma even with histological proven chiasmatic involvement is taken as evidence of the effect of radiotherapy. The sub frontal approach is emphasized for optic nerve and optic chiasm tumors: it provides direct surgical verification with the opportunity for complete removal, large biopsy, decompression of the optic foramina or cyst removal. Regarding secondary endocrine disorders, radiotherapy is discussed in children. If necessary it must be managed under careful evaluation of endocrine status, principally growth function.