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Half-lifes (T1/2) of exotic neutron-rich isotopes of Ba, La, Ce, Pr, and Nd were measured at the RIKEN Nishina Center. The experimental setup consisted of the BigRIPS in-flight separator for ion selection identification, the Advance Implantation Detector Array (AIDA) for ions and β detection, and the BRIKEN detector for neutron counting. Using this setup, 4 new T1/2 have been measured for the first time, and 38 T1/2 have been remeasured with improved precision in several cases. These new experimental data should help to constrain theoretical models for calculations of T1/2. The status of the experimental analysis and preliminary results are provided in this contribution.

At the RIKEN Nishina Center, exotic neutron-rich isotopes of Ba, La, Ce, Pr, and Nd were measured. This work reports their half-lives (T1/2) and β-delayed neutron-emission probabilities (Pxn). The setup consisted of the BigRIPS in-flight separator for particle identification, the Advanced Implantation Detector Array (AIDA) for ions and β detection, and the BRIKEN neutron counter for neutron detection. Using this arrangement, 4 new T1/2 and 14 new P1n were measured. Furthermore, 38 T1/2 and 2 P1n values were remeasured, decreasing the uncertainties for some of them. In addition to improving predictions of nucleosynthesis models that describe the production of the rare-earth peak at A ∼ 160 via the r-process, these additional experimental data should help to constrain theoretical models for calculations of T1/2 and Pxn in this region.

Abstract Intraventricular craniopharyngiomas are rare tumours. They are wholly within the third ventricle and can be distinguished from suprasellar lesions which extend into the third ventricle by the presence of an intact floor of the third ventricle. They are attached to the wall of the third ventricle to a variable extent, most commonly in the region of the tuber cinereum. The long-term follow-up on six cases treated by one of the authors is presented. Headache and visual disturbance were the most common presenting features but, unlike the more common suprasellar lesions, symptomatic endocrine disturbances were not a common presenting feature. Total surgical removal can cause hypothalamic damage and the resulting morbidity can be serious and sometimes life-threatening. Subtotal removal followed by radiotherapy is probably the treatment of choice for these lesions. [ABSTRACT FROM AUTHOR]

One-hundred-and-fifty-two patients who underwent surgery for intracranial aneurysm were studied to determine the incidence of postoperative epilepsy in relation to the site of the aneurysm and the type of surgical approach. The overall incidence of epilepsy was 22%. Of the 116 patients treated by the intracranial approach 27.5% developed epilepsy, in contrast with only 5% of the 36 patients who had carotid artery ligation in the neck. Epilepsy occurred most frequently (35%) with middle cerebral artery aneurysms, especially if moderate or severe operative trauma was sustained and there was postoperative dysphasia. [ABSTRACT FROM AUTHOR]

Sixty-nine patients who had neurosurgical treatment for acoustic neuroma by one of two different techniques were studied with a view to determining the incidence of postoperative epilepsy. Fourty-five patients who had larger tumours underwent a combined translabyrinthine and transtentorial neurosurgical approach. For the others with smaller neuromas a translabyrinthine method was used. Only the combined approach was associated with postoperative epilepsy, and it occurred in 22% of the patients. Epilepsy was associated with temporal love trauma during surgery. [ABSTRACT FROM AUTHOR]

We investigated decays of ^{51,52,53}K at the ISOLDE Decay Station at CERN in order to understand the mechanism of the β-delayed neutron-emission (βn) process. The experiment quantified neutron and γ-ray emission paths for each precursor. We used this information to test the hypothesis, first formulated by Bohr in 1939, that neutrons in the βn process originate from the structureless "compound nucleus." The data are consistent with this postulate for most of the observed decay paths. The agreement, however, is surprising because the compound-nucleus stage should not be achieved in the studied β decay due to insufficient excitation energy and level densities in the neutron emitter. In the ^{53}K βn decay, we found a preferential population of the first excited state in ^{52}Ca that contradicted Bohr's hypothesis. The latter was interpreted as evidence for direct neutron emission sensitive to the structure of the neutron-unbound state. We propose that the observed nonstatistical neutron emission proceeds through the coupling with nearby doorway states that have large neutron-emission probabilities. The appearance of "compound-nucleus" decay is caused by the aggregated small contributions of multiple doorway states at higher excitation energy.

The first complete measurement of the β-decay strength distribution of _{17}^{45}Cl_{28} was performed at the Facility for Rare Isotope Beams (FRIB) with the FRIB Decay Station Initiator during the second FRIB experiment. The measurement involved the detection of neutrons and γ rays in two focal planes of the FRIB Decay Station Initiator in a single experiment for the first time. This enabled an analytical consistency in extracting the β-decay strength distribution over the large range of excitation energies, including neutron unbound states. We observe a rapid increase in the β-decay strength distribution above the neutron separation energy in _{18}^{45}Ar_{27}. This was interpreted to be caused by the transitioning of neutrons into protons excited across the Z=20 shell gap. The SDPF-MU interaction with reduced shell gap best reproduced the data. The measurement demonstrates a new approach that is sensitive to the proton shell gap in neutron rich nuclei according to SDPF-MU calculations.

The β decays from both the ground state and a long-lived isomer of ^{133}In were studied at the ISOLDE Decay Station (IDS). With a hybrid detection system sensitive to β, γ, and neutron spectroscopy, the comparative partial half-lives (logft) have been measured for all their dominant β-decay channels for the first time, including a low-energy Gamow-Teller transition and several first-forbidden (FF) transitions. Uniquely for such a heavy neutron-rich nucleus, their β decays selectively populate only a few isolated neutron unbound states in ^{133}Sn. Precise energy and branching-ratio measurements of those resonances allow us to benchmark β-decay theories at an unprecedented level in this region of the nuclear chart. The results show good agreement with the newly developed large-scale shell model (LSSM) calculations. The experimental findings establish an archetype for the β decay of neutron-rich nuclei southeast of ^{132}Sn and will serve as a guide for future theoretical development aiming to describe accurately the key β decays in the rapid-neutron capture (r-) process.

Excited-state spectroscopy from the first experiment at the Facility for Rare Isotope Beams (FRIB) is reported. A 24(2)-μs isomer was observed with the FRIB Decay Station initiator (FDSi) through a cascade of 224- and 401-keV γ rays in coincidence with ^{32}Na nuclei. This is the only known microsecond isomer (1  μs≤T&#95;{1/2}<1  ms) in the region. This nucleus is at the heart of the N=20 island of shape inversion and is at the crossroads of the spherical shell-model, deformed shell-model, and ab initio theories. It can be represented as the coupling of a proton hole and neutron particle to ^{32}Mg, ^{32}Mg+π^{-1}+ν^{+1}. This odd-odd coupling and isomer formation provides a sensitive measure of the underlying shape degrees of freedom of ^{32}Mg, where the onset of spherical-to-deformed shape inversion begins with a low-lying deformed 2^{+} state at 885 keV and a low-lying shape-coexisting 0&#95;{2}^{+} state at 1058 keV. We suggest two possible explanations for the 625-keV isomer in ^{32}Na: a 6^{-} spherical shape isomer that decays by E2 or a 0^{+} deformed spin isomer that decays by M2. The present results and calculations are most consistent with the latter, indicating that the low-lying states are dominated by deformation.

New half-lives for exotic isotopes approaching the neutron drip-line in the vicinity of N∼28 for Z=12-15 were measured at the Facility for Rare Isotope Beams (FRIB) with the FRIB decay station initiator. The first experimental results are compared to the latest quasiparticle random phase approximation and shell-model calculations. Overall, the measured half-lives are consistent with the available theoretical descriptions and suggest a well-developed region of deformation below ^{48}Ca in the N=28 isotones. The erosion of the Z=14 subshell closure in Si is experimentally confirmed at N=28, and a reduction in the ^{38}Mg half-life is observed as compared with its isotopic neighbors, which does not seem to be predicted well based on the decay energy and deformation trends. This highlights the need for both additional data in this very exotic region, and for more advanced theoretical efforts.

Two cases are presented in which patients flying home shortly after translabyrinthine removal of a vestibular schwannoma (acoustic neuroma) developed acute bacterial meningitis on landing. This complication has not been described before. The incidence and management of CSF leaks after vestibular schwannoma surgery is also discussed.

A retrospective study of the surgical management of 41 cerebellopontine angle (CPA) meningiomas was performed. All patients were treated by a single surgeon (TTK) over a 25 year period (1967-1992). There were 13 males, 28 females with a median age of 53.5 years. The median follow-up after surgery was 9 years (range 2-20.4 years). Tumours were classified anatomically into six groups (lateral, midpetrosal, petroclival, internal auditory meatal, Meckel's cave and inferior). Only the petroclival tumours posed difficulties with complete resection (achieved in 7 out of 16) and for most of them a transtentorial transpetrous approach was used. In other groups, complete resection was achieved in all patients. There were four recurrences (two mid-petrosal, one petroclival, one internal auditory meatal), three of which had complete macroscopic resection at the initial operation.

Five cerebellopontine angle tumors from four patients with neurofibromatosis (NF) are described. Three were surgical resection specimens from patients with NF2 and two were removed at autopsy from a fourth patient who appears to have had a variant of NF2. On microscopy the three biopsy specimens appeared to be histologically mixed tumors: although they were predominantly typical benign schwannomas, the tumors also contained islands of meningioma, the two tumor types being closely intermingled. In our fourth patient, consecutive decalcified sections of the tumors in the petrous temporal bones revealed florid arachnoidal proliferation around both schwannomas. This had resulted in the formation of multiple "micromeningiomas", some of which had become partially incorporated into the tumor. There are a few previously reported examples of mixed schwannoma-meningiomas in the literature. Possible mechanisms for such a mixed tumor are discussed: the most likely explanation for the appearances in cases of apparently mixed vestibular nerve tumors is that reactive meningeal changes adjacent to the tumor are responsible. Arachnoidal proliferation appears to be more exuberant in bilateral acoustic neurofibromatosis than in sporadic acoustic schwannomas, possibly the result of a disease-related growth factor.

We reviewed presentation, diagnostic problems and outcome of eight cases of primary intracranial germ-cell tumour (4 germinoma, 4 teratoma) treated with Cisplatin-based chemotherapy at our centre over the last ten years. Three patients received primary chemotherapy with Cisplatin-based regimens followed by radiotherapy for subsequent relapse, two were treated with a combination of chemotherapy and external radiotherapy, and three received chemotherapy for relapse after radiotherapy. The response to Cisplatin-based chemotherapy was rapid, with some patents exhibiting symptomatic improvement within 24 h. Four patients achieved complete remission within 21 days, and three of these have remained progression-free. Four patients in total have survived for 32 to 128+ months. Six of seven patients tested pre-treatment had central diabetes insipidus and five had partial anterior pituitary failure. The endocrine deficit progressed in two, with no recovery in any patient. It is arguable that chemotherapy should be the primary therapy in all such cases diagnosed on the basis of tumour markers and imaging, with surgery and/or radiotherapy as later options. As these tumours are rare, such questions can only be answered by collaboration studies.

The results of repair of 18 facial nerves were examined by means of a modified House-Brackmann grading system. Six were repaired by end-to-end anastomosis and 12 by nerve graft. The reliability of the simplified House-Brackmann grading system was also assessed, using the kappa statistic to analyze the agreement between pairs of observers who examined the function of 40 nerves in 37 patients. Facial nerves studied had been either preserved, repaired or grafted, or divided and treated by faciohypoglossal nerve anastomosis. One nerve was not treated. The grading system proved to be somewhat unreliable, with complete agreement between observers in only 25% of cases. Facial nerve repair produced a fair return of function in just under two-thirds of the cases. The ability of an examiner ignorant of the patient's history to assess from the end result how the nerve had been managed was also estimated. Observers showed little ability to decide correctly on the previous treatment of the nerve when the patient showed moderate dysfunction postoperatively. The implications of these findings for grading systems and for management of the facial nerve in acoustic nerve tumor surgery are discussed.

The results of a U.K. study of 145 cases of type 2 neurofibromatosis has shown generally very poor operative results in terms of hearing and facial nerve preservation. Only 9 out of 118 vestibular schwannoma (acoustic neuroma) operations resulted in any clinically detectable hearing preservation and only 32 left the patient with good or normal (House grade I or II) ipsilateral facial nerve function. Although operation is still the definitive treatment of vestibular schwannoma (acoustic neuroma) and may be a lifesaving procedure, it appears that the evidence in favour of early operation is only valid when carried out in highly specialized centres. The special problems of NF2 cases who may go on to develop multiple spinal and cranial tumours making them wheelchair bound and blind as well as deaf warrants a careful experienced approach. Timing of operations may be critical for the enhancement of useful years of quality life. We therefore propose the setting up of a national NF2 register, with the management of cases at a few supraregional centres.

Although selective transsphenoidal surgery is an effective treatment for pituitary-dependent Cushing's syndrome the definition of cure as distinct from improvement is unclear. Complete tumor removal should be associated with very low serum cortisol levels because of long-term suppression of normal corticotrophs but the optimum timing of this investigation after surgery has not been established. Eleven consecutive patients with surgical and histological confirmation of a corticotroph adenoma removed at transsphenoidal surgery for proven Cushing's disease were studied with 0900 h serum cortisol levels at 5-14 days and 6-12 weeks postoperatively. Patients were maintained on hydrocortisone 10 mg three times daily (final dose at 1800 h) pending recovery of the hypothalamic-pituitary axis which was assessed by periodic short tetracosactrin tests and continued remission of the condition was confirmed by low dose dexamethasone suppression testing. All patients achieved clinical resolution of their disease but four subsequently developed biochemical evidence of recurrence with incomplete suppression on low dose dexamethasone testing at 2-48 months after surgery. These patients had 0900 h serum cortisol levels of 124, 95, 186, and 265 nmol/L at 5-14 days and 334, 52, 130, and 240 nmol/L at 6-12 weeks postoperatively. The remaining seven patients, who are in remission after 8-83 (median 24) months of follow-up, demonstrated 0900 h serum cortisol levels of 30-75 (median 31) nmol/L at 5-14 days but lower levels at 6-12 weeks (< 20 nmol/L in three patients and 22, 30, 30, and 33 nmol/L in the remainder). In this series, serum cortisol measurements at 6-12 weeks after transsphenoidal surgery for Cushing's disease are lower than levels obtained within 2 weeks of surgery and appear to give better discrimination of continuing remission; levels less than 35 nmol/L suggest a favorable long-term outcome.

Neurovascular decompression is a widely practiced technique for the treatment of trigeminal neuralgia, and yet there is still debate as to whether the beneficial effect results from relieving the nerve of compression by an anatomically abnormal vessel or from the manipulation and trauma the nerve undergoes during the procedure. The development of this operation has been hampered by the lack of adequate anatomical studies in normal controls. The authors present a combined study of clinical and anatomical material employing standardized definitions of the neurovascular relationships in both groups. Detailed simulations of the operative procedure were carried out on fresh cadavers matched for age, sex, and side, and a technique of in situ blood vessel perfusion was developed that enabled the normal neurovascular arrangement to be observed post mortem at physiological pressures. Neurovascular compression, typified by a large vessel distorting and creating a groove in the fifth cranial nerve, was found in 37 of the 41 cases of trigeminal neuralgia; recurrence of pain did not relate to the site of compression. A follow-up study was carried out for a median of 53 months (range 12 to 103 months). No distortion was found in a total of 50 normal cadaveric dissections; however, on perfusion to physiological pressures, the percentage of nerves with vessels adjacent or in simple contact increased from 16% to 40%. This study using this new technique confirms that vascular compression of the fifth cranial nerve is an anatomical abnormality specific to trigeminal neuralgia.

In a series of over 500 cases of cerebellopontine angle tumors, 19 patients had bilateral neurinomas. Four of these tumors arose from the facial rather than the acoustic nerve. A conservative policy regarding surgery had been adopted in an effort to prevent hearing loss for as long as possible. Nevertheless, all patients operated on in this series are now totally deaf. The results of managing these patients surgically and conservatively are discussed.

A case of lateral prolapse of the T-1/T-2 intervertebral disk is presented. The patient complained of pain radiating down the medial aspect of the forearm into the little and ring fingers. This was associated with a subjective sensory loss in the same distribution, intact reflexes, and no long tract signs. Oculosympathetic paralysis was not present. Twelve cases have been mentioned in the literature, only eight of which contain details of the neurological findings. The varied findings in these cases are also reviewed, and it is noted that unless radiological examination includes the upper thoracic spine in cases of brachial neuralgia, these lesions will be missed.

Dural spinal arteriovenous malformations are increasingly recognized as a rare but treatable cause of progressive paraplegia, but the clinical picture, especially in early cases, is not easy to recognize and operation may therefore be delayed until considerable loss of function has occurred. We present a series of seven cases which illustrate the characteristics and diagnostic difficulties of this condition.

An increasing number of patients with an acoustic neuroma present with useful hearing in the tumour ear. Surgical removal of these tumours via the posterior fossa route may enable preservation of the cochlear nerve and otic capsule without increasing the morbidity to the facial nerve. The results of treating 51 cases of acoustic neuroma via the posterior fossa is presented. Forty four tumours measured less than 20 mm in diameter in the cerebellopontine angle and surgery was undertaken with hearing preservation as a principle objective. In 26 cases, the cochlear nerve was preserved anatomically and post-operative hearing at levels better than mean pure tone threshold of 50 dB or 50 per cent speech discrimination was recorded in 14 patients. The preservation of hearing represents a worthwhile surgical goal in selected patients with an acoustic neuroma without increasing the operative morbidity.

In a series of 527 cerebellopontine angle tumors, there were 416 cases of acoustic nerve tumors and 14 cases of primary tumor of the facial nerve in the petrous bone or intracranial cavity. Six additional patients were presumed to have facial tumors, although they were not operated on. Of the 14 verified facial nerve tumors, all but two were neurinomas and 11 had important intracranial extensions into the middle and/or the posterior fossa. In most of these 14 cases, surgical removal was performed via the translabyrinthine route, which is advantageous in that it displays the characteristic relationship of the tumor to the facial nerve, and facilitates nerve repair. The clinical and radiological features of these facial nerve lesions are discussed and also the indications for surgical treatment which, as the unoperated cases illustrate, is not always necessary.

The authors present a case of an intraventricular 14-cm fetus in a 6-week-old infant who presented with enlarging head size. The entire intracranial fetus, with recognizable limbs, trunk, head, and exomphalos, was removed totally from the lateral and third ventricles, with excellent recovery in the patient, who is now 18 months old. The cytogenetical and tissue histological studies are reported. The embryology, operative procedure, and pathology of this condition are discussed and the literature briefly reviewed.

The translabyrinthine route or an extension of it was used to remove 150 acoustic nerve tumors. The mortality was 2% and the morbidity low. Preservation of the facial nerve was achieved in 100% of the small and 80% of the medium-sized tumors, but in only 20% of the large growths. The complications encountered are discussed.

Cystic lesions in the petrous apex are nearly always either epidermoid cysts, with a soft but solid content, or cholesterol cysts, containing brown fluid. They may be symptomless, produce progressive cranial nerve palsies or, occasionally, reach the CSF pathways thus leading either to meningitis or a CSF leak. Thirteen cases and four unverified cases have been encountered amongst a series of more than 500 cerebellopontine angle tumours. Their clinical features, radiological diagnosis and difficulties of surgical approach are discussed.

A critical account is given of the orthodox neurosurgical approach to acoustic nerve tumours and alternatives through the petrous bone or tentorium.