Biomedical subjects
Publications and source records attributed to T T King.
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.
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.
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.
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.
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.
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.
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.
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.
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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.
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CT metrizamide cisternography performed in a patient with a non-enhancing cerebellopontine angle tumour demonstrated an increase in attenuation within the cystic area between the immediate scan and that undertaken 4 h later indicating delayed inward diffusion of the contrast. At operation the tumour was found to be a cystic acoustic schwannoma of the cerebellopontine angle. Diffusion of metrizamide was not previously been reported across the wall of a cystic tumour.