On the mechanical behaviour of PEEK and HA cranial implants under impact loading.

The human head can be subjected to numerous impact loadings such as those produced by a fall or during sport activities. These accidents can result in skull fracture and in some complex cases, part of the skull may need to be replaced by a biomedical implant. Even when the skull is not damaged, such accidents can result in brain swelling treated by decompressive craniectomy. Usually, after recovery, the part of the skull that has been removed is replaced by a prosthesis. In such situations, a computational tool able to analyse the choice of prosthesis material depending on the patient's specific activity has the potential to be extremely useful for clinicians. The work proposed here focusses on the development and use of a numerical model for the analysis of cranial implants under impact conditions. In particular, two main biomaterials commonly employed for this kind of prosthesis are polyether-ether-ketone (PEEK) and macroporous hydroxyapatite (HA). In order to study the suitability of these implants, a finite element head model comprising scalp, skull, cerebral falx, cerebrospinal fluid and brain tissues, with a cranial implant replacing part of the skull has been developed from magnetic resonance imaging data. The human tissues and these two biocompatible materials have been independently studied and their constitutive models are provided here. A computational model of the human head under impact loading is then implemented and validated, and a numerical comparison of the mechanical impact response of PEEK and HA implants is presented. This comparison was carried out in terms of the effectiveness of both implants in ensuring structural integrity and preventing traumatic brain injury. The results obtained in this work highlight the need to take into account environmental mechanical considerations to select the optimal implant depending on the specific patient: whereas HA implants present attractive biointegration properties, PEEK implant can potentially be a much more appropriate choice in a demanding mechanical life style. Finally, a novel methodology is proposed to assess the need for further clinical evaluation in case of impact with both implants over a large range of impact conditions.

Colloid cyst in a 12-week-old infant treated with endoscopic third ventriculostomy and cyst fenestration.

We present a case of a colloid cyst in a 12-week-old male infant treated successfully by endoscopic third ventriculostomy and cyst fenestration. To the best of our knowledge, this is the youngest patient in whom such an approach has been utilized and the second youngest with this diagnosis.

Stereotactic radiotherapy for the treatment of neurosarcoidosis involving the pituitary gland and hypothalamus.

We report the case of a 38-year-old, female patient with neurosarcoidosis involving the pituitary gland and hypothalamus, who was treated with stereotactic radiotherapy (24 Gy in 12 fractions) with an excellent result. The purpose of this case report was to illustrate and discuss the diagnostic and therapeutic challenges faced in the management of neurosarcoidosis, as well as document our experience with the use of stereotactic radiotherapy in the treatment of neurosarcoidosis.

The bottom line: outcomes after conservation treatment in anal cancer.

At the Department of Radiation Oncology, Westmead Hospital, between 1980 and 2000, 60 patients with squamous cell carcinoma of anal canal or margin (including 15 with Stage IIIA or IIIB) were treated radically; 55 received chemoradiation (89% were prescribed mitomycin C and 5-fluorouracil). Five-year overall survival was 64% (95% confidence interval (CI): 48-79%), with a median survival of 9.75 years (median follow up 5.6 years, range 5 months to 22.5 years). Ten patients have died of disease. At 2 years the local control rate was 86%, and colostomy-free survival was 83%. Relapse after 2 years was uncommon. Tumour size was the main factor driving outcomes, especially survival. Patients with larger tumours (T > 4 cm) had a hazard ratio for survival of 5.7 (95% CI: 1.8-17). Fourteen (24%) patients experienced treatment interruptions as a result of acute toxicity, including one death from neutropenic sepsis. Seven (12%) patients, in total, experienced one or more late toxicities, grade 3 or above, including four women (all postmenopausal) who developed a radiation-induced bone injury. Most patients with anal cancer can expect to retain a functional sphincter after chemoradiation/radiation. Further studies are in progress to determine the optimal chemoradiation protocol.

Driving and patients with brain tumours: a postal survey of neurosurgeons, neurologists and radiation oncologists.

This study was aimed at evaluating the consistency of driving advice given by treating clinicians to patients diagnosed with brain tumours. Secondary aims include assessing the awareness of current driving guidelines and whether or not there was a need for more specific guidelines in this group of patients. This was undertaken utilizing a scenario-based postal survey. The results show an overall poor consistency in the answers provided for each case scenario. 73.1% respondents were not aware of any current driving guidelines. Of those who were aware of driving guidelines, 67.7% wanted more specific guidelines to be developed. Possible explanations for this are a lack of awareness of the existence of any driving guidelines and a lack of objective criteria in the current driving guidelines. The authors recommend that the current driving guidelines be comprehensively distributed to clinicians who treat patients with brain tumours, as well as forming a multi-disciplinary working party to develop more specific and objective driving guidelines.

Community-acquired methicillin-resistant Staphylococcus aureus brain abscess in an immunocompetent individual.

A 52-y-old woman with a community-acquired methicillin-resistant Staphylococcus aureus brain abscess who was successfully treated with surgical drainage and antibiotics is described. The increase in community-acquired methicillin-resistant S. aureus and the impact this will have on empirical treatment of such infections are discussed.

Naturally occurring PIA/PIB hybrids of Neisseria gonorrhoeae.

The major outer membrane protein of Neisseria gonorrhoeae, Por, functions as a porin and is thought to occur as one gene with two alleles. The immunologically distinct epitopes of the two subclasses, IA and IB, have allowed the development of serotyping schemes. Clinical isolates of N. gonorrhoeae are believed to express only a single type of Por, either IA or IB. We have encountered two clusters of isolates that react with antibodies to both IA and IB Por. Isolates within the clusters are indistinguishable by the phenotypic characteristics tested. In addition, the amplification of the por gene in representative isolates showed that the por gene of the hybrids gave similar restriction digest patterns within but not between the clusters.

Neurotoxic treatment in a patient with brachial neuritis associated with Hodgkin's disease.

Brachial neuritis is a rare form of neuropathy associated with Hodgkin's disease. In the patient we describe, a brachial neuritis occurred during chemotherapy for Hodgkin's disease. He later developed a marked sensory peripheral neuropathy with vincristine. Lhermitte's sign also developed following modest doses of radiotherapy (35 Gy in 20 fractions to the whole cervical cord). We suggest that neurotoxic treatment must be given with extra care to patients with non-metastatic tumour induced neuropathies.