Embedded 3D Printing of Architected Ceramics via Microwave-Activated Polymerization

Light- and ink-based 3D printing methods have vastly expanded the design space and geometric complexity of architected ceramics. However, light-based methods are typically confined to a relatively narrow range of preceramic and particle-laden resins, while ink-based methods are limited in geometric complexity due to layerwise assembly. Here, embedded 3D printing is combined with microwave-activated curing to generate architected ceramics with spatially controlled composition in freeform shapes. Aqueous colloidal inks are printed within a support matrix, rapidly cured via microwave-activated polymerization, and subsequently dried and sintered into dense architectures composed of one or more oxide materials. This integrated manufacturing method opens new avenues for the design and fabrication of complex ceramic architectures with programmed composition, density, and form for myriad applications.

Embedded 3D Printing of Multimaterial Polymer Lattices via Graph-Based Print Path Planning

Recent advances in computational design and 3D printing enable the fabrication of polymer lattices with high strength-to-weight ratio and tailored mechanics. To date, 3D lattices composed of monolithic materials have primarily been constructed due to limitations associated with most commercial 3D printing platforms. Here, freeform fabrication of multi-material polymer lattices via embedded three-dimensional (EMB3D) printing is demonstrated. An algorithm is developed first that generates print paths for each target lattice based on graph theory. The effects of ink rheology on filamentary printing and the effects of the print path on resultant mechanical properties are then investigated. By co-printing multiple materials with different mechanical properties, a broad range of periodic and stochastic lattices with tailored mechanical responses can be realized opening new avenues for constructing architected matter.

Untethered soft robotic matter with passive control of shape morphing and propulsion

There is growing interest in creating untethered soft robotic matter that can repeatedly shape-morph and self-propel in response to external stimuli. Toward this goal, we printed soft robotic matter composed of liquid crystal elastomer (LCE) bilayers with orthogonal director alignment and different nematic-to-isotropic transition temperatures (T _NI) to form active hinges that interconnect polymeric tiles. When heated above their respective actuation temperatures, the printed LCE hinges exhibit a large, reversible bending response. Their actuation response is programmed by varying their chemistry and printed architecture. Through an integrated design and additive manufacturing approach, we created passively controlled, untethered soft robotic matter that adopts task-specific configurations on demand, including a self-twisting origami polyhedron that exhibits three stable configurations and a "rollbot" that assembles into a pentagonal prism and self-rolls in programmed responses to thermal stimuli.

The reliability of prediction of outcome in spina bifida

The clinical findings in 85 neonates with spina bifida were given to two neurosurgeons and two paediatricians, who were asked to predict from them the length of survival and quality of survival with regard to intellect, locomotion and continence, without their knowing the actual outcome. All four clinicians correctly predicted the survival of infants with meningocele, closed myelocele and encephalocele. The paediatricians correctly predicted the survival of all infants with open myelocele who actually survived, but also included some who had died. The surgeons correctly predicted the deaths of all those with open myelocele who actually died, but expected a considerable number to die who in fact survived. All four clinicians were similar in their predictions of intellect: they underestimated the outcome in patients with successfully shunted hydrocephalus, they overestimated the intellect in patients who had developed intracranial infection and shunt blockage, and they largely underestimated the outcome in the patients who did not require shunts. They made correct predictions for limb and sphincter function in nearly all the survivors. This investigation underlines the problem of selection for treatment caused by the inability to predict the complications of hydrocephalus and infection. Reasons for the differences between the expectations of the paediatricians and surgeons, and the implications of the results of this study for selection for surgery are discussed. It is suggested that limb paralysis and incontinence ought not to be considered as factors excluding infants from treatment.

Type I Chiari deformity presenting with profound sinus bradycardia: case report and literature review

Type I Chiari deformity presents with diverse symptoms and signs which can be attributed to compression of structures at the foramen magnum. Bradycardia as a result of medullary compression has not been reported previously. A patient is described with type I Chiari deformity who presented with episodic profound sinus bradycardia for which a pacemaker was inserted before the diagnosis of cerebellar ectopia was finally made. Surgical decompression proved curative.

Twenty-year survival following excision of primary CNS lymphoma without radiation therapy: case report

The prognosis of primary central nervous system lymphoma (PCL) is very poor with a mean survival of 3-6 months without treatment and 15-45 months following radiation therapy. PCL is very sensitive to radiation therapy, but recurrence is frequent. A response of the tumour to steroids has also been documented. This report describes a patient who had surgery for a solitary PCL without subsequent radiation therapy or steroid medication and who had no evidence of tumour recurrence 16 years later. He remains well 20 years after surgery. No case of long-term survival following surgery alone for PCL has been reported previously. Surgical excision may have a place in the management of solitary PCL.

Cortical resections for intractable epilepsy of extratemporal origin: experience with seventeen cases over eleven years

Seventeen patients underwent surgery between 1981 and 1990 for intractable partial epilepsy arising outside the temporal lobe. Twelve had frontal seizure onset, two parietal, two occipital and one diffusely in the hemisphere. Localization was achieved using extraoperative electrocorticography (ECoG) in five cases and intraoperative ECoG was employed in 12. Fifteen patients underwent cortical resections, but two did not subsequently have a resection. Both of these had porencephalic cysts. Of the 15 who had resections six (40%) were seizure free after a mean of 7.3 years. One (7%) was almost seizure free, six (40%) had worthwhile improvement. Pathological examination revealed oligodendroglioma in three, recurrent meningioma in one, vascular malformations in two, glial hamartoma in one and gliosis in six. One case with gliosis initially was shown to have an underlying malignant astrocytoma 2 years later. All these patients had CT abnormalities prior to surgery. Two patients (13%) had no worthwhile improvement. Pathology in these two was ischaemic neurons and arachnoid thickening. Both had normal CT findings preoperatively. One patient had an increased hemiparesis postoperatively. There were three cases of postoperative infection. It is concluded that extratemporal resection can achieve good results for seizure control and intraoperative ECoG is an effective technique for localizing the epileptogenic area. The presence of a structural lesion carries a particularly favourable prognosis for seizure outcome and surgery should, therefore, be strongly considered in patients with intractable partial epilepsy who have evidence of underlying structural pathology.

Temporal lobectomy for intractable epilepsy: experience with 58 cases over 21 years

Sixty patients with intractable complex partial seizures underwent surgery between 1969 and 1990, and 58 of these underwent a temporal resection. Of 39 patients who had chronic subdural electrocorticography (ECoG) 37 subsequently underwent an anterior temporal lobectomy (ATL) and two had the electrodes removed without resection. Two patients had bilateral depth electrodes placed and then had an ATL. Fourteen patients with evidence of temporal structural lesions had temporal resections with intraoperative ECoG and five had resection without ECoG. Mean length of follow-up for all patients was 6 years. Fifty-five per cent of cases were seizure-free postoperatively, 7% almost seizure-free, 21% had worthwhile improvement and 17% no improvement. The outcome for patients with structural lesions was particularly good. Nine patients complained of mild memory impairment postoperatively and one had a severe amnestic problem. One patient with an unsuspected tumour developed a hemiparesis and dysphasia. One other patient had persistent dysphasia. No mortality was attributable to the surgery. It is concluded that ATL is an excellent operation for the treatment of intractable epilepsy arising from the temporal lobe and chronic subdural ECoG is a safe and reliable method for localizing the seizure origin.

Acute spontaneous spinal epidural haematoma with temporary resolution

A case of acute spontaneous spinal epidural haematoma is presented which underwent resolution of symptoms and signs before relapsing again hours later. Cases of spontaneous remission of this condition have been reported but not subsequent relapse. Conservative management of apparently resolving cases may therefore be inappropriate.

Spinal arachnoiditis following subarachnoid haemorrhage

Two cases of chronic adhesive spinal arachnoiditis following documented subarachnoid haemorrhage (SAH) are reported. Both cases progressed to severe spinal cord dysfunction with paraplegia. It is hoped that this case report will highlight this uncommon but extremely disabling complication of SAH.

Dural arteriovenous malformation presenting as cardiac failure in a neonate

Dural arteriovenous malformation (AVM) is a rare clinical entity, presenting most commonly in adult patient with pulsatile tinnitus or haemorrhage. We report a case of a neonate with a massive dural arteriovenous malformation (AVM) with signs of cardiac failure soon after birth. The diagnosis was first suggested during angiocardiography when a hypertrophied left common carotid artery was detected. The AVM was supplied by branches from the left external carotid artery and the left veretebral artery and drained into the left transverse sinus near the torcula. This was excised in two stages. Post-operative angiography showed no residual malformation. The patient was well and developing normally 4 years after surgery. Review of the literature showed only 2 similar cases of dural AVM presenting in the neonatal period, both patients died, reflecting the high risks involved and the difficulties encountered in the management. Ligation of arterial supplies can be a useful temporary procedure in these high risk babies. Definitive excision should be performed later when the baby grows stronger.

Intracranial angiolipoma

Fat containing tumours within the central nervous system are rare. The second reported case of intracranial angiolipoma is described.

Cerebellar haemangioblastoma and von Hippel-Lindau disease

Von Hippel-Lindau disease is an autosomal dominant multisystem disorder, the commonest presenting manifestations of which are haemangioblastomas of the cerebellum and retina. Affected individuals are at risk of developing a number of other lesions, the most serious of which are renal carcinoma, haemangioblastomas elsewhere in the central nervous system and phaeochromocytoma. Patients with this disease can therefore present to a number of disciplines during their lifetime and unless the possibility of von Hippel-Lindau disease is considered, the patient may wrongly be assumed to have an isolated lesion. Twenty patients with cerebellar haemangioblastomas were seen between 1972 and 1985; the diagnosis of von Hippel-Lindau disease was subsequently established in 8. Although the diagnosis had not previously been considered, in retrospect 7/8 cases were known to be at risk of this syndrome. These cases came from 7 families and an additional 4 relatives are also known to have been affected. Mean age of presentation for the various manifestations of von Hippel-Lindau disease, each of which occurred in one or other of our cases, has been calculated from 9 of our patients and 107 others reported in the literature. Clinically significant manifestations almost invariably developed before the age of 50 years. Limited screening of our index cases and their at-risk relatives demonstrated one asymptomatic renal carcinoma. We propose a protocol for screening all individuals at risk of von Hippel-Lindau disease, which involves annual retinal examination from five years, and biennial computerized tomography of the head and abdomen from fifteen and twenty years, respectively.

The functions of the right hemisphere and the brain regions involved in figural matching

A search for the source within the right hemisphere of its primacy on tests of figural matching was made. Patients with right and left hemisphere damage were studied and comparison was made of response to a shape matching task flashed to the right or the left hemisphere. When the right hemisphere is damaged performance seriously declines whether the patient is tested on the right or the left hemisphere. Studies of the specific location within the right hemisphere indicated widespread but subtotal involvement implicating the frontal, temporal and parietal regions of this hemisphere.

Corneal distribution of subconjunctival antibiotics

Radioactive carbon-labeled penicillin G, chloramphenicol, or gentamicin were injected subconjunctivally into rabbit eyes. The distribution of antibiotics throughout the cornea was determined in relation to the injection site; aqueous humor levels were also measured. For chloramphenicol, the highest drug concentrations in the cornea were adjacent to the injection site; levels decreased as the distance from the injection site increased. For penicillin G and gentamicin, highest corneal levels were adjacent to the injection site. Levels were lowest in the central cornea but increased in the peripheral cornea, 180 degrees opposite the injection site. For all antibiotics, therapeutic levels were reached throughout the cornea irrespective of the injection site. Corneal values for all drugs were consistently higher than aqueous humor values. These results suggest that in the treatment of corneal ulcers the choice of subconjunctival injection site is not important.

Herpes simplex encephalitis treated with intravenous idoxuridine

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