Vertebroplasty reduces progressive ׳creep' deformity of fractured vertebrae.

Elderly vertebrae frequently develop an "anterior wedge" deformity as a result of fracture and creep mechanisms. Injecting cement into a damaged vertebral body (vertebroplasty) is known to help restore its shape and stiffness. We now hypothesise that vertebroplasty is also effective in reducing subsequent creep deformations. Twenty-eight spine specimens, comprising three complete vertebrae and the intervening discs, were obtained from cadavers aged 67-92 years. Each specimen was subjected to increasingly-severe compressive loading until one of its vertebrae was fractured, and the damaged vertebral body was then treated by vertebroplasty. Before and after fracture, and again after vertebroplasty, each specimen was subjected to a static compressive force of 1kN for 1h while elastic and creep deformations were measured in the anterior, middle and posterior regions of each adjacent vertebral body cortex, using a 2D MacReflex optical tracking system. After fracture, creep in the anterior and central regions of the vertebral body cortex increased from an average 4513 and 885 microstrains, respectively, to 54,107 and 34,378 microstrains (both increases: P<0.001). Elastic strains increased by a comparable amount. Vertebroplasty reduced creep in the anterior and central cortex by 61% (P=0.006) and 66% (P=0.017) respectively. Elastic strains were reduced by less than half this amount. Results suggest that the beneficial effects of vertebroplasty on the vertebral body continue long after the post-operative radiographs. Injected cement not only helps to restore vertebral shape and elastic properties, but also reduces subsequent creep deformation of the damaged vertebra.

Magnetic resonance imaging in the investigation of sensorineural hearing loss: is contrast enhancement still necessary?

High resolution T2-weighted magnetic resonance (MR) imaging has been proposed as a rapid, inexpensive means of investigating patients with sensorineural deafness, particularly to exclude vestibular schwannomas. Whether the accepted 'gold standard' of contrast-enhanced T1-weighted images can be omitted, however, remains controversial. Over a 22-month period the use of axial turbo-spin echo T2-weighted images (T2W) were prospectively compared with contrast-enhanced T1-weighted spin echo scans in the evaluation of 513 patients presenting with audiovestibular symptoms. A 2-D T2W turbo spin echo (TSE) sequence with 3 mm slices was used in 340 patients while a 3-D sequence with overlapping 1 mm slices was used in 173 patients. The T2-weighted image findings were documented and subsequently compared with contrast-enhanced images. With the 2-D sequence 24 patients (25 lesions) had internal auditory meatus (IAM)/cerebello-pontine angle (CPA) masses identified by contrast-enhanced T1-weighted images, all of which were seen on the T2-weighted TSE sequence; there was one false positive 'mass' on the T2-weighted scans and one false negative case of IAM dural enhancement on T1-weighted imaging; six were considered normal initially on the T2-weighted images although three were subtly abnormal in retrospect. With the 3-D sequence three acoustic neuromas were all identified correctly with no false positive and only one false negative result (labyrinthitis). The 2-D and 3-D images were judged technically inadequate for clinical assessment in 15 and nine per cent respectively. We conclude that mass lesions of the IAM/CPA can be reliably identified on T2W TSE imaging but labyrinthine lesions may be missed without contrast enhancement. This is of particular importance in planning the management of neurofibromatosis type 2. Non-neoplastic disorders of the inner ear are also likely to be missed.

Endovascular approach to treatment of indirect carotico-cavernous fistulae.

The purpose of the study was to assess the cure rate in patients with indirect carotico-cavernous fistula (CCF) treated by transvenous embolisation via the inferior petrosal sinus (IPS) pathway or the superior ophthalmic vein (SOV). Twelve fistulae in 11 patients were treated by transvenous embolisation, eight patients via the IPS and four fistulae in three patients via the SOV. Angiographic cure was defined as complete obliteration of the fistula and clinical cure as total resolution of signs and symptoms. Complete cure was achieved in eight patients with nine fistulae embolised transvenously. Five fistulae were approached via the IPS and four via the SOV. Our preferred method for treatment of indirect CCF is the transvenous route. The IPS approach is technically easier and has fewer potential risks than the SOV approach. However, if the IPS is not patent the SOV can provide good alternative access to the cavernous sinus.