Intracranial circulation: pulse-sequence considerations in three- dimensional (volume) MR angiography

The technique and feasibility of magnetic resonance (MR) angiography of intracranial vessels were studied in 35 healthy volunteers. Variations in image orientation, repetition time (TR), and flip angle were evaluated to determine their effects on flow-related enhancement. Gradient modifications--including echo time (TE), motion compensation, bandwidth, and field of view--were also studied in an effort to reduce motion-induced phase shifts. Results indicated that a FISP (fast imaging with steady precession) sequence with a TR of 50 msec, TE of 15 msec, velocity compensation in the read and section-select directions, acceleration compensation in the read direction, anisotropic volume, and a 1.25-mm partition thickness produced three-dimensional angiographic MR images that were accurate and reproducible in the depiction of the major intracranial vessels. Difficulties with field of view, persistent signal void secondary to higher-order motion, and spatial resolution remain major problems requiring additional study.     

Paediatric dacryocystorhinostomy

Of 258 cases of dacryocystorhinostomy performed on children in the period September 1981 to September 1991, 130 were for simple, unresolved congenital nasolacrimal duct obstruction. Other indications for surgery included punctal agenesis, lacrimal fistula, post-traumatic and post-inflammatory canalicular obstruction. Of 177 children without canalicular pathology, 171 (96%) were relieved of symptoms with one operation, without canalicular intubation. Of 81 cases with canalicular disease, 55 of 70 (79%) who underwent DCR plus canalicular intubation, and 10 of 11 who underwent DCR plus Lester-Jones tube, were substantially improved with one operation. No child required peroperative or postoperative blood transfusion. Dacryocystorhinostomy in childhood, in experienced surgical hands, is a safe procedure, achieving relief of symptoms in most cases, particularly in the absence of canalicular disease.     

Subpially recorded cervical spinal cord evoked potentials in syringomyelia.

Intraoperative spinal cord evoked potentials (SCEPs) to median nerve stimulation were detected subpially from the dorsal surface of the cervical spinal cord in 5 patients with cervical syringomyelia and were compared to normal SCEPs obtained from the unaffected side in 6 patients during intraoperative monitoring of dorsal root entry zone lesion. Normal SCEP began with a positive deflection P9 and a complex N11/N13 with several low amplitude short potentials superimposed on the N11/N13. The complex was followed by a second negative potential N2 and a late prolonged positivity, P. In the 4 patients in whom median nerve somatosensory evoked potentials (SEPs) were present preoperatively, SCEP consisted of the N11 potential and the following low amplitude short (LAS) potentials, while the N13 wave was missing. In the fifth patient, in whom the preoperative median nerve SEP was missing, SCEPs were of much lower amplitude and shorter duration than normal. The potentials N2 and P were not recorded in any of our 5 patients. Changes in N13 wave, N2 and P potentials noted in syringomyelia were presumed to be the result of destruction of the spinal cord dorsal horn neurons caused by spinal cord central cavitation.     

Predominance of null mutations in ataxia-telangiectasia

Ataxia-telangiectasia (A-T) is an autosomal recessive disorder involving cerebellar degeneration, immunodeficiency, chromosomal instability, radiosensitivity and cancer predisposition. The responsible gene, ATM, was recently identified by positional cloning and found to encode a putative 350 kDa protein with a Pl 3-kinase-like domain, presumably involved in mediating cell cycle arrest in response to radiation-induced DNA damage. The nature and location of A-T mutations should provide insight into the function of the ATM protein and the molecular basis of this pleiotropic disease. Of 44 A-T mutations identified by us to date, 39 (89%) are expected to inactivate the ATM protein by truncating it, by abolishing correct initiation or termination of translation, or by deleting large segments. Additional mutations are four smaller in-frame deletions and insertions, and one substitution of a highly conserved amino acid at the Pl 3-kinase domain. The emerging profile of mutations causing A-T is thus dominated by those expected to completely inactivate the ATM protein. ATM mutations with milder effects may result in phenotypes related, but not identical, to A-T.      

En bloc resection of an intracavernous oculomotor nerve schwannoma and grafting of the oculomotor nerve with sural nerve. Case report and review of the literature

A case in which a left oculomotor nerve schwannoma treated by en bloc resection of the lesion and grafting of the oculomotor nerve with sural nerve is presented. Recovery of nerve function was partial, but useful and cosmetically good. The last follow-up examination performed 2 years after surgery revealed recovery of function in the elevator muscle of the upper eyelid, together with slight vertical movement of the eye.