Partial denervation affects both denervated and innervated fibers in the mammalian skeletal muscle.

Partial denervation of the rat extensor digitorum longus muscle was performed by sectioning only one of the sciatic nerve roots. Measurements of spike resistance to tetrodotoxin in individual muscle fibers revealed denervation changes not only in the denervated fibers but also in the adjacent innervated ones. The results support the concept that products of nerve degeneration play a role in the origin of muscle changes induced by denervation.

Spatial summation across the vertical meridian in hemianopics: a test of blindsight.

Twenty hemianopic patients with retrochiasmatic lesions have been tested for spatial summation of pairs of flashes simultaneously presented either to the same hemifield or to opposite hemifields across the vertical meridian. In such a task normal subjects show summation, i.e. a faster reaction time in response to a pair of stimuli than in response to a single stimulus. Such an effect is present both for pairs of stimuli presented within the same hemifield and for pairs of stimuli in which the two flashes are presented one in the right and the other in the left hemifield. In contrast to normals, hemianopics as a group did not show interfield summation although, like normals, showed summation within one hemifield. A single-case analysis, however, revealed that in one patient there was a reliable overall interfield summation and that in three others there was evidence of summation in at least one testing session. The presence of interfield spatial summation between the normal and the affected hemifield of hemianopics thus provides further evidence of blindsight in a task paradigm in which guessing strategies and stimulus artefacts can be eliminated. The very small proportion of patients showing blindsight can be in part related to the relatively low stimulus intensity and the very brief stimulus exposure duration used.

Pulmonary embolism in neurosurgical patients: diagnosis and treatment.

Pulmonary embolism was suspected in 45 neurosurgical patients who were treated between January, 1980, and December, 1981. Hypoxemia with respiratory alkalosis and sudden tachycardia gave rise to this suspicion more often than any other sign or symptom. Perfusion lung scanning confirmed the presence of pulmonary embolism in 23 of these cases. A retrospective analysis of the clinical course of these 23 patients suggested that one or more previous episodes of pulmonary embolism had occurred in 16 cases (69.6%), and had been either overlooked or misdiagnosed. Treatment was started immediately after diagnosis. Twenty-one patients were given heparin; however, two could not be treated because of contraindication to using anticoagulant drugs. Two patients died during treatment. The 21 surviving patients were assessed and 11 of them submitted again to perfusion lung scanning 1 week after diagnosis: 14 had improved, but seven did not show significant changes either clinically or on perfusion lung scanning. Nine treated patients developed hemorrhage, but it was readily controlled. In two of the nine patients, hemorrhage involved the surgical area. It is stressed that pulmonary embolism may be suspected and diagnosed in neurosurgical patients at an early stage. Heparin may be given and the survival rate appears to be better than previously reported figures.

Neurotoxic effects of 2,5-hexanedione in rats: early morphological and functional changes in nerve fibres and neuromuscular junctions.

The study was directed at detecting changes occurring in the early stages of the neurotoxic process induced by an intensive treatment with 2,5-hexanedione. Rats were injected intraperitoneally each day with 450 mg/kg of body weight for the first 14 days and then with 300 mg/kg for an additional 20 days. After 34 days of treatment typical axonal lesions were observed in the sciatic branches, together with electrophysiological signs of denervation in several fibres of the leg muscles. Morphological changes were also found in axons of the spinal cord and optic tracts. At an earlier stage (days 13 to 18), when clinical signs appeared, in the absence of morphological changes in peripheral nerves and of denervated muscle fibres, significant alterations in the functioning of several neuromuscular junctions were observed: increase in frequency and amplitude of miniature end-plate potentials, reduction of the mean quantal content of the evoked end-plate potential (epp) and absence of epp's in some fibres. These changes indicate a progressive functional impairment of nerve terminals which could possibly represent: (a) a primary alteration of the membrane resting and action potentials; (b) a secondary effect of changes in axonal transport. Both these hypothetical events could result from the inhibition of glycolitic enzymes of nervous tissue by 2,5-hexanedione.

Volumetric analysis of CT orbital images.

The determination of the volume of eye muscles is a problem of considerable interest in Graves' ophtalmopathy both with respect to the diagnostic quantisation of the disease and to the measured assessment of the effectiveness of pharmacological treatment. The aim of this research is to design and test an advanced method for processing computerised tomography (CT) orbital images in order to obtain a three-dimensional reconstruction of infra-orbital muscle structures and to analyse them from a morphometric viewpoint. CT images of subjects suffering from Graves' disease were acquired before and after pharmacological treatment with immunosuppressors. They were then processed along with CT images of an anatomical phantom of known volume and fusiform morphology in order to assess the reliability of the procedure and to calculate the effect of the different modalities of acquisition and processing of CT images on the error in volume calculation.

[Primary empty sella syndrome. Clinical and radiological study, and evaluation of pituitary function]. / Sindrome della sella vuota primitiva. Studio clinico, radiologico e valutazione della funzione ipofisaria.

Empty sella syndrome is an anatomoclinical condition in which the herniation of the chiasmatic cavities inside the sella turcica causes deformation of the bone and compression of the hypophysis and its peduncle, often in association with neurological and endocrine symptoms. Over the past four years 22 patients with primary empty sella syndrome were studied at Pisa University's Department of Neurosurgery with particular emphasis on clinical and radiological pictures and hypophyseal function. Pneumocisternography and computerised tomography of the cranium and cavities were used to verify the diagnosis. Radiology showed alterations to the sella turcica in all cases, principally sellar enlargement, doubled sellar floor and erosion of the clinoid processes. Many patients were obese hypertensives with a long history of headaches. Most of the women revealed amenorrhoea, oligomenorrhoea or early menopause. The study of hypothalamus and hypophysis function shows endocrine alterations in almost all cases.

Deformation analysis of brain regions.

The analysis of 2D and 3D deformations applied to structures having non regular geometry is presented. Deformations are studied in order to understand complex dynamic problems coded into image sequences. In particular, methods have been developed suitable to control the reconstruction and the spatial deformation of cerebral structures, in their different aspects of morphometry, isometry and densitometry. Finally, a simulation process of brain deformation caused by a neoplasia in a real relevant clinical case has been performed.

[Effects of partial denervation on the distribution of acetylcholine receptors and other membrane properties in innervated and paralyzed fibers of rat skeletal muscle]. / Effetti della denervazione parziale sulla distribuzione dei recettori per l'acetilcolina ed altre proprieta' di membrana nelle fibre innervate e paralizzate del muscolo scheletrico di ratto.

The origin of the membrane changes induced in skeletal muscle by denervation has been investigated by examining partially denervated rat hindlimb muscles rendered inactive for 2-3 days by a chronic conduction block in the sciatic nerve. Extra-junctional sensitivity to acetylcholine and spike resistance to tetrodotoxin developed to the same extent in the denervated and the adjacent innervated but inactive fibres. On the other hand, impulse-blocked fibres of control muscles not containing denervated fibres showed, at this early time, little membrane changes. These results are interpreted as indicating that the response of muscle to denervation is due to the combined action of inactivity and products of nerve degeneration.

[Degeneration of the afferent fibers simulating the effects of motor denervation on skeletal muscle]. / La degenerazione delle fibre afferenti simula gli effetti della denervazione motoria sul muscolo scheletrico.

Degeneration of afferent nerve fibres was induced in rats in order to observe its effects on the properties of the extra-junctional membrane of soleus muscle fibres. In one approach, removal of dorsal root ganglia L4 and L5 was accomplished in preparations with intact or impulse-blocked (with tetrodotoxin containing cuffs around the sciatic nerve) efferent innervation. Spike resistance to tetrodotoxin developed in the inactive deafferented preparations earlier and to a greater extent than in control, that is only impulse-blocked, preparations. In another series of experiments, efferent denervation alone proved to be less effective than the association of efferent and afferent denervation. On the other hand, section of the afferent fibres central to the dorsal root ganglia was without effect. These results are consistent with the interpretation that products of nerve degeneration contribute together with inactivity to the development of the extrajunctional membrane changes observed in skeletal muscle after denervation.

Partial denervation in inactive muscle effects innervated and denervated fibres equally.

Possible causal factors of denervation-induced changes in muscle include inactivity, products of nerve degeneration and lack of a nerve-borne trophic agent. We now show that if the innervated fibres in a partially denervated rat muscle are rendered inactive, they undergo a reaction as intense as that of the denervated fibres. This provides further support for the view that the effects of denervation on the extrajunctional muscle membrane result from a combination of muscle inactivity and of nerve breakdown products acting diffusely throughout the muscle.

Non-equivalence of impulse blockade and denervation in the production of membrane changes in rat skeletal muscle.

1. A complete and long lasting blockade of nerve impulses was established in the sciatic nerve of rats, by implanting silastic cuffs of critical internal diameters. Either marcaine-impregnated or plain cuffs were used. The contralateral sciatic nerve was sectioned. 2. At various days after the initial procedures, the extensor digitorum longus muscles of the two sides were examined with intracellular electrodes. 3. Decrease in resting membrane potential, fibrillatory activity and resistance of the action potential to tetrodotoxin developed not only in the denervated but also in the impulse-blocked muscles. In the latter, the fibres were normally innervated since they displayed miniature end-plate potentials and were excitable by nerve stimulation distal to the blocking cuff. 4. However, all of the above mentioned denervation-like changes were significantly less pronounced in the blocked muscles than in the denervated ones. 5. It is concluded that in addition to loss of nerve impulses, some other neural factor must be taken into account to explain the origin of muscle changes induced by denervation. The possible relation of this additional factor with nerve degeneration is discussed.

Parkinsonian syndrome in the course of aqueductal stenosis hydrocephalus.

Report of a case of hydrocephalus secondary to stenosis of the aqueduct with associated parkinsonian syndrome. The suggested etiopathogenesis: damage to the striatal system favored by underlying weakness of the basal ganglia.

Effects of chronic nerve conduction block on formation of neuromuscular junctions and junctional AChE in the rat.

The development of ectopic n.m.j.s. between the transplanted superficial fibular nerve and the soleus muscle has been studied in adult rats. Impulse conduction in the sciatic nerve was blocked chronically and synapse formation between the blocked fibular nerve and the paralysed soleus was compared with synapse formation between non-blocked fibular nerves and denervated soleus muscles. Nerves with conduction block readily made new n.m.j.s. Thus 6 and 10--14 days after the onset of the block the number of newly innervated muscle fibres, the percentage of innervated fibres responding with action potentials and the frequency of m.e.p.p.s. at new junctions were comparable to that observed during innervation by non-blocked nerves. Muscle fibres innervated by both the original soleus nerve and the foreign fibular nerve were regularly encountered in the impulse blocked preparations. Junctions formed by impulse blocked fibular nerves had either no or very little AChE activity 10--15 days after the onset of the block. The evidence for this was 1) weak staining for CHE; 2) prolonged rise time and 1/2 decay time of m.e.p.p.s; 3) positive correlation between m.e.p.p. amplitude and 1/2 decay time and 4) insensitivity to anticholinesterases. In contrast, junctions formed by non-blocked fibular nerves had strong AChE activity by these criteria at corresponding times. AChE activity at the original soleus endplates was much reduced 10--15 days after the onset of conduction block.

[Enteral nutrition in the critical neurosurgical patient. Effectiveness and tolerance of a prepared liquid diet]. / Nutrizione enterale nel paziente critico neurochirurgico. Efficacia e tollerabilità di una dieta liquida preconfezionata.

The response of prealbumin was studied in 15 neurosurgical patients following 7 days of enteral nutrition by Nutrisond. Baseline values were compared to day 4 and 7 to assess the degree of change. The prealbumin of day 7 versus baseline value showed a significant increase in the mean serum concentration (16.49 +/- 4.0 vs 19.75 +/- 4.2 mg %). All the patients tolerate well the enteral nutrition with Nutrisond.

[The risk of pulmonary embolism in neurosurgery]. / Il rischio di embolia polmonare in neurochirurgia.

Pulmonary embolism (PE) is a frequent necroscopic finding in neurosurgical patients and this contrasts with the difficult diagnosis of it when the patient is still alive. Such a lack of diagnosis has promoted numerous studies into deep-vein thrombosis (DVT) which is, in most cases, the cause of pulmonary embolism. However, a prophylaxis of DVT cannot be indiscriminately carried out in neurosurgical patients because it is not without potential risks. For this reason we considered it useful to investigate whether among the risk factors for DVT there were any particularly responsible for the development of PE in neurosurgical patients. Our case study was carried out retrospectively on 144 patients hospitalised in the Neurosurgical Institute of Pisa University suspected of PE. In 88 of the cases the suspicion had been confirmed by perfusion lung scanning; in 56, on the other hand, it had been excluded. These two groups of patients resulted homogeneous for sex, age, blood group, and for the presence of any risk factors of cardiovascular diseases. An important difference between the two groups was the pathology which had motivated their hospitalisation; in fact, 50% of the patients with PE were affected by neoplastic pathologies of the CNS, against 28% of the others. The anamenestic evidence of previous neoplastic pathology in different sites of the CNS was much more frequent in patients who had developed PE. As far as the other risk factors we examined are concerned, it resulted that only 12.5% of the patients with PE had presented clinical signs or symptoms of phlebitis.(ABSTRACT TRUNCATED AT 250 WORDS)

Repair of skull defects by autogenous bone grafts.

To repair the infant skull as completely and efficiently as possible, the authors describe and recommend greater use of an autogenous graft taking the outer table of the skull from adjacent or symmetrical sites to the defect.