Biomedical subjects

A Landi

Publications and source records attributed to A Landi.

At least 55 records · Page 3Linked to original sources

PubMed1991

Pressure monitoring inside Meckel's cave during percutaneous microcompression of gasserian ganglion.

During percutaneous microcompression of the gasserian ganglion for the relief of trigeminal neuralgia, a computerized technique for monitoring the pressure inside Meckel's cave was employed in 22 patients. A dedicated transducer connected to a computer records the balloon inflation pressure. Its variations are discernible within tenths of a bar and are plotted in relation to time. The intraoperative pressure inside Meckel's cave is from 0.9 to 2.4 bars. When pressure was low, there was recurrence of pain. The highest values of pressure (1.9-2.4 bars) were observed in most of the patients suffering from untoward side effects. The clinical results seem to be influenced by the level of the intraoperative intracavitary pressure.

Aged↗

PubMed1991

Brain stem acoustic evoked potentials recorded from the human mesencephalon.

Near field brain stem evoked potentials (NF-BAEPs) were recorded by means of an intraparenchymatous electrode placed in the right mesencephalon, during a stereotactic-guided biopsy of a tumor. The traces were compared with far field BAEPs (FF-BAEPs) obtained intraoperatively with scalp electrodes. The findings suggest a peripheral origin of wave II, a bilateral source of wave III and a main contralateral source of wave IV, while wave V seems to take origin mainly from the homolateral upper brain stem. Some intraparenchymatous activities do not project to the scalp. The possible impairments of NF-BAEP due to the presence of the tumor and the challenges of unidimensional single electrode recording are discussed.

Acoustic Stimulation↗

PubMed1991

Serum elastase-type enzymes and their correlation to blood lipids in male patients with atherosclerosis.

Serum elastase-type activity, elastase inhibitory capacity and their relation to lipids were examined in 140 male patients with ischaemic vascular disease (coronary, cerebral, peripheral) and in 60 control subjects. Serum elastase-type activity was found to be significantly lower, inhibitory capacity significantly higher, in the groups of patients than in the controls. HDL- and HDL2 cholesterol as well as apo A concentration showed significant negative correlation with elastase inhibitory capacity both in atherosclerotic and in control subjects.

Apolipoproteins A↗

PubMed1990

Carpal tunnel syndrome: correlations between pressure measurement and intraoperative electrophysiological nerve study.

In 19 carpal tunnel syndrome (CTS) patients and 4 control subjects a catheter was introduced into the carpal tunnel and slowly retracted in 5 mm steps. Pressure was measured with the continuous infusion technique. In the same group of patients and controls, median nerve antidromic sensory action potential (aSAP) was detected intraoperatively stimulating proximally (S1), in the center (S2), and distally (S3) to the carpal tunnel and recording from the third finger (R). Sensory conduction velocity (SCV) and aSAP amplitude were considered in S1-S2, S2-S3 and S3-R segments. The intracarpal tunnel pressure was significantly higher in CTS patients than in controls, with the highest values located between 25 and 35 mm distal to the proximal border of the flexor retinaculum. SCV and aSAP amplitude were also decreased most often in the distal part (S2-S3) of the carpal tunnel.

Carpal Tunnel Syndrome↗

PubMed1990

Morphology and neurophysiology of focal axonal injury experimentally induced in the guinea pig optic nerve.

A new model of focal axonal injury was reproduced by rapid and controlled elongation (uniaxial stretch) of the guinea pig optic nerve. Light microscopy study of optic nerve specimens after horseradish peroxidase injection into the vitreous of the animal's eye showed that axonal lesions were identical to those seen in human and primate post-traumatic diffuse axonal injury (DAI). The lesions were characterized by the formation of terminal clubs in severed axons and focal axonal enlargements in those axons that were lesioned-in-continuity. Visual-evoked potentials upon flash stimulation were recorded before and after injury. Mean amplitude and mean latency of occipital peaks were significantly elongated in the acute post-traumatic phase. Electron microscopy examination showed that the main axonal changes observed in this model were cytoskeleton disorganization, accumulation of axoplasm membrane-bound bodies at the site of terminal balls and dilatations-in-continuity and detachment of the axolemma from the myelin sheath. Such axonal alterations were similar to those found in many other biological models of central and peripheral axonal injuries in which the lesion was produced by invasive methods. This model is unique since it reproduces the same mechanism of injury and the identical lesions that have been demonstrated in humans and primates with post-traumatic (DAI).

Animals↗

PubMed1990

Multimodality evoked potentials in HIV infected subjects: a longitudinal study.

18 subjects with symptomless HIV infection were investigated with multimodal evoked potentials for possible CNS involvement and again after an 8-12 month interval. 13 subjects showed neuropsychological changes, which were confirmed at the second examination. The 5 subjects found normal remained so at the second examination. On WAIS assessment the only patient to earn pathological scores was the one with the greatest evoked potentials changes. Thus the evoked potentials procedure proved capable of identifying early CNS involvement by HIV infection.

Adult↗

PubMed1990

Intra-operative monitoring by means of somatosensory evoked potentials during cerebral aneurysms surgery.

During cerebral aneurysms surgery, brain tissue may suffer for global or local ischemia due to deliberate hypotension and surgical manoeuvres. Somatosensory evoked potentials (SEPs) can detect functional derangements consequent to hypoxia, before a permanent brain damage is produced. Forty two patients, undergoing cerebral aneurysms surgery for treatment of SAH, were evaluated intraoperatively with SEP recordings. It has been stressed that no permanent neurological damage is to be expected if the absolute value of Central Conduction Time (CCT) does not exceed 9.5 ms for 10 min at least and the cortical waves are visible throughout the whole procedure. SEP changes are strictly related with MAP decrease and surgical handlings.

Adult↗

PubMed1990

The transcranial Doppler ultrasonography in the evaluation of vasospasm and of intracranial hypertension after subarachnoid hemorrhage.

The transcranial doppler (T.C.D.) is a non-invasive technique useful for the evaluation of vasospasm and intracranial hypertension in patients with subarachnoid hemorrhage (S.A.H.). Eighteen patients with recent S.A.H. were studied by means of T.C.D. device: in 14 patients the source of bleeding was a ruptured aneurysm of the circle of Willis, while the remaining 4 presented a negative four-vessels angiography. All the patients were studied 5 and 10 days after the bleeding. Our data showed that the ultrasonographic demonstration of vasospasm and/or I.C.H. is clearly related to the clinical status of the patients. No significant T.C.D. difference was noticed between the "sine materia" S.A.H. patients and the ones with ruptured aneurysm.

Blood Flow Velocity↗

PubMed1989

CT in established Volkmann's contracture in forearm muscles.

Differential diagnosis between true and pseudo-Volkmann's contracture should not be based on clinical grounds alone, because clinical data are often insufficient in determining the severity and the extent of muscle damage. CT has been utilised in 11 cases where a flexion contracture of the forearm muscles was present and corresponded closely with the surgical findings. True and pseudo-Volkmann's contracture can thus be distinguished and the severity and extent of the muscle damage determined.

Adolescent↗

PubMed1989

Pseudarthrosis of the radius treated by free vascularised bone graft.

We report a case of pseudarthrosis of the radius successfully treated by free vascularised bone grafting. After a comprehensive review of the literature, we recommend this as the treatment of choice in this condition. We also report the use of callus distraction of an incorporated vascularised bone graft to achieve bone lengthening.

Bone Lengthening↗

PubMed1989

Carpal-tunnel pressure.

Using the constant infusion technique, we have measured the pressures within the carpal tunnel in 30 hands in patients with carpal tunnel syndrome and in 4 hands in control subjects. The mean pressure in the normal, control subjects was 13 mmHg and in the carpal tunnel syndrome patients 26 mmHg. In the normal subjects the pressures did not change along the canal, whereas in the patients the values in the middle section were 50 percent higher than the mean. Our results correspond to reports of computed tomography and magnetic resonance recordings of nonuniform dimension of the carpal tunnel.

Adult↗

PubMed1989

The use of CT scan in evaluating Volkmann's syndrome in the limbs.

Between January 1980 and October 1986 26 cases of Volkmann's syndrome were submitted to preoperative CT scan. Thirteen were localised in the upper limb, 11 in the lower limb, and 2 were cases of pseudo-Volkmann's disease. CT scan allowed us to confirm the densitometric features and distribution of muscle infarction in the various muscle planes. Thus, two groups were distinguished, each with different densitometric features: a first group with diffuse hypodensity of the muscular sheaths with unclear borders, and a coefficient of attenuation at approximately 30-40 H.U., which at operation corresponded to diffuse fibrosis; a second group with defined hypodensity of the various muscle groups equal to 10-20 H.U., which at operation gave a macroscopic picture of infarction. CT scan provides a detailed preoperative topographical and morphological evaluation of the infarction area, and therefore a treatment plan based on a more accurate knowledge of the anatomical and pathological lesions.

Adolescent↗

PubMed1988

Monitoring of brain function by means of evoked potentials in cerebral aneurysm surgery.

Deliberate arterial hypotension is currently used to operate upon cerebral aneurysms. However, it is not ascertained whether this practice is really safe for all patients, especially those presenting with preoperative vasospasm. 50 patients, requiring surgical treatment for cerebral aneurysm, have been submitted, during surgery, to the recording of Somatosensory Evoked Potentials (SEPs) on median nerve stimulation. This technique allows the functional evaluation of neural pathways mediating the somatosensory stimuli and of primary somatosensory cortex; it is known that a decrease of cerebral perfusion may affect the SEP waveforms in terms of reduced subcortical conduction velocity (i.e., increased central conduction time, CCT) and of reduced cortical response amplitude. These changes may be apparent before a permanent neurological damage is produced. Preoperative SEP recording demonstrated a prolonged CCT, possibly related to vasospasm, in 9 patients, a normal clinical evaluation notwithstanding (grade I and II). During intraoperative deliberate hypotension, a SEP change has always been produced. No postoperative damage has been observed, however, as long as the CCT did not exceed 9 msec for 10 minutes (maximum normal CCT value is 6.7 msec) and as the cortical response had been visible throughout the whole surgical procedure. The critical value of CCT has been reached at a mean arterial pressure (MAP) lower than 60 Torr in patients with a normal preoperative SEP recording; at the opposite, in patients presenting with a prolonged preoperative CCT, the value of 9 msec was arrived at with a MAP value that is generally accepted as safe for all patients (75 Torr).(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia↗

PubMed1988

Pattern reversal visual evoked potentials in phenylketonuria.

The pathogenesis of brain dysfunction in phenylketonuria (PKU) is still under investigation. Hyperphenylalaninaemia results in increased turnover of myelin. In order to demonstrate the derangement of myelinization in PKU we studied the visual evoked potentials (VEP) in 14 PKU patients and in 20 normal subjects. VEP findings were correlated with the metabolic control of the disease and with the electroencephalographic findings. VEP were more sensitive than the EEG in detecting a neurological dysfunction. VEP are influenced by dietary control and are normal only in children with good metabolic control.

Adolescent↗

PubMed1988

Assessment of sensory nerve conduction in carpal tunnel syndrome before, during and after operation.

Sensory conduction velocities of the median nerve before, during and after operation were compared in nine patients with carpal tunnel syndrome and four controls, in order to evaluate the prognostic value of the pre-operative and intra-operative findings. Sensory conduction velocity was higher after operation than before in all patients (mean difference 31.33%), but not in control subjects. One patient showed a dramatic increase of 157% immediately after decompression. Comparing the intra-operative with the post-operative findings all patients but one showed an increase of antidromic sensory conduction velocity (mean 44.37%), while in control subjects again minimal changes were found (mean -4.25%). The study confirms the high diagnostic value of the pre-operative antidromic sensory conduction velocity findings. However, the prognostic value of both pre-operative and intra-operative ASCV findings is low.

Adult↗

PubMed1988

[Blocked metacarpophalangeal joint: etiologic factors and treatment].

The metacarpo-phalangeal is a crucial joint and its stiffness deeply affects hand function. A series of 15 post-traumatic cases resulting in a complete and irreversible block of the joint is presented. Indication for joint release are given and the surgical technique is described. Different approaches are utilized in relationship to associated lesions. Post-operative treatment and percentages of improvement in joint excursion for each digit are reported. All working patients resumed the previous job even in presence of a limited articular gain. Best results where confined uncomplicated post-traumatic cases with crushing of surrounding soft tissues.

Adolescent↗

PubMed1987

Pattern-reversal visual evoked potentials in phenylketonuric children.

Pattern-reversal visual evoked potentials (PR-VEPs) and EEG were recorded in 14 phenylketonuric (PKU) children on a low-phenylalanine (phe) diet; the data obtained were correlated with metabolic parameters, namely, the actual phe plasma level, the mean phe plasma level in the last year, an the beginning of the diet. PR-VEPs seem to be more sensitive than EEG in detecting neurophysiological derangements in these subjects; in fact PR-VEPs were pathological in six patients while EEG detected three; no significant alterations were found in the neurophysiological tests among the children with good metabolic control, and only one child was abnormal among the six on an early dietetic regimen; in contrast, six of the nine subjects presenting with high mean phe plasma levels (greater than 10 mg/100 ml) and five of the eight whose diet started after the 2nd month of life showed pathological PR-VEPs.

Adolescent↗

PubMed1986

Treatment of secondary hyperparathyroidism of predialysis chronic renal failure with low doses of 1,25(OH)2D3: humoral and histomorphometric results.

Treatment of secondary hyperparathyroidism and the osteodystrophy of predialysis chronic renal failure (CRF) with 1,25(OH)2D3 has been advocated by several authors, but also opposed by others for alleged renal toxicity. However, current concepts of the pathogenesis of the early occurrence of secondary hyperparathyroidism in predialysis CRF point to deficiency of 1,25(OH)2D3 as a primary factor. The aim of this study was to evaluate if administration of 1,25(OH)2D3 (0.25 microgram daily) in a dose which would not induce hypercalcemia, would improve humoral and bone histomorphometric parameters in predialysis CRF. 15 patients with predialysis CRF (mean age 51.2 +/- 16.9 years, range 13-73 years), serum creatinine 4.93 +/- 1.7 mg/dl, were treated with the vitamin D metabolite for an average of 16.2 +/- 11.3 months, at the end of which a transiliac bone biopsy for histomorphometry was performed. In addition, 23 patients comparable for age, serum creatinine and causes of renal failure, served as controls. Treatment did not induce hypercalcemia nor adversely modify the rate of decline of renal function. Alkaline phosphatase fell significantly while immunoreactive parathyroid hormone (iPTH) and osteocalcin showed a moderate, not significant, decrease. Compared to the control patients, the bone histomorphometric parameters active resorption surface and active osteoblastic surface were significantly lower and almost normalized by treatment. In conclusion, the study provides conclusive evidence of the absence of toxicity of the metabolite at the low doses employed, together with good therapeutic response on bone histology. Treatment at this dosage could be made in the early stages of predialysis CRF without need of close and continuous monitoring of serum biochemical parameters.

Adolescent↗