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Biomedical subjects

G Maira

Publications and source records attributed to G Maira.

At least 19 recordsLinked to original sources
PubMed1992

A motion correction algorithm for an image realignment programme useful for sequential radionuclide renography.

The correction of organ movements in sequential radionuclide renography was done using an iterative algorithm that, by means of a set of rectangular regions of interest (ROIs), did not require any anatomical marker or manual elaboration of frames. The realignment programme here proposed is quite independent of the spatial and temporal distribution of activity and analyses the rotational movement in a simplified but reliable way. The position of the object inside a frame is evaluated by choosing the best ROI in a set of ROIs shifted 1 pixel around the central one. Statistical tests have to be ful-filled by the algorithm in order to activate the realignment procedure. Validation of the algorithm was done for different acquisition set-ups and organ movements. Results, summarized in Table 1, show that in about 90% of the simulated experiments the algorithm is able to correct the movements of the object with a maximum error less or equal to 1 pixel limit. The usefulness of the realignment programme was demonstrated with sequential radionuclide renography as a typical clinical application. The algorithm-corrected curves of a 1-year-old patient were completely different from those obtained without a motion correction procedure. The algorithm may be applicable also to other types of scintigraphic examinations, besides functional imaging in which the realignment of frames of the dynamic sequence was an intrinsic demand.

Algorithms↗
PubMed1992

[Evaluation of the thyroid function in healthy aged patients residing in 2 geriatric institutions].

Thyroid function assessment in elderly inpatients. It is not well known whether normal ageing might lead to an impairment of thyroid function. We evaluated 297 elderly inmates in two geriatric institutions. After having excluded from the study those who were affected by chronic hepatic or renal disease, were under pharmacologic treatment or had suffered from acute ailments during the previous two months, we assessed thyroid function by determining circulating T4, T3, rT3, FT4, FT3 and TSH in 130 apparently healthy subjects. They could be divided into three groups composed of patients mentally competent, affected by either vascular or senile dementia, or affected by chronic psychosis. Results were also assessed with reference to three different age ranges (65-74, 75-84 and over 85 years). Two patients had subnormal thyroid hormone levels with elevated basal thyrotropin, while other two demonstrated only elevated thyrotropin levels, qualifying respectively for a diagnosis of primary hypothyroidism and subclinical hypothyroidism. In the remaining 126 patients thyroid function was normal, and no differences in thyroid hormone levels could be noticed among the various groups of patients, divided for sex, age range and mental condition. The results of our study confirm the presence of a high percentage of subclinical thyroid dysfunction in old age. They also suggest that in healthy aged subjects thyroid function parameters are not significantly different in reference to sex, age range and mental condition.

Age Factors↗
PubMed1991

Cerebrospinal fluid shunting for hydrocephalus in the adult: factors related to shunt revision.

Cerebrospinal fluid shunting procedures are widely employed in the treatment of hydrocephalus and other disturbances of the dynamics of cerebrospinal fluid. In spite of its popularity, this operation frequently requires surgical revision. A retrospective analysis of a series of 356 adults who underwent the insertion of a cerebrospinal fluid shunt between January 1970 and December 1988 was performed. The incidence of revision was analyzed, and an attempt was made to identify possible causal factors. The overall incidence of surgical revisions was 28.65%; the number of revisions in the same patient ranged between one and eight. The most frequent causes of revision were distal malposition, obstruction, and infection. A statistically significant difference (P less than 0.05) was found in both the risk of revision in patients who had undergone previous operations and those who had not and in the incidence of revision before and after January 1985. Meticulous surgical technique as well as perioperative antibiotic prophylaxis appear responsible for the latter. The differences in the incidence of revision among patients treated with different types of shunts and valves, though remarkable, is not statistically significant.

Adolescent↗
PubMed1991

Post-endarterectomy headache and the role of the oculosympathetic system.

A study was carried out on headache after carotid endarterectomy. A specific type of headache, similar in its characteristics to "cluster headache", occurred on the operative side in 30% of 54 patients, whereas no such headache occurred after extra-intracranial bypass or peripheral vascular surgery. This postoperative headache was not spontaneously reported by 56% of patients unless they were specifically asked about it. Pharmacological pupillary testing performed in 37 patients revealed that a decreased oculosympathetic activity (with or without adrenoceptor supersensitivity) was constantly associated with post-endarterectomy headache. Although this same abnormality was also observed in 54% of the patients without headache, a statistically significant (p less than 0.01) higher prevalence of decreased oculosympathetic responses was found in the patients with headache. The results suggest that damage to the sympathetic plexus due to the surgical procedure is involved in the development of postoperative "cluster-like" headache.

Carotid Artery Thrombosis↗
PubMed1990

Therapeutic possibilities of 131I-MIBG in metastatic carcinoid tumors--preliminary report.

The poor results of traditional therapy in advanced carcinoid tumors and the well-proven uptake of 131I-MIBG shown by some of these tumors induced us to attempt a radiometabolic approach. We selected for the treatment 5 patients (3 men and 2 women) who showed progression of disease, a fairly good uptake of 131I-MIBG with severe related symptoms, and a poor response to traditional therapy. A cumulative radioactivity of 5.5-29.6 GBq was given. Acute side effects after 131I-MIBG administration or late radiation-induced damages were not observed. Symptoms increased during the first 2-4 weeks in 2 patients: in one of these relief was achieved with drugs. Results concerning objective remission of the disease were unsatisfactory. In contrast, definite improvement of symptoms was shown in 2 of 5 patients, resulting in a better quality of life.

3-Iodobenzylguanidine↗
PubMed1990

Hemodynamic effects of decompressive craniectomy in cold induced brain oedema.

An experimental model of cold induced brain oedema was carried out in 7 albino rabbits by topic application of fluid N2 on the skull to examine the favourable effects of an appropriate tailored craniodural opening both on the whole brain perfusion and on the local dynamics of the oedematous fluid. After positioning the animals in a stereotactic frame the following parameters were recorded: ICP, carotid blood pressure and flow velocity, EEG, EKG. Histological staining with Evan's blue was utilized to check fluid extravasation. In all the animals the lesion was followed both by an ICP increase and a reduction in the carotid blood flow velocity so indicating an increase in the cerebrovascular resistances. In 4 animals the removal of the craniodural flap over the lesion dramatically reduced the ICP values and normalized the blood flow velocity. No difference in the Evan's blue distribution was noticed between the two groups of animals.

Animals↗
PubMed1990

Prolactin-secreting adenomas--surgical results.

The long-term follow-up of the transsphenoidal microsurgical treatment in 119 consecutively operated women with a PRL-secreting adenoma is presented. An apparent total removal of the tumor was achieved in 98 cases with an enclosed tumor (58 grade 1 and 40 grade II). In the remaining cases the removal was considered partial. The achievement of persistent normal PRL basal levels was verified in 61 patients (44 grade I and 17 grade II) who had an apparent total removal of the adenoma. In the 37 remaining patients who were thought at surgery to have had total removal we have distinguished two groups: 30 patients showed a "relapse" or "persistence" of PRL levels below 200 ng/ml without clinical and radiological signs of tumor regrowth, and 7 patients with a PRL level higher than 200 ng/ml who had evidence of PRL-secreting tumor recurrence.

Adolescent↗
PubMed1990

Pituitary adenomas in childhood and adolescence.

Pituitary adenomas are considered rare tumors in the pediatric age group. The natural history in this age group is not well known, although many authors have suggested that pituitary adenomas in children tend to be extrasellar and invasive and that a subfrontal approach is mandatory in the majority. Our patients were part of a surgical series of 356 adenomas of all ages. We have divided these cases into three groups: the first consists of patients operated on before the age of 21 years (52 cases, 15%); the second, patients treated after the age of 20 but in whom the clinical history started before 21 years (52 cases, 15%); the third, patients with surgery and symptoms after 20 years (252 cases, 70%). Transsphenoidal removal of the adenomas was the initial procedure in all but one of these cases; a few required a second intracranial operation. In our series, pituitary adenomas in children were not more invasive than in other age groups.

Adenoma↗
PubMed1990

Cerebrospinal fluid pressure and prolactin in empty sella syndrome.

In 58 female patients with the primary empty sella (PES) syndrome, a study of the CSF dynamics was done by evaluating both the absorptive reserve by a lumbar infusion test at constant rate, and/or the ICP increase occurring during REM phase of nocturnal physiological sleep. In 33, prolactin (PRL) dynamics were also investigated evaluating both the response to sequential stimulating test with thyrotropin-releasing hormone (TRH) and metoclopramide (MCP) and/or the circadian variation of PRL levels. Impairment of CSF dynamics was found in the 84% who had a hormonal pattern characterized by an increase of the PRL response to TRH and MCP and a decrease of the PRL circadian variation. Twenty-one patients with impaired CSF dynamics underwent CSF shunting procedures with disappearance of the signs of intracranial hypertension. They also had restoration of normal PRL dynamics but the endocrine alterations improved only moderately. Altered CSF dynamics play a role in the pathogenesis of the PES syndrome. A correlation between elevated ICP and the hypothalamo-hypophyseal control of PRL secretion may exist.

Adult↗
PubMed1990

Paradoxical growth hormone response to thyrotropin-releasing hormone in acromegaly. Clinical correlations and prognostic value.

We have investigated the effect of TRH on the release of GH in 20 acromegalic patients (14 females and 6 males) before and after selective removal of a pituitary tumour via transsphenoidal route. The follow-up period was 8 years. Pre-operatively the paradoxical response was present in 15 patients (75%). Mean GH values in TRH responders were significantly lower than in non-responders. According to the size and expansion diffusion of the adenoma, the patients were divided into 3 classes. The percentage of paradoxical response in patients in class III was significantly lower than in the other two classes. Postoperatively, mean GH values in pre-operative TRH responders were significantly lower than in non-responders; among 15 responders, 13 (86%) had postoperative GH levels under 5 micrograms/l; among 5 non-responders only 2 (40%) had GH values under 5 micrograms/l. Postoperatively 8 patients still had GH responsiveness to TRH: 6 with GH levels persistently (follow-up 8 years) under 5 micrograms/l and 2 with elevated GH values. The other 7 patients, who were responders pre-operatively and non-responders postoperatively, persistently exhibited low GH levels, except one subject who showed an increase in GH levels with reappearance of the paradoxical response, two years after surgery. These results suggest: 1. the paradoxical response may be expressed only when the hypothalamus-pituitary interactions are intact; 2. the disappearance of the paradoxical response cannot surely suggest a remission, and 3. the presence of a pre-operative paradoxical response is a good prognostic feature.

Acromegaly↗
PubMed1989

New tracers for the imaging of the medullary thyroid carcinoma.

I-MIBG and 99Tcm(V)-DMSA have been recently proposed as scintigraphic markers of the medullary thyroid carcinoma (MTC). Thirty two patients were examined with 131I- or 123I-MIBG and 26 of these were re-examined with 99Tcm(V)-DMSA (planar and SPECT). From our experience we can draw the following conclusions: (1) the scintigraphic attempt was useless in patients with normal levels of plasma calcitonin (CT): (2) in patients with high plasma CT levels, the sensitivity of the MIBG was better in familiar (3/3 true positive) than in sporadic disease (7/21 true positive; overall sensitivity = 42%); the 99Tcm(V)-DMSA was positive in 16/19 cases, (overall sensitivity = 84%) even in cases which had been false negative with MIBG (6 patients); (3) no false positive results were found; (4) the scan with 99Tcm(V)-DMSA is then suggested as the first imaging approach during the follow up in patients affected by MTC and still having high levels of plasma CT. The MIBG scan should be limited to the patients in whom the possible use of MIBG therapy has to be investigated.

3-Iodobenzylguanidine↗
PubMed1989

Prolactin-secreting adenomas: surgical results and long-term follow-up.

Transsphenoidal surgery is an efficacious treatment for patients with prolactin (PRL)-secreting adenomas, even if disrupted pituitary-hypothalamic relationships may persist and/or a recurrence of the PRL-secreting tumor can occur. In this paper, we analyze the long-term follow-up of 119 consecutively treated women who underwent transsphenoidal microsurgery for PRL-secreting adenomas. Apparent total removal of the tumor was achieved in 98 patients who had enclosed tumors (58 with Grade-I tumors and 40 with Grade II). In the remaining patients, the removal was considered partial. Persistent normal basal PRL levels were achieved in 61 patients who had apparent total removal of the adenoma (44 with Grade I tumors and 17 with Grade II). Of the remaining 37 patients in whom surgical removal of the adenomatous tissue was thought to be total, 30 had persistent nonevolutive, high PRL levels ranging from 21 to 196 ng/ml, without clinical and radiological signs of tumor regrowth, and 7 with PRL levels ranging from 56 to 560 ng/ml had a recurrence of the PRL-secreting tumor. These data seem to indicate that a slightly elevated postsurgical PRL value does not imply that tumoral tissue is still present. Nontumoral conditions (i.e., a secondary empty sella) could induce functional hyperprolactinemia.

Adenoma↗
PubMed1987

Intracranial pressure behaviour and its relation to the outcome of surgical CSF shunting in normotensive hydrocephalus.

Twenty-four patients with suspected normotensive hydrocephalus were surgically treated by cerebrospinal fluid (CSF) ventriculoatrial or peritoneal shunt. The results of surgery were considered in relation to clinical history and different diagnostic examinations: pneumoencephalography, CT scan, isotope cisternography, transfer from CSF to blood of isotope-labelled serum albumin, constant infusion manometric test, intraventricular pressure recording. Intracranial pressure (ICP) was analysed during both resting conditions and spontaneously (REM phase of sleep) or artificially induced (jugular compression) increases. The ventricular enlargement (as shown by CT scan) and the slope of the intracranial elastance (the ratio of the differences between the maximum and minimum values of pulse ICP and the correspondent values of the diastolic ICP under the same dynamic conditions) provided the most reliable data for diagnosis and surgical prognosis.

Cerebrospinal Fluid Shunts↗
PubMed1986

Total excision of spinal lipomas using CO2 laser at low power. Experimental and clinical observations.

Total excision of spinal lipomas (SL) is difficult because of the intimate adhesion between the fibro-adipose tissue and the neural structures. Radical surgery in SL can provoke nervous lesions; therefore many authors recommend only partial excision as a means of decompression. Nevertheless the role of traction or tethering of the spinal cord in all spinal disraphism, including SL, is known to be very important in determining the clinical picture. So partial removal of SL cannot be effective in releasing the tethered cord. The use of a CO2 laser at low power (3-5 W) permitted radical surgery without any neural damage and complications in 2 adult patients with large, not well capsulated SL. These patients were previously operated on by the same surgeon with conventional microsurgical techniques for partial excision. After CO2 laser surgery there was significant improvement of the clinical pictures, the follow-up being respectively 24 and 36 months. This clinical experience was performed after a CO2 laser had successfully been used in an experimental model in rats simulating a condition of SL. Using power of 3-5 W was not sufficient to attain an immediate vaporization, but the adipose tissue first changed into a transparent liquid across which it was possible to recognize the interfaces between the neural structures and the adipose tissue.

Adult↗
PubMed1979

Prolactin-secreting pituitary adenomas: prolactin dynamics before and after transsphenoidal surgery.

Twenty women with hyperprolactinaemia secondary to a pituitary adenoma were studied before and after selective transsphenoidal removal of the tumour. Pre-operatively, thyrotrophin-releasing hormone (TRH) (200 micrograms iv) and metoclopramide (MCP) (10 mg po) did not produce a positive PRL response in the tumour patients. By contrast, 14 post-partum lactating women, who were used as controls, exhibited a positive response to MCP administration. Methergoline (4 mg po) was shown to decrease serum PRL levels in 8 normal subjects, in 6 puerperal women, and 9 of 10 tumour patients. Bromoergocriptine (CB-154, 2.5 mg po) decreased serum PRL levels in 10 tumour patients. Following transsphenoidal removal of the adenoma serum PRL levels were reduced in all patients, and returned to normal in 14 patients. Prognostics for completely normalizing PRL secretion after transsphenoidal surgery is bettery when initial serum PRL levels are below 200 ng/ml. After surgery all hyperprolactinaemic patients failed to show a positive PRL response to TRH and MCP. Nine normoprolactinaemic patients had a positive response to both stimuli while 3 patients failed to show a positive response immediately following surgery. Long-term studies, however, showed that a positive PRL response was obtained in all patients tested 8-14 months after treatment. A positive PRL response to methergoline and bromocriptine was observed post-operatively in the patients tested regardless of their basal PRL level. Data from this study indicate that surgically proven PRL-secreting adenomas are invariably associated with negative PRL responses to TRH and MCP. The normalization of the prolactin regulation after surgery points toward the intrapituitary localization of the lesion associated with PRL-secreting adenomas.

Adenoma↗
PubMed1978

The value of CT for the diagnosis of pituitary microadenomas in children.

Three cases of prepuberal hypopituitary dwarfism regarded as idiopathic, are reported. In two of them the skull X-rays showed questionable minimal alterations of the sella turcica; in the remaining child the examination was completely negative. All three children were found to have a pituitary intrasellar microadenoma on the CT scan. The diagnosis was confirmed during surgery. The postoperative followup demonstrated the relation of the lesion with growth retardation and the indication for surgical treatment.

Adenoma, Chromophobe↗
PubMed1978

Serum prolactin response to thyrotropin-releasing hormone and metoclopramide in patients with prolactin-secreting tumors before and after transsphenoidal surgery.

Seven female patients with amenorrhea, galactorrhea, and hyperprolactinemia were examined before and after selective transsphenoidal removal of a PRL-secreting microadenoma. Before adenomectomy, metoclopramide (MCP; 10 mg orally) and TRH (200 micrograms iv) did not increase PRL blood levels in any of the seven patients. On the contrary, after oral administration of 10 mg MCP, a positive response was noted in a group of eight lactating women 3 days postpartum. After surgery, serum PRL level returned to normal in all patients. A positive PRL response to MCP and TRH was found in six of the seven patients 1 month after surgery. One patient, who had the lowest PRL level, failed to show a PRL increase after both stimuli. These findings indicate that hypothalamic pituitary function can be restored to normal after transsphenoidal removal of PRL-secreting pituitary tumors.

Adenoma↗