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Biomedical subjects

J Pyhtinen

Publications and source records attributed to J Pyhtinen.

At least 37 records · Page 2Linked to original sources
PubMed1996

Clinical and computed tomographic findings in costochondral grafts replacing the mandibular condyle.

PURPOSE: The aim of this study was to evaluate by computed tomography (CT) and clinically the structure and function of costochondral grafts (CCG) used to replace the mandibular condyles. MATERIAL AND METHODS: CT and clinical examination were performed in 11 patients with CCGs (9 female, 2 male; mean age at surgery, 25 years; range, 9 to 44 years) approximately 4.5 years after surgery (range, 5 months to 10.5 years). One mandibular condyle was replaced in six patients and two in five patients. RESULTS: Facial asymmetry was observed in two cases and palpation tenderness of the TMJs or clicking and crepitation were found in 10 of 16 operated TMJs. In three cases coronal CT scans showed the graft to be situated laterally in the mandibular fossa, and lateral overgrowth of the graft was seen in three cases. In two cases, coronal CT slices showed that a new fossa had developed. In most cases translatory movement of the graft was minimal. The graft was either partially or almost completely mineralized, especially in cases with longer follow-up. CONCLUSIONS: Most of the patients in this study seemed to have benefitted from replacement of the deformed mandibular condyle with a CCG as estimated by improved range of mandibular movements and decreased symptoms. There were some problems related to unpredictable growth and location of the graft, as well as restricted movement of the replaced condyle. In the future, care should be taken to ensure proper postoperative functional therapy and to examine the role of cartilage thickness on future growth in young patients.

Adolescent↗
PubMed1996

Evaluation of masticatory muscles of edentulous patients by computed tomography and electromyography.

On account of its tissue resolution capacity, computed tomography (CT) is an excellent method for the examination and quantitative analysis of the masticatory muscles. The aim of the present study was to evaluate the influence of the long edentulous period by CT on the structure of the main masticatory muscles in 10 edentulous patients and to study their functioning by electromyography (EMG) in connection with the renewal of the dentures. CT scanning was performed before prosthodontic treatment and EMG recordings of the masseter and temporal muscles before treatment and 4 weeks and 6 months after insertion of the new dentures. The results suggest, however, that a long edentulous period is visible not only in the functioning of the masticatory muscles, in terms of decreased EMG activity, but also as decreased density of the muscles which implies muscle atrophy, as seen by CT in the masseter and medial pterygoid muscles.

Adult↗
PubMed1996

Spontaneous decrease of a pilocytic astrocytoma in neurofibromatosis type 1.

A patient with type 1 neurofibromatosis was followed up with neuroimaging over a period of 12 years. A spontaneous decrease in the size of a histologically verified pilocytic astrocytoma was documented on serial CT and MR examinations. Subsequent studies showed the development of a lesion in the contralateral hemisphere with mass effect and contrast enhancement. Results of a biopsy disclosed normal brain tissue; follow-up imaging showed a spontaneous decrease in the size of this abnormality.

Adult↗
PubMed1995

Superficial siderosis in the central nervous system.

We describe a rare entity, superficial siderosis of the central nervous system, due to multiple small episodes of subarachnoid haemorrhage from any source. Nonspecific neurological findings are associated with deposition of iron-containing pigments in the leptomeninges and superficial layers of the cortex. T2-weighted magnetic resonance imaging demonstrates characteristic low signal in the meninges.

Central Nervous System Diseases↗
PubMed1995

Clinical and MRI findings of the temporomandibular joint in relation to occlusion in young adults.

Magnetic resonance imaging (MRI) is excellent for visualizing soft tissues of the temporomandibular joint (TMJ) . Because it has no harmful effects, it can be used in asymptomatic subjects. MRI and clinical findings relating to TMJs were correlated with findings relating to occlusion in 20 medical and dental students (13 women, 7 men) who volunteered to participate in our study. Subjects with clinically evident joint signs such as clicking, crepitation or tenderness on palpation also exhibited pathologic MRI findings, especially in regards to configuration, position and function of the disk, and, often, disturbances of occlusal relationships between the upper and lower teeth.

Adult↗
PubMed1995

Correlation of occlusal factors and condyle position asymmetry with signs and symptoms of temporomandibular disorders in young adults.

The role of the occlusion in the etiology and prevalence of temporomandibular disorders (TMD) has not been conclusively demonstrated. Occlusal factors and condyle position asymmetry as deduced from computed tomography (CT) axial scans were correlated with signs and symptoms of TMD in 49 young adults (mean age 24 years, range 15-33 years) with complete or almost complete dentition. A statistically significant correlation was noted between these signs and symptoms and occlusal variables describing asymmetry (the amount and lateral deviation of the slide from the retruded contact position (RCP) to the intercuspal position (IP), deviation of protrusion and asymmetry in bilateral cuspid occlusion). It seems that occlusal discrepancy can be a predisposing factor to TMD, especially when it is asymmetrically expressed.

Adult↗
PubMed1995

Wooden foreign bodies in CT. Case reports and experimental studies.

CT findings in 2 patients with a wooden foreign body in the orbital region soft tissue, and a series of CT measurements of wooden elements are presented. The wooden foreign bodies presented low HU numbers in CT and were initially interpreted as a gas collection. Different species of trees presented a large spectrum of densities, varying from the -550 HU of pine up to the +289 HU of ebony. The density of a spruce plank increased along with water-logging from -470 HU to -86 HU in 4 weeks, and peak enhancement up to 106 HU was found in the layer closest to the surface. It was concluded that a wooden foreign body in soft tissues may present CT patterns simulating materials as different as a gas bubble or a bone fragment.

Adult↗
PubMed1994

Late cranial MRI after cranial irradiation in survivors of childhood cancer.

We carried out MRI on 43 survivors of childhood cancer after different treatment protocols with or without cranial radiotherapy. They were free of disease, therapy having been discontinued 2-20 years earlier. Treatment had been for various malignancies, excluding brain tumours; 27 had received cranial irradiation for acute lymphoblastic leukaemia (ALL) or lymphoma. Two asymptomatic young women treated for ALL had falx meningiomas. White matter changes, low intensity foci (representing calcification or old haemorrhage) and heterogeneous intensity focic old haemorrhages) were seen only in patients who had undergone radiotherapy. Because of the possibility of benign, potentially curable brain tumours occurring after cranial irradiation, it may be wise to carry out occasional cranial imaging in the follow-up of these patients. No routine imaging follow-up is needed after chemotherapy alone.

Adolescent↗
PubMed1994

Clinical, magnetic-resonance imaging and surgical findings in patients with temporomandibular joint disorder--a survey of 47 patients.

The purpose of this study was to evaluate and correlate the clinical, magnetic-resonance imaging (MRI), and surgical findings in 47 patients with temporo-mandibular joint (TMJ) disorders. 51 TMJs (24 right, 27 left) were operated on, because 4 patients underwent treatment of both TMJs. The best correlation between MRI and surgical findings was noted in connection with position of the disk. This was surgically confirmed altogether in 88% of cases (45/51). The clinical diagnosis was confirmed by surgical findings in 75% of cases of anterior dislocation of the disk with reduction and 89% of cases of anterior dislocation of the disk without reduction. Bone changes noted by MRI were confirmed by surgery in 71% of cases. MRI was excellent especially relating to disk position and changes in disk morphology. The results show also that there are findings using MRI, e.g. of joint effusion, which cannot be confirmed during surgery.

Adolescent↗
PubMed1994

Temporomandibular joint findings obtained by brain MRI.

Magnetic resonance imaging (MRI) is an excellent method for examining the temporomandibular joint (TMJ). Forty-five patients, 29 females and 16 males (mean age 44, range 17-77 years), who had been referred for MRI examination of the brain were asked about their TMJ problems by questionnaire. Subjectively, 29 of the 45 were symptom-free, 11 had mild symptoms, while five experienced severe ones. Symptoms of TMJ dysfunction were correlated with MRI findings that applied to the TMJ emerging in connection with a brain MRI. This study was performed in order to obtain valuable information about the structure of the TMJs. Seven of the 29 patients who anamnestically reported no symptoms of TMJ dysfunction had changes in the configuration and/or position of the disk. In this study, MRI findings concerning the TMJ did not clearly correlate with subjective symptoms of TMJ dysfunction.

Adolescent↗
PubMed1994

Information value of magnetic resonance imaging in shunted hydrocephalus.

OBJECTIVE: To study the role of magnetic resonance imaging (MRI) in evaluating children with shunted hydrocephalus. METHODS: Sixty one asymptomatic children with shunted hydrocephalus or cystic cerebrospinal fluid collections were studied by cranial MRI. The information obtained from the images was classified into three categories: provided (1) a new diagnosis, (2) additional information, or (3) no essential new information. The findings were compared with those of the last follow up computed tomograms. RESULTS: MRI provided a new diagnosis in seven cases (11.5%), and additional information was obtained in 34 (55.7%) cases. In 20 cases (32.8%) no essential new information was obtained. MRI visualised white matter lesions and corpus callosum pathology more often than computed tomograms. CONCLUSIONS: MRI provided new important information in cases of children with shunted hydrocephalus to such an extent that it can be recommended as the primary imaging method for every child with this disorder.

Adolescent↗
PubMed1994

Decreased pituitary gland height after radiation treatment to the hypothalamic-pituitary axis evaluated by MR.

PURPOSE: To evaluate treatment-related changes in pituitary gland morphology after childhood cancer and to compare these findings with growth data. METHODS: Forty-three survivors of childhood cancer were evaluated by cranial MR imaging. Twenty-nine of the patients had received radiation therapy to the hypothalamic-pituitary axis with doses of 10 to 46 Gy. The height of the pituitary gland was measured from midline sagittal images and compared with age- and sex-matched controls. Pituitary gland heights were compared with body height standard deviation scores in patients. RESULTS: The patients who had received radiation therapy to the hypothalamic-pituitary axis had significantly smaller pituitary glands than patients in the nonirradiated group or their age- and sex-matched controls (mean, 3.5 mm versus 5.9 and 5.8 mm, respectively). They were also significantly shorter than patients in the nonirradiated group. CONCLUSION: Radiation therapy to the hypothalamic-pituitary area may lead to poor growth of the pituitary gland and short stature.

Adolescent↗
PubMed1993

Cervical intervertebral foramen narrowing and myelographic nerve root sleeve deformities.

Intervertebral foramen narrowing on plain radiographs of the cervical spine was graded from 0 (normal) to 3 according to its severity; myelographic nerve root sleeve deformity was graded from 1 to 3 in 99 consecutive patients with cervical radiculopathy. We thus examined 1118 foramina and root sleeves. Plain radiographs of 684 foramina were normal, changes of one grade were seen in 243, of two grades in 145 and of three grades in 46. Grading of myelographic root sleeves' was normal in 789, changes of one grade in 157, of two grades in 129, and of three grades in 43. The correlations between the foraminal and root sleeve changes were: full correlation in 63.9%, a difference of one grade in 27.4%, a difference of two grades in 7.4% and a difference of three grades in 1.3%. The positive predictive value of the plain radiographs for myelographic root sleeve deformities was 55.5% and the negative value 87.1%.

Adult↗
PubMed1993

Visibility of foreign bodies in soft tissue in plain radiographs, computed tomography, magnetic resonance imaging, and ultrasound. An in vitro study.

We compared conventional plain radiography, computed tomography (CT), magnetic resonance imaging (MRI), and ultrasound (US) with respect to their suitability for detecting foreign bodies in soft tissue in an in vitro model using a cow tongue to simulate orofacial soft tissues. Four samples of different sizes of fractured tooth crown, pieces of amalgam, glass, asphalt, composite, dry wood, and stone were each embedded under a 2-cm-thick flap on the caudal surface of the tongue. Plain radiographs revealed all the materials except wood, and there was some variation in the subjectively evaluated radiopacity of the materials which indicated the nature of the foreign bodies concerned. MRI proved to be the least suitable imaging method, as particles with a metallic content gave rise to powerful interference artifacts. CT and especially US proved to be suitable imaging methods for foreign-body detection in soft tissue. Amalgam produced a metallic streaking artifact in CT, which visualized wood as gas density, and depicted all the other materials as similar hyperdense masses. Ultrasound was both sensitive and specific in detecting foreign bodies in soft tissue. The particles were better defined in form and size with CT and US than with MRI or plain radiography. We conclude that when plain radiographs, history, and clinical examination fail to reveal the presence of superficial foreign bodies, US or CT can serve as an alternative method.

Animals↗
PubMed1993

Parotid gland carcinoma simulating signs and symptoms of craniomandibular disorders--a case report.

The following case involves a 33-year-old woman who received two accidental blows to her left temporomandibular joint (TMJ) region six months before her first visit to the Institute of Dentistry, University of Oulu. Both clinical and computed tomography (CT) examinations of this left TMJ strongly favored a diagnosis of craniomandibular disorders (CMD). However, a fine needle biopsy and an histopathological examination of the parotid gland established the final diagnosis as poorly differentiated adenocarcinoma of the parotid gland. The course of the disease was very aggressive developing several metastases, and the patient died 24 months after the diagnosis. The presence of facial nerve paralysis, especially in combination with cheek numbness in the parotid region, should have strongly suggested the possibility of such a malignancy.

Adenocarcinoma↗
PubMed1993

A prospective one-year follow-up study with somatosensory potentials evoked by stimulation of the median nerve in patients with cerebral infarct.

Somatosensory potentials evoked by stimulation of the median nerve (median nerve SEPs) were studied in a prospective and sequential series of 40 patients with first supratentorial and nonhaemorrhagic cerebral infarct. In 35 patients the SEPs were recorded three times during the first year after the stroke. The location of the infarcted zone was reflected in the number of detected abnormalities: most patients with infarct changes extending to the gray matter of the Rolandic cortex showed abnormalities in the median nerve SEPs, and all patients with involvement of both precentral and postcentral cortical gray matter had abnormal median nerve SEPs. In the entire patient group when both latency and amplitude abnormalities were included about half (48%) of the patients had abnormal median nerve SEPs a week after the stroke, 39% 2-3 months after the stroke and 29% about one year after the stroke. These changes were not significant. When separately surveying the changes in the numbers of latency and amplitude abnormalities the difference between the first and the third examinations was nearly significant only in the number of latency abnormalities. Furthermore, in the absolute latency and amplitude values, no significant changes could be seen within the first two-three months after the infarct; within the whole one-year follow-up period a nearly significant change was noted between the second and the third examination in only one parameter (P22 peak latency). Thus, the abnormalities in the median nerve SEPs, especially the amplitude abnormalities, were relatively permanent during the one-year period after cerebral infarct.

Adult↗
PubMed1992

White matter changes in children treated for acute lymphoblastic leukemia.

BACKGROUND AND METHODS: Twenty-seven children with acute lymphoblastic leukemia (ALL) were studied by magnetic resonance (MR) imaging after central nervous system (CNS) treatment. The children were followed by clinical evaluations and computed tomographic (CT) brain scans. Two CNS treatment techniques were used. Eleven patients received intravenous and intrathecal methotrexate; 16 patients received 18-30 Gy of cranial radiation therapy in addition to systemic chemotherapy. The time interval between the CNS treatment and MR scans varied from 9 months to 4 years 8 months. RESULTS: Four of the 27 children (15%) showed white matter changes on the MR scans attributable to therapy, but only one had hypodensity on CT. Three of the 16 children (19%) receiving radiation therapy in addition to chemotherapy had white matter changes. One of the 11 patients (9%) from the group receiving only chemotherapy did so. The difference between the two treatment groups was not significant. CONCLUSIONS: Radiation therapy or chemotherapy (alone or in combination) may have been responsible for the white matter changes. MR imaging is a sensitive detector of white matter changes in children with ALL, but its value and significance during follow-up should be assessed in well-designed longitudinal research studies.

Adolescent↗