Biomedical subjects
Publications and source records attributed to J Pyhtinen.
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.
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.
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.
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.
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.
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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.
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.
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.
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.
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%.
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.
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.
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.
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.
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Mandibular asymmetry in the frontal plane is a common finding, the left side of the mandible being more often the longer one, and a progressive trend for a more post-normal occlusion on the right side as compared to the left has been reported recently. The aim of the present work was to measure bicondylar asymmetry using computed tomography (CT) and to determine whether this is correlated with certain occlusal characteristics in young adults with no gross malformations. The subjects were 49 adults aged from 15 to 33 years, mean 24.2 years (SD 3.79 years). All of them had a complete or nearly complete dentition. The left condyle was found to be more anteriorly located on average and to be positioned closer to the skull base midline than the right condyle. The joint space between the condyle and the posterior wall of the glenoid fossa was larger on the left side. The asymmetry in bicondylar position correlated with the occlusal asymmetry. Subjects with lateral malocclusions showed a more asymmetric position of the condyles with respect to the posterior wall of the glenoid fossa. This may be of clinical importance and stresses the necessity for early correction of such malocclusions, as complete adaptation does not seem to occur in these cases.
The correlation between clinical and CT findings in cerebral tumours was prospectively studied in 1191 consecutive referrals for cerebral CT. CT revealed a mass lesion in 51 cases (4.3%): 32 neoplasms, five haematomas and one abscess. The diagnostic specificity of CT for neoplasmic tumours was 86% (32 of 37). The clinical suspicion of a cerebral neoplasm was correct in 25 cases (78%) and the clinical localisatory hypothesis was correct in 20 cases (63%) of the neoplasms. A cerebral tumour was found in 5% (11 out of 226) of patients investigated for their first seizure and in 1% (two of 207) investigated for headache without clinical signs.