Asymmetrical Brain Plasticity: Physiology and Pathology.

The brain is inherently asymmetrical. How that attribute, manifest both structurally (volumetric, cytological, molecular) as well as functionally, relates to cognitive function, is not fully understood. Since the early descriptions of Paul Broca and Marc Dax it has been known that the processing of language in the brain is fundamentally asymmetrical. Contemporary imaging studies have corroborated early observations, and have also revealed significant functional links to multiple other systems, such as those sub serving memory or emotion. Recent studies have demonstrated that laterality is both plastic and adaptive. Learning and training have shown to affect regional changes in asymmetry, such as that observed in the volume of the planum temporale associated with musical practice. Increasing task complexity has been demonstrated to induce recruitment of contralateral regions, suggesting that laterality is a manifestation of functional reserve. Indeed, in terms of cognitive function, successful aging is often associated with a reduction of asymmetrical activity. The goal of this review is to survey and critically appraise the current literature addressing brain laterality, both morphological and functional, with particular emphasis on the asymmetrical plasticity associated with environmental factors and training. The plastic recruitment of contralateral areas associated with aging and unilateral lesions will be discussed in the context of the loss of asymmetry as a compensatory mechanism, and specific instances of maladaptive plasticity will be explored.

A novel quantitative approach for evaluating contact mechanics of meniscal replacements.

One of the functions of the meniscus is to distribute contact forces over the articular surfaces by increasing the joint contact areas. It is widely accepted that total/partial loss of the meniscus increases the risk of joint degeneration. A short-term method for evaluating whether degenerative arthritis can be prevented or not would be to determine if the peak pressure and contact area coverage of the tibial plateau (TP) in the knee are restored at the time of implantation. Although several published studies already utilized TP contact pressure measurements as an indicator for biomechanical performance of allograft menisci, there is a paucity of a quantitative method for evaluation of these parameters in situ with a single effective parameter. In the present study, we developed such a method and used it to assess the load distribution ability of various meniscal implant configurations in human cadaveric knees (n=3). Contact pressures under the intact meniscus were measured under compression (1200 N, 0 deg flexion). Next, total meniscectomy was performed and the protocol was repeated with meniscal implants. Resultant pressure maps were evaluated for the peak pressure value, total contact area, and its distribution pattern, all with respect to the natural meniscus output. Two other measures--implant-dislocation and implant-impingement on the ligaments--were also considered. If any of these occurred, the score was zeroed. The total implant score was based on an adjusted calculation of the aforementioned measures, where the natural meniscus score was always 100. Laboratory experiments demonstrated a good correlation between qualitative and quantitative evaluations of the same pressure map outputs, especially in cases where there were contradicting indications between different parameters. Overall, the proposed approach provides a novel, validated method for quantitative assessment of the biomechanical performance of meniscal implants, which can be used in various applications ranging from bench testing of design (geometry and material of an implant) to correct implant sizing.

How do normals move during prolonged wheelchair-sitting?

The clinical practice for minimizing the risk of pressure sores (PS) is to relief pressures under bony prominences of immobilized patients by changing their postures frequently. The US Department of Health advises to relief sitting pressures at least every 1 hour, and every 15 minutes for individuals who are body-abled. Surprisingly, there is paucity of information in the literature concerning motion of healthy subjects during prolonged sitting, which can be compared with these recommendations. Considering that healthy individuals are able to sit for hours without suffering injuries, such information seems particularly important. Accordingly, our objective was to measure frequency of postural changes and extent of motion during postural changes among healthy subjects who sit in a wheelchair (N=10), in order to provide information that is missing in the literature of PS biomechanics. Subjects were asked to sit comfortably for 90 minutes, during which their trunk's frontal and sagittal motions and sitting pressures were measured. We found that normals change their posture every 9 +/- 6 minutes in the sagittal plane, and independently, every 6 +/- 2 minutes in the frontal plane. Shoulders, thoracic-spine and lumbar-spine frontal plane motions were 8 +/- 4 degrees , 14 +/- 7 degrees and 15 +/- 7 degrees , respectively, and sagittal trunk-thigh movement was 10.3 +/- 7 degrees . The frequency of postural changes in normals, measured herein, was higher than frequencies reported in the literature for patients who suffered PS. This small study population therefore supports the hypothesis that prolonged immobilization contributes to PS onset.

Amyloidoma of the CNS. I. Clinical and pathologic study.

We report a 32-year-old man with a 4-year history of headaches, seizures, and dementia secondary to multifocal amyloidomas in the white matter. Immunohistochemical and electron microscopic analyses suggest that the amyloidomas resulted from processing of plasma-cell-derived amyloidogenic protein by microglial cells.

Mechanical compression-induced pressure sores in rat hindlimb: muscle stiffness, histology, and computational models.

Pressure sores affecting muscles are severe injuries associated with ischemia, impaired metabolic activity, excessive tissue deformation, and insufficient lymph drainage caused by prolonged and intensive mechanical loads. We hypothesize that mechanical properties of muscle tissue change as a result of exposure to prolonged and intensive loads. Such changes may affect the distribution of stresses in soft tissues under bony prominences and potentially expose additional uninjured regions of muscle tissue to intensified stresses. In this study, we characterized changes in tangent elastic moduli and strain energy densities of rat gracilis muscles exposed to pressure in vivo (11.5, 35, or 70 kPa for 2, 4, or 6 h) and incorporated the abnormal properties that were measured in finite element models of the head, shoulders, pelvis, and heels of a recumbent patient. Using in vitro uniaxial tension testing, we found that tangent elastic moduli of muscles exposed to 35 and 70 kPa were 1.6-fold those of controls (P < 0.05, for strains /=5%). Histological (phosphotungstic acid hematoxylin) evaluation showed that this stiffening accompanied extensive necrotic damage. Incorporating these effects into the finite element models, we were able to show that the increased muscle stiffness in widening regions results in elevated tissue stresses that exacerbate the potential for tissue necrosis. Interfacial pressures could not predict deep muscle (e.g., longissimus or gluteus) stresses and injuring conditions. We conclude that information on internal muscle stresses is required to establish new criteria for pressure sore prevention.

Giant invasive intracerebral dermoid tumor with subependymoma-like reaction: case report.

A large, completely intracerebral, dermoid tumor with extensive outgrowth of appendages into brain tissue caused prominent reactive changes in the surrounding white matter, similar to those seen in a typical subependymoma. This case lends support to the notion that some subependymomas are reactive in etiology.

Spinal epidural abscess: a ten-year perspective.

A retrospective study of spinal epidural abscess spanning 10 years and encompassing 40 patients was done. Epidemiology, clinical features, laboratory findings, radiographic imaging, therapy, and outcome were examined and compared with previous series. An increasing incidence of the disease (up to 1.96 patients per 10,000 admissions per year) and an older, more debilitated population (67% having factors predisposing them to infection) were discovered. Over half of the population was studied with magnetic resonance imaging, which was found to be equally as sensitive (91%) as myelography with computed tomography (92%). Magnetic resonance imaging offers the advantages of being noninvasive and able to delineate other entities, which makes it the imaging modality of choice. Preoperative paralysis and neurological deterioration from normal were identified as poor prognostic features. Of 7 patients with preoperative paralysis, 5 died, and the rest failed to recover neurological function. Eleven patients with initially normal neurological exams deteriorated in the hospital before surgical intervention. Eight of these patients were being treated with appropriate antibiotics; 2 became paralyzed despite more than 3 weeks of antibiotic therapy. Only 3 of these 11 patients recovered fully. Immediate surgical decompression combined with antibiotics remains the treatment of choice.

Validation of object-induced MR distortion correction for frameless stereotactic neurosurgery.

Spatial fidelity is a paramount issue in image guided neurosurgery. Until recently, three-dimensional computed tomography (3D CT) has been the primary modality because it provides fast volume capture with pixel level (1 mm) accuracy. While three-dimensional magnetic resonance (3D MR) images provide superior anatomic information, published image capture protocols are time consuming and result in scanner- and object-induced magnetic field inhomogeneities which raise inaccuracy above pixel size. Using available scanner calibration software, a volumetric algorithm to correct for object-based geometric distortion, and a Fast Low Angle SHot (FLASH) 3D MR-scan protocol, we were able to reduce mean CT to MR skin-adhesed fiducial marker registration error from 1.36 to 1.09 mm. After dropping the worst one or two of six fiducial markers, mean registration error dropped to 0.62 mm (subpixel accuracy). Three dimensional object-induced error maps present highest 3D MR spatial infidelity at the tissue interfaces (skin/air, scalp/skull) where frameless stereotactic fiducial markers are commonly applied. The algorithm produced similar results in two patient 3D MR-scans.

Intracranial abscesses secondary to nasal, sinus, and orbital infections in adults and children.

Nineteen cases of intracranial abscesses secondary to infection of the midface are reported. The most common underlying cause was bacterial sinusitis. Other etiologic factors included mucormycosis following steroid therapy, Wegener's granulomatosis, nasal dermoid cyst and sinus tract, tooth abscesses, aspergillosis following chemotherapy for leukemia, squamous cell carcinoma of the frontal sinus, infected methylmethacrylate plate for a prior skull fracture, and a case of gauze packing left in the sinus following surgery. Anaerobic organisms were the predominant cause of the abscesses. The most dangerous intracranial complication was subdural abscess, which occurred in seven patients in this series. Three of them died. Four cases of frontal and parietal lobe abscesses were treated with systemic antibiotics only. This approach has not been well emphasized in our literature. Steroid therapy should not be used for the treatment of sinus and orbital infections. It can result in dreadful complications. The overall mortality rate in this series was 21% (4 of 19), despite aggressive treatment and close cooperation between the neurosurgeon, otolaryngologist, and other specialists. Early diagnosis and adequate treatment are paramount.

Computed tomography demonstration of multiple parenchymal central nervous system nodules due to histiocytosis X.

The computed tomography demonstration of multiple parenchymal brain lesions due to histiocytosis X is described. A comparison of follow-up computed tomography and magnetic resonance imaging studies is made.

Intracranial pressure gradients in a patient with a thalamic tumor.

The clinical history and intracranial pressure records of a patient with a thalamic tumor obstructing the ventricular system is presented. There were sustained differences in pressure between the anterior and posterior parts of the obstructed lateral ventricle. Brain compliance was markedly reduced and there were numerous pressure waves. It is believed that these supratentorial pressure gradients are most marked when there is a loss of brain compliance, and that they contribute to the mechanisms of brain shifts and spreading edema. Thus, they must be taken into account in the management of patients with intracranial mass lesions.

[Liposarcoma of the spermatic cord]. / Liposarcoma del funicolo spermatico.

A case of well differentiated liposarcoma of the spermatic cord in a 80 year old man is presented. The preoperative diagnosis of spermatic cord liposarcoma is not easy; however, a careful comparison between clinical and ultrasonographic findings can lead to diagnostic suspicion. The treatment of choice is the excision of the liposarcoma associated with orchiectomy and high ligation of the spermatic cord to reduce the risk of recurrence. Postoperative radiotherapy may be indicated for poor differentiated liposarcomas.

[Ventrolateral hernias of the abdominal wall. The anatomicopathologic, clinical and therapeutic considerations]. / Le ernie ventro-laterali della parete addominale. Considerazioni anatomopatologiche, cliniche e terapeutiche.

Ventral lateral hernias of the abdominal wall are rare. On the basis of their location we can classify them as follows: hernias of the aponeurosis of the transversus muscle, hernias of the rectal sheath and transmuscular hernias of the iliac region. In a group of 3134 hernias of the abdominal wall observed in a period of 16 years, 11 ventral lateral hernias have been encountered (0.3%). The diagnosis often presents great difficulties as the symptoms and the clinical findings are not typical. They must be differentiated from hematomas of the rectus sheath, abscess or intra-abdominal processes. Echography and Computed Tomography have an important role in their detection. Nevertheless in some patients the true diagnosis is reached only intraoperatively. The treatment generally consists in surgical correction by layer closure of the fascial or muscular defect. In selected cases the use of prosthetic material and video laparoscopic repair are indicated.

[Myofibroblastoma of the male breast. Apropos of a case]. / Miofibroblastoma della mammella maschile. A proposito di un caso.

A case of male breast myofibroblastoma, personally observed, is described. Preoperative examinations have a limited diagnostic value. Only histological study, with immunohistochemical stain, allows to make a right diagnosis and to distinguish this tumor from other, benign or malignant mesenchymal neoplasms.

[Primary lymphoma of the breast. Three cases of non-Hodgkin lymphoma]. / Il linfoma primitivo della mammella. A proposito di 3 casi di linfoma non-Hodgkin.

Primary and sole breast lymphoma is a very rare disease. With the review of our series of 616 cases operated on for breast cancer, only 3 cases (0.48%) of primary breast non-Hodgkin lymphoma (LNH) have been observed. The authors outline the problems concerning diagnosis and therapy of this rare disease: pathological and immunohistochemical aspects are discussed. They stress the importance of staging in order to plan a correct multidisciplinary approach.

[Our experience in the surgical treatment of early breast cancer. Results of a prospective study of 204 cases]. / La nostra esperienza nel trattamento chirurgico del carcinoma mammario iniziale. Risultati di uno studio prospettico su 204 casi.

The authors report the results of a prospective study on 204 patients (1980-1993) affected by early infiltrating breast cancer (size pounds 2 cm) as a part of a surgical series of 608 cases. 53 cases who underwent QUART (25.9%) and 151 cases (74.1%) who underwent mastectomy modified according to Patey have been collected. 10 years actuarial survival has been respectively 79% after extensive surgery and 78% after conservative treatment. Local recurrences have been observed in 9 cases after meticulous follow-up (median 74.8 months, range 12-178): 3 (5.66%) patients after QUART and 6 (3.97%) after mastectomy; furthermore 1 patients after a conservative treatment (1.88%) has developed a second tumor at the same side probably dependent on the presence in the primary tumor of an extensive intraductal component. No correlations between histological features, grading, positive nodes, receptor status and local recurrences have been found. Only the age of patients looks significantly correlated with frequency of recurrences: 44.45% of local recurrences have been observed in patients less than 45 years old. Local recurrences after QUART have obliged, in all cases, to a radical mastectomy. Furthermore, frequency of distant metastases has been considered: after QUART percentage is lower (9.43%) than after radical mastectomy (13.9%). This consideration looks correlated with the longer follow-up of the later group. A multidisciplinary approach is advised but the most important role is played by surgery. In conclusion it is outlined that conservative surgery is addressed to selection and consenting patients.

[Natural history of breast cancer: lobular carcinoma versus ductal carcinoma in our experience]. / A proposito della storia naturale del cancro della mammella: carcinoma lobulare versus carcinoma duttale nella nostra esperienza.

Aim of the study is to evaluate the biology, the clinical evolution and the prognosis of lobular carcinoma of the breast. We retrospectively evaluated the patients treated in our institution during the last 13 years. 117 patients with lobular carcinoma of the breast and 117 patients, randomized out of 397 patients with 'classical' pattern of ductal carcinoma were compared. Age distribution, type of surgery, tumor size, TNM stage, axillary lymph node involvement, multifocality, multiple breast cancers, local and distant recurrences, overall survival and disease-free survival have been evaluated. There was not a significant difference in tumor size, lymph node involvement, stage distribution, estrogens and progesterone receptors status, local and distant recurrences. The only significant differences were found in multifocality and multiple breast cancers. The said difference does not seem to modify the overall survival and the disease-free survival that are the same in the two groups. Our research shows that tumor size and axillary lymph node status are the only elements that have to be considered in the choice of the surgical treatment and prognosis. It seems that the difference in distant metastatic pattern between lobular and ductal carcinoma is the distinctive feature in the follow-up of these patients.