Khang-Cheng Ho

Progressive and regressive changes in the nucleus pulposus. Part II. The adult.

The spines of 28 cadavers were studied with magnetic resonance (MR) imaging, correlated with anatomic sections, to characterize the progressive and regressive changes in the nucleus pulposus. Four additional types of nucleus pulposus were identified in this study. The transitional type (type II) of childhood had fibrous tissue that developed near the anulus fibrosus anteriorly or posteriorly. MR images showed a notch of reduced signal intensity in the nucleus pulposus where the fiber was developing. The adult type (type III), which is predominant after age 30 years, had an indistinct boundary between the nucleus pulposus and anulus fibrosus. MR images showed the fibrocartilage in the nucleus pulposus and inner anulus fibrosus as areas of high signal intensity. Adult disks with a tear of the anulus fibrosus (type IIIB) had a lower signal intensity on MR images and slightly reduced disk heights. This type may represent an early stage of degeneration. Degenerated intervertebral disks (type IV) had either dense disorganized fibrous tissue or fluid replacing the normal fibrocartilaginous structure of the nucleus pulposus. MR images showed narrow intervertebral disk spaces with either reduced signal intensity if collagen was present or increased signal intensity if fluid was present. This study suggests that the nucleus pulposus may progress normally through types I, II, and III.

Lateral Supratentorial Endodermal Cyst: Case Report and Review of Literature

OBJECTIVE AND IMPORTANCE Epithelial cysts of the central nervous system are unusual entities, with the majority reported to occur in the spinal canal. More unusual is the intracranial presentation, which shows a predilection for midline localization in the posterior fossa, brainstem, and suprasellar regions. This report discusses the differential diagnosis, pathogenesis, radiographic presentation, and therapeutic considerations of a laterally positioned cerebral convexity endodermal cyst. CLINICAL PRESENTATION A 49-year-old right-handed man presented with approximately a 30-month history of short- and long-term memory difficulties. A magnetic resonance imaging study revealed a large, nonenhancing, extra-axial cystic lesion overlying the right lateral frontal convexity. INTERVENTION A right frontoparietal craniotomy exposed a large extra-axial cyst with an opaque, yellowish-white membrane containing a mucoid fluid. Histological analysis disclosed a layer of unremarkable, ciliated columnar epithelium with a basement membrane that stained positive for cytokeratin, periodic acid-Schiff, and Alcian blue. No evidence of either a muscular or cartilaginous layer around the mucosa was present to further delineate neurenteric versus bronchogenic origin of the cyst. CONCLUSION This case involved the occurrence of a solitary endodermal cyst as an extra-axial mass localized over the lateral frontal lobe. The lateral supratentorial localization of this lesion illustrates the need for consideration of the pathogenesis of this entity as well as its diagnostic differentiation from other cystic abnormalities in this region. A review of the histochemistry of endodermal, neuroepithelial, and other cerebral cysts is presented.

Fulminant progression of demyelinating disease after valproate-induced encephalopathy

We report the clinical, radiologic, and pathologic features of a patient who had fulminant demyelinating disease and who experienced acute progression of his disease after an episode of valproate-induced hyperammonemic encephalopathy. The role hyperammonemia played in the progression of the demyelination is uncertain. This case raises concern of a possible risk with the use of valproic acid in the subset of patients with fulminant demyelinating disease.

Experimental production of arachnoiditis with water-soluble myelographic media.

After myelography with either metrizamide (300mg l/ml) or meglumine iocarmate (280 mg l/ml), mild to severe arachnoid fibrosis was demonstrated radiographically and histologically in primates. Intrathecal injections of metrizamide (170 mg l/ml) or autologous cerebrospinal fluid produced less arachnoiditis. The risk of arachnoiditis is probably minimized by the use of reduced volumes and concentrations of water-soluble media. Controlled studies of arachnoiditis following myelography are probably more reliable in the primate model than in other experimental animals.

Chemodectoma involving the cavernous sinus and semilunar ganglion

This paper reports a case of paraganglioma involving the cavernous sinus and semilunar ganglion. The origin of the tumor cells, from paraganglia in this region, is also discussed. Recognition of paraganglia in this area may aid the clinician and pathologist in the differential diagnosis of tumors in this region.

Progressive multifocal leukoencephalopathy and malignant lymphoma of the brain in a patient with immunosuppressive therapy.

SummaryProgressive multifocal leukoencephalopathy and malignant lymphoma of the brain were noted at postmortem examination in a 68-year-old white woman who was treated with immunosuppressive agents after renal transplantation. The two diseases are not uncommon in patients with immunodeficiency, but their occurrence in the same patient is extremely rare. This association suggests the oncogenicity of papova viruses in man. However, no papovavirus was demonstrated in the tumor by electron microscopy and immunohistochemical staining. The immunohistochemical staining of routine histologiy sections for the common antigen of polyomaviruses by the peroxidase anti-peroxidase technique is shown to be simple and specific for the detection of polyomaviruses in the demyelinated areas of progressive multifocal leukoencephalopathy.

Gadolinium-enhancement characteristics of magnetic resonance imaging in distinguishing herniated intervertebral disc versus scar in dogs.

Study Design This study is an experimental investigation on the gadolinium contrast magnetic resonance imaging (MRI) in distinguising sequestered disc fragment versus scar in dogs. The conspicousness of the disc fragment and signal intensities of the disc fragment and signal intensities of the disc fragment and I am inectomy scar were evaluated using gadolinium-enhanced MRI and histology. Objectives This study investigated the effects of timing of gadolinium injections, gadolinium doses, and aging of scar or disc on the enhancement characteristics and conspicuousness of disc fragment in MRI. Summary of Background Data Contrast-enhanced MRI has been frequently used as a procedure to evaluate patients with suspected recurrent herniated discs. in contrast-enhanced MRI, the postoperative scar tissue enhances to a greater extent than disc fragments, Previous reports suggest different contrast enhancement characteristics of scar depending on doses, timing of gadolinium, or maturity of scar. There are different compounds of gadolinium agents and different doses are becoming available. There is no previous report on the evaluation of gadolinium enhancement characteristics in dogs with concurrent herniated disc and scar. Methods Six conditioned Beagle dogs underwent hemilaminectomies and discectomies at the L3-L4 level. An autogenous disc fragment was obtained from the intervertebral disc of the tall. This disc fragment was placed anterolateral to the thecal sac, simulating a sequestered disc herniation. Three control animals underwent hemilaminectomies and discectomies alone. Each dog underwent MRI on a 1.5 Tesla scanner (3.0 mm slice in sagittal and axial projections with TR 500, TE 30 msec and high dose 0.3 mmol/kg of gadoteridol). images were obtained at 15 days, 30 days, 60 days, and 90 days after surgery. At each imaging session, contrast enhancement was measured at 2 minutes, 25 minutes, and 45 minutes after gadolinium injection for kinematic analysis. Two animals at a time were killed on 30 days, 60 days, and 90 days postoperatively. Magnetic resonance Imaging was done with conventional low dose 0.1 mmol/kg of gadopentetate at 15 days and before death. Results Results revealed that the difference of enhancement between disc and the scar and the refore conspicuousness of disc fragment was greater on 2–23-minute images as compared with 45− minute images, and the distinction decreased with aging of the scar. The high dose contrast-enhanced MRI increased signal intensities for both disc and scar, Conspicuousness of disc fragment seemed to be better with the high-dose gadolinium compound. Conclusions In conclusion, contrast enhancement characteristics in MRI may depend on the timing of MRI after gadoilinium injection, doses of gadolinium, and aging of scar or disc.

The etiology of focal spinal arachnoiditis : an experimental study

Focal arachnoiditis and back pain have been attributed to potentially irritating substances leaking into the spinal canal from the lumbar intervertebral disc or facet joints. Through experimentation this hypothesis was tested: the nucleus pulposus (escaping from the intervertebral disc), lactic acid (from anaerobic glycolysis in the disc), chondroitin sulfate (a component of glycosaminoglycans in the disc), or synovial fluid (from degenerating facet joints) causes inflammation in the meninges if it contacts the dura mater. The test and control substances were injected into the epidural space of monkeys. Twelve weeks later the animals were killed; the dural sac was exposed by total lumbar laminectomy, grossly inspected, and then removed, fixed, sectioned, stained, and examined microscopically. Nucleus pulposus produced significant fibrosus in the arachnoid and epidural spaces; the other substances did not cause fibrosus or inflammation. The study suggests that leakage of nucleus pulposus into the epidural space causes an inflammatory response in the arachnoid and epidural spaces.

Correlation of neuronal cell body size in motor cortex and hippocampus with body height, body weight, and axonal length

This study examined the comparative effects of body height and body weight on the neuronal cell size in humans and investigated their possible mechanisms. A total of 21 cases between the ages of 20 and 40 years were studied. Data on body height, body weight, and neuropathology were obtained from autopsy records. Mean cross sectional areas of cell bodies for 30 normal neurons were determined for the motor cortex projecting to lumbar spinal cord segments (L) 1-4 (Betz cells) as well as various regions of the hippocampus. Approximate axonal length of the motor neuron studied was measured from motor cortex to L2. We found that only motor cortex neuronal cell body size was significantly proportional to body height and the respective axonal length (p < .05). The findings indicate that: 1) body height has a greater effect than body weight on the motor neuron cell size, probably because of its association with axonal length; 2) the effect is regional (motor cortex) rather than general.

Arachnoiditis Following Myelography with Water-Soluble Agents: The Role of Contrast Medium Osmolality

The role of contrast medium osmolality in postmyelographic arachnoiditis was studied. Monkeys were injected intrathecally with isotonic saline (290 mOs/kg), hypertonic saline (1,449 mOs/kg), metrizamide (456 or 300 mOs/kg), or methylglucamine iocarnate (1,049 mOs/kg). After 12 weeks the animals were examined for evidence of arachnoiditis, with myelography just prior to sacrifice and microscopic examination of the excised dural sac and its contents. Intrathecal injections of methyglucamine iocarmate or metrizamide caused arachnoiditis while saline did not. Only one animal given 170 mg l/ml (300 mOs/kg) exhibited a more severe reaction than the controls. An increase in the cerebrospinal fluid osmolality alone does not cause arachnoiditis.