Hyperparathyroidism after radioactive iodine therapy for Graves disease.

The association of external ionizing radiation to the head and neck and the subsequent development of hyperfunctioning parathyroid glands has been documented in recent years. This also has been demonstrated experimentally in animals. Despite the numbers of patients with Graves disease who have been treated with radioactive iodine, there are no reports in the literature of parathyroid surgery for hyperparathyroidism secondary to earlier treatment with radioactive iodine for Graves disease. This report describes the operative and pathologic findings in four patients with hyperparathyroidism. These patients had previously been treated with radioactive iodine for Graves disease. The pathologic findings at surgery included in three cases a single enlarged hyperplastic gland consistent with a parathyroid adenoma. One patient had hyperplasia of all four glands. The two largest glands and halves of the two remaining glands were removed. In a long-term follow-up of children and adolescents treated with radioactive iodine for Graves disease, Levy and Schumacher found calcium elevations in 10 of 159 patients. The increased incidence of hyperparathyroidism following radioactive iodine treatment for Graves disease in children and adolescents would seem several times higher than normal. Whether adults who have radioactive iodine treatment for Graves disease have a similar increase incidence is not known. Meanwhile it would seem reasonable to suggest that patients whose hyperthyroidism is treated with radioactive iodine should have their serum calcium levels determined at 5-year intervals.

A method for in vitro enzymatic dissociation of nerve roots and peripheral nerves from adult mammals.

Preparations yielding a high percentage of undamaged axons from fresh peripheral nerve or nerve root were made using an enzymatic dissociation regimen. The nerve was placed in a temperature-controlled chamber mounted over an inverted phase-contrast microscope. An oxygenated solution (Brimijoins) or modified Hank's solution was pumped through the chamber, first in a calcium-free form and then containing enzymes. The enzymes for dissociation were collagenase and trypsin, alternated. Enzymatic dissociation of the epineurium, perineurium and extracellular matrix was achieved. We supplemented the gentle agitation of a 10-roller peristaltic pump by periodically raising and lowering the fluid level in the chamber to provide a controlled mechanical agitation that promoted dissociation. A large percentage of the axons can be dissociated from the nerve, varying from approximately one-quarter to occasional complete dissociation. Action potentials were still conducted through dissociated axons, and axon transport was also still present, as documented by direct visualization using an AVEC-DIC type of microscope system. The axons had a better morphological appearance and displayed better transport than comparison preparations prepared by the usual mechanical teasing method, in our hands. The enzymatic method allows study of axons in an adult or developing mammal with regard to their electrical conduction and axon transport mechanisms. It should help to avoid a selection process for more hardy axons which may be imposed by traditional mechanical teasing methods. Mechanical stress was observed to cause widened Schmidt-Lanterman clefts, widened nodes, myelin bubbles, and other abnormal morphology as evidence of damage.

Focal magnetic coil stimulation reveals motor cortical system reorganized in humans after traumatic quadriplegia.

A figure of '8' magnetic coil (MC) was used to stimulate focally the motor cortex of two adult, traumatic quadriplegics and three normal adults. The two patients were injured approximately 2 years previously and had intense physiotherapy, including biofeedback training of biceps and deltoid muscles, respectively, which were the most caudal muscles spared. The focal MC elicited compound motor action potentials (CMAPs) from these muscles from a much wider area of scalp than in the normal subjects. Latency of biceps and deltoid CMAPs were inversely related to CMAP amplitude. A reorganization of the motor cortical projection system is inferred, in which areas normally eliciting digit movements instead activate muscles in quadriplegics just above the spinal level. The reorganization applies also to the central sense of movement normally elicited by focal frontal cortex stimulation. Possible mechanisms of the reorganization and an implication for rehabilitation are discussed.

Peripheral nerve repair across a gap studied by repeated observation in a new window implant chamber.

We have developed a new peripheral nerve chamber system which allows high resolution observation of the cellular events involved in nerve regeneration. The growth into the chamber is confined to a two-dimensional sheet resembling tissue culture. An intact blood supply forms within the chamber and by 100 days the nerve bridging the chamber has a nearly normal perineurium surrounding unmyelinated and myelinated axons. Degenerating axons are very rarely seen. The early growth in the chamber has a tendency to spread widely and form a two-dimensional sheet. This results in morphologies similar to those found in tissue culture and facilitates observation of individual elements. The initially wide tissue growth gradually re-models to form a bridge with a constant width similar to the width of the peroneal nerve. Occasionally a 'side arm' containing myelinated axons was retained even though the majority of axons appeared to loop back and rejoin the main bridge. Prefilling the chamber with Matrigel did not produce a significant enhancement of growth rate over that found following prefilling with sterile saline but did result in a more normally organized structure in the long term. Proximal ingrowth occurred at a similar rate in the absence of the distal stump. The structure of the proximal stump in the absence of the distal stump was similar to the structure when both stumps were present, including the presence of myelinated axons near the proximal port by 20 days. However, at subsequent stages the absence of a distal stump led to withdrawal of the proximal growth.

Proposal for bipolar coagulation of the sella turcica wall during pituitary tumor operation.

Convoluted morphology, limited visualization, and the lack of appropriate instruments limit the surgical approach to the walls of the sella turcica. They are, however, a site of local invasion and retained tumor fragments in cases of pituitary lesions. Effective bipolar coagulation within the sella turcica could reduce recurrence from local invasion, but it is made difficult because rigid bipolar forceps cannot fit effectively or safely against the complex contours of the walls there. Effective coagulation and thorough tumor removal are further frustrated by the lack of direct visualization of either the sella walls or the part of the floor adjacent to the surgical opening. It would be desirable, however, to coagulate the dura mater and retained tumor fragments. As an aid in this problem, we are reporting the use of a flexible bipolar coagulation system in two forms and of a mirror system for visualization in the sella without requiring the removal of one hand from surgical maneuvers. A pair of parallel flexible wire extensions to the standard bipolar forceps can be shaped by the surgeon into a contour that will coagulate the specific local terrain. A web of wire woven into one surface of a cotton patty, which is a bipolar coagulation system, supplements the wire loops. This allows the walls of the sella turcica to be coagulated more effectively where the contours are difficult to gauge and not well visualized. For visualization of the sella turcica walls and floor, we have used a small front surface mirror 1.0 mm thick.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical experience with motor and cerebellar evoked potential monitoring.

We are reporting 98 cases of motor evoked potential (MEP) monitoring performed between 1982 and 1986. These were divided into supratentorial, posterior fossa, and spinal cord categories. We observed in this sample that the peripheral nerve or electromyographic response was substantially more sensitive than the spinal cord response to injury and hypotension during operation and was often present bilaterally. Reversible weakening or loss of the peripheral nerve response was not associated with a deficit. However, weakening of the peripheral nerve response without recovery could warn of a motor defect after operation. The spinal cord responses can change so little in amplitude and latency with injury conditions that their reliable use during operation without accompanying peripheral nerve and muscle response monitoring may be compromised, especially in view of the often difficult recording environment in the operating room. With spinal cord monitoring, the MEP seemed closely correlated with the stresses that we imposed on the cord, as well as with subsequent clinical outcome. In posterior fossa cases, we observed sensitivity of the MEP to manipulation of the nervous system and reliable indication of the outcome in the cases monitored. Supratentorial cases present a more complex environment for monitoring; a potential pitfall is to stimulate an area that produces responses in the peripheral nerves and spinal cord, but that is not being compromised by the injury process. Alternatively, stimulating too large an area of cortex or stimulating with too high a current, which penetrates to white matter below the gray matter, may not show an injury. Although we did not encounter cases where permanent deficits were missed by the motor evoked potential, we were concerned by the appearance of temporary deficits. These may be related to technical limitations of our methods and indicate that monitoring of the supratentorial process requires substantial methodological advance for high reliability. Modulation of the MEP by prior somatosensory evoked potential stimulation seems useful and promising. Cerebellar evoked potential responses were present in humans and were sensitive to injury. Overall, this test is promising.

Simple plastic stereotactic unit for use in the computed tomographic scanner.

The marriage of computed tomography (CT) and stereotactic surgery offers an opportunity to provide sophisticated and effective treatment to discrete areas of the brain. An important part of this capability is the development of stereotactic frames that are compatible with the CT scanner, i.e., that do not degrade the CT image. A number of technically elegant and ingenious stereotactic frames have been reported. However, they have the drawback of technical complexity and, particularly, great exposure. We are reporting a simple ball and socket skull-mounted stereotactic device that allows solid fixation of probes for use in brain needle biopsies, ventricular catheterization, and similar activities.

Curved biopsy needle for stereotactic surgery: a technical note.

Needle brain biopsy and aspiration is an important technique for the diagnosis of tumors and for the evacuation of fluid collections. Current biopsy methods use a straight needle, which has the disadvantage of requiring multiple passes through the overlying brain to obtain multiple biopsies. Furthermore, a straight needle does not give optimal samples of tumor for diagnosis because the needle passes through the viable rim of the tumor instead of along it. We are reporting a curved plastic biopsy needle suitable for computed tomography-guided biopsy. It remains inside an outer guide catheter that holds it straight until it reaches the edge of the tissue to be biopsied. At this point, the needle is advanced beyond the guide catheter and obtains the biopsy sample by passing around the edge of a tumor. This can in principle produce an improvement in diagnostic yield. Furthermore, multiple biopsies of the tumor from a single guide catheter position are possible. The surgeon rotates the curved needle within its guide catheter to redirect it before the needle emerges, and a different biopsy is then obtained without reinsertion. This avoids multiple punctures of the overlying uninvolved tissue. We are reporting the technique and beginning an evaluation of it.

Evoked potentials from the motor tracts in humans.

Spinal cord monitoring during operation is of increasing importance in the prevention of injury. However, there is no direct monitor of the motor tracts available. We have reported a system using direct stimulation of the area overlying the motor tract between the intermediolateral sulcus and the dentate ligament in cats. This produces a 100-m/second signal with later components, which is abolished by section of the motor area, but not by section of the dorsal columns or the anterior quadrant of the spinal cord. Such stimulation also produces motor movement when the correct frequency is used. We now report the first application of this technique in humans, in whom we found the same 100-m/second signal, as well as slower components. We were able to elicit distal limb motor movement with stimulation of the motor tract area, but not with stimulation of the dorsal column area. This technique can be used either in open surgical cases or percutaneously and should provide an additional valuable technique for assessing spinal cord function.

Chiari malformation presenting in adults: a surgical experience in 127 cases.

We reviewed 127 patients who were operated upon for adult presentation Chiari malformation and made six conclusions: (a) The clinical examination remains crucial in the diagnosis. (b) The surgical anatomy is highly varied. (c) Syrinxes can be missed on preoperative contrast studies. (d) By a conservative grading system, we determined that 46% of the patients improved during long term follow-up. One-quarter deteriorated over the long run in spite of any treatment. (e) The overall results did not differ whether the treatment was plugging of the central canal plus decompression or decompression alone. (f) In patients with progression, plugging of the central canal obtained superior results. A review of the literature shows that the natural history of this complex disease process has not been established. This history is needed to identify the course of what may be several important factors that lead to the pathological condition in this disease.

Motor evoked potential as a predictor of recovery in chronic spinal cord injury.

In injury to the spinal cord, motor function is the most critical system affected. The introduction of motor evoked potential (MEP) monitoring techniques over the past 5 years has opened new possibilities for the assessment of motor function. We examined the MEP change in 30 cats that received weight drop injuries to the thoracic spinal cord and correlated it with function. The MEPs were recorded above and below the injury and in the sciatic nerves. In these animals, we found that the peripheral nerve response to the MEP was the most sensitive to injury, disappearing immediately upon weight drop. The MEP at the spinal cord level was somewhat more sensitive to injury than the SSEP at the cord level, and the SSEP at the cortex was the least sensitive to injury. The MEP spinal cord signal below the lesion showed both a latency increase and a substantial amplitude decrease after impact. The latency increase, however, was of relatively small absolute magnitude making the amplitude change easier to monitor. The animals were followed chronically, and 17 of the 30 regained ambulation. In all animals (followed up to 2 months), the peripheral nerve signals returned at or immediately before the time of ambulation. In none of the animals who failed to regain a peripheral nerve response was ambulation attained. This supports a strong correlation of the peripheral nerve response with walking. However, the peripheral nerve response was only a short term predictor. Examination of the spinal cord signal showed that the MEP spinal cord signal below the lesion as a percentage above the lesion was a significant correlate of current ambulation recovery, with a correlation coefficient of 0.55. This suggests that evaluation of the SSEP and MEP spinal cord signals may be able to predict longer term recovery in animals and perhaps humans.

Comparison of laser and radiofrequency dorsal root entry zone lesions in cats.

Dorsal root entry zone lesions are effective in the control of intractable pain in several types of spinal cord injuries. Traditionally, these lesions have been made with the radiofrequency technique. This is effective, but has the drawback of being laborious, and there is a significant incidence of permanent weakness. We have evaluated the carbon dioxide laser, hoping that it would be both faster and more controlled, thereby offering the chance to lower the complication rate. In comparing a parallel series of radiofrequency and laser dorsal root entry zone lesions along the cat's spinal cord, we observed that the radiofrequency lesion was larger. In addition, it had 3 times more variability in its size than the laser lesion. We attribute this in part to the nature of the laser in making a very precise and reproducible lesion. Second, the extremely brief pulse of the laser, a fraction of a second, means that movement of the spinal cord from respiration and heartbeat and movement of the surgical instrument from the surgeon's hand become far less important in inducing lesion variability. We also studied for 2 months a series of chronic cats; there were no complications due to the laser. This work suggests that the laser is a useful instrument for dorsal root entry zone lesions, but requires more precise aiming and focusing.

Primary malignant nerve sheath tumor of the gasserian ganglion: a report of two cases.

Primary tumors of the gasserian ganglion are usually benign, and secondary tumors are malignant. We report two cases of a malignant primary tumor of the gasserian ganglion, bringing the total in the world literature to five. The presentation, etiological features, and treatment of these cases are reviewed, together with a review of the literature. Preoperative differentiation from a benign tumor is not possible with certainty. A combination of operation and radiation therapy seems to be the best treatment at present.

Model for the study of individual mammalian axons in vivo, with anatomical continuity and function maintained.

Methods for the study of axons involve whole nerve preparations, teased preparations of axons that are excised from their proximal and distal connections, and tissue culture models. As a complement to these, it would be advantageous to study separated, isolated axons in vivo, still in continuity with the end organ distally and the spinal cord central nervous system neuron proximally. This would allow the study of axon function, normal or pathological, in a close relationship to its biological environment. To achieve this, we have passed the surgically isolated sciatic nerve of a rat through a chamber specially designed for enzymatic dissociation. This was based on principles derived from a prior in vitro method for dissociating nerve into axons. The chamber has controlled temperature and flow and is on an inverted microscope stage, allowing observation of the process. We perfused the chamber with a calcium-free solution followed by a series of enzymes: collagenase, trypsin, and hyaluronidase. This dissociates that part of the extracellular matrix external to the Schwann cells, leaving free, myelinated axons with their Schwann cells. In this acute preparation, the axons continue to conduct action potentials for at least 8 hours. Furthermore, an in vitro study of the axon after the in vivo dissociation demonstrated that axonal transport was maintained in over 90% of the axons, directly visualized on an AVEC-DIC type of microscope system. Properties of axonal transport or active spike propagation can thus be studied individually in an in vivo axon preparation.(ABSTRACT TRUNCATED AT 250 WORDS)

Needle biopsy of intrancranial lesions guided by computerized tomography.

Biopsies can be performed directly with computerized tomography (CT) head scanners with some difficulty. The small scanning orifice does not allow enough room for needle placement; therefore, biopsy is difficult. In contrast, the scanning orifice of the CT body scanner is large enough to permit biopsies without hindrance. Over 300 CT-guided abdominal biopsy procedures have been performed at the Cleveland Clinic Foundation. We are reporting the technique and the results of 14 CT-guided brain biopsies. There were no complications in the series and an accurate diagnosis was made for 13 of the 14 patients.

Central cord syndrome as a delayed postoperative complication of decompressive laminectomy.

We report five cases of a central cord syndrome that appeared as a delayed surgical complication several days after decompressive laminectomy with the patient in the sitting position. Some episode of abnormal positioning of the neck or hypotension seems to have triggered the central cord syndrome. The patients improved slowly, but did not return to their immediate postoperative status. This complication probably can be avoided with careful mobilization after operation, with the avoidance of hypotension, and with the use of a firm collar during the first few postoperative days.

Motor evoked potentials from transcranial stimulation of the motor cortex in cats.

Electrical testing of central nervous system pathways is assuming increasing importance in clinical medicine. However, there is no direct monitor of the motor system. We previously reported using a motor evoked potential created by direct excitation of the spinal cord, placing a stimulating electrode over the corticospinal tract area. To produce a less invasive test, we now use direct transcranial stimulation of the motor cortex through the scalp or direct stimulation of the motor cortex itself during operation. A descending signal can be recorded over the spinal cord and in the peripheral nerves where no retrograde sensory signals should be able to descend. This motor cortex stimulation produces contralateral limb movements and selective activation of the peripheral nerves of a limb. The characteristics of this signal are similar to those described in the neurophysiological literature for a descending motor signal. With a depth electrode, it was found that the signal was strongest in the spinal cord near the corticospinal tracts and in the anterior horn cell area. A set of lesioning studies showed that most of the signal travels in the area of the corticospinal tract, with some traveling in the ventral portion of the spinal cord, perhaps in the anterior corticospinal tract. Section of the pyramid essentially abolishes the signal, but lesioning of the red nucleus does not. This test offers an electrical assessment of the motor system that can be useful in experimental work on spinal cord and brain function. It has potential clinical applicability in humans.

Motor evoked potentials from transcranial stimulation of the motor cortex in humans.

Electrical monitoring of the motor system offers the potential for the detection of injury, the diagnosis of disease, the evaluation of treatment, and the prediction of recovery from damage. Existing evoked potentials monitor one or another sensory modality, but no generally usable motor monitor exists. We have reported a motor evoked potential using direct stimulation of the spinal cord over the motor tracts in cats and in humans. To achieve a less invasive monitor, we used transcranial stimulation over the motor cortex in the cat, thus stimulating the motor cortex. We report here the initial application of this method to humans. A plate electrode over the motor cortex on the scalp and a second electrode on the palate direct a mild current through the motor cortex which will activate the motor pathways. This signal can be recorded over the spinal cord. It can elicit contralateral peripheral nerve and electromyographic signals in the limbs or movements when the appropriate stimulation parameters are used. In clinical use to date, this has been more reliable than the somatosensory evoked potential in predicting motor function in patients where the two tests differed. It offers a number of possibilities for the development of valuable brain and spinal cord monitoring techniques, but requires further animal studies and clinical experience. Studies to date have not demonstrated adverse effects, but evaluation is continuing.

Nonpyramidal motor activation produced by stimulation of the cerebellum, direct or transcranial: a cerebellar evoked potential.

There is a need to monitor the functional status of the motor pathways well enough to predict the state of that function during operations and in injured or diseased patients. We previously reported that a motor evoked potential (MEP) can be produced by direct or transcranial stimulation of the motor cortex in both cats and humans. This signal descends through both the dorsolateral and ventral spinal cord and is primarily localized in the pyramidal tracts, producing a peripheral nerve signal and an electromyogram (EMG) response. It is more sensitive to injury than the somatosensory evoked potential (SEP). We report here that one can stimulate the cerebellar cortex, either directly or transcranially, and produce a descending signal in the spinal cord that has different characteristics from the MEP. The cerebellar evoked potential (CEP), located in the dorsolateral and the ventral cord, has an earlier latency and a faster conduction velocity than the MEP. It is predominantly ipsilateral with some contralateral components and also produces EMG responses. In the peripheral nerves, the CEP often produces a pattern of several waves that is different from the one or two predominant contralateral waves of the MEP. The CEP is not diminished by pyramidotomy. It arises from two sites on the cerebellar cortex, medial and lateral. The pathways activated may be the vestibulospinal, rubrospinal, reticulospinal, and fastigiospinal systems. This test seems to offer a monitor of selected motor pathways in the spinal cord largely separate from and complementary to the MEP. The ventral pathways activated probably include those demonstrated to be most essential to basic ambulation after spinal cord injury in primates. Also of importance, one type of evoked potential can facilitate another, which provides additional diagnostic tests. The CEP should be of investigative and clinical value.

Encouraging surgical results in walking patients with epidural metastases.

The management of epidural metastases is in a state of controversy between combined surgical and radiation treatment and treatment by radiation alone. Review of the literature shows that one group, patients who are ambulatory before treatment, have been studied rarely. We analyzed our last 15 years of experience at the Cleveland Clinic and found 39 patients who were ambulatory preoperatively; 84% of these walked during the short term follow-up and 93% of the 1-year survivors walked. These data suggest that surgery has an important role in the management of ambulatory patients.