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Biomedical subjects

D M Long

Publications and source records attributed to D M Long.

At least 127 records · Page 7Linked to original sources
PubMed1987

Perfluorochemicals as gastrointestinal contrast agents for MR imaging: preliminary studies in rats and humans.

The ability to distinguish bowel from other intraabdominal structures is essential for the accurate diagnosis of intraabdominal disease with MR. Because perfluorochemicals have no protons, they cause no MR signal. Since they are immiscible with water, they create a signal void in bowel independent of bowel contents and thus are suitable as oral contrast agents. Furthermore, they are tasteless and odorless and have no side effects. We evaluated the use of perfluorochemicals by performing MR scans of the abdomen in rats after the oral administration of unemulsified perfluorohexylbromide or perfluoroctylbromide. Since the latter is approved as an investigational drug for oral use in humans, two volunteers were also studied. Both compounds created signal void in the bowel of both rats and human subjects allowing identification of the gastrointestinal tract. The results suggest that these compounds have potential as oral contrast agents for MR imaging.

Animals↗
PubMed1986

Cerebellopontine angle lipoma.

Cerebellopontine angle lipomas are rare lesions that differ from other intracranial lipomas in that they typically present with slowly progressive focal signs and symptoms identical to those of other tumors of this location, and by their propensity for intimate involvement of the adjacent cranial nerves. The lipomas in this study demonstrated this tendency to splay apart and infiltrate the cranial nerves, with the fatty tissue adjacent to the nerves invariably containing portions of the cranial nerves. Hence, the dissection of the adipose tissue from the nerves led to greater than anticipated postoperative neurologic deficits. Therefore, minimal excision of tumor is recommended to achieve decompression. Since preoperative evaluation does not distinguish with certainty this lesion from others more common to this location, intraoperative examination of frozen sections is required to confirm the diagnosis.

Adipose Tissue↗
PubMed1986

The critical role of 3-D CT reconstructions for defining spinal disease.

Three dimensional processing of routine CT images has previously been applied to osseous related maxillo-facial and spinal disorders. Two groups of patients, 25 with substantial spinal trauma and 25 with 'failed back' syndrome had 2-D and 3-D like displays processed by the Cemax 1000 system. The goal was to objectify whether the adjunct of 3-D imaging was truly valuable diagnostically. All images were recorded on 35 mm slides and projected both randomly and as an organized case; intra- and interpersonal evaluations were made. 3-D imaging in 19 of the 25 (76%) trauma patients disclosed additional diagnostic information which was considerably important to both the neuroradiologist and the referring surgeon. In the 'failed back' group, the 3-D images showed supplementary information in 15 of 25 (60%) cases. 3-D displays were usually in color showing complete regional information obtained from high resolution, medium thickness (4 mm) CT slices with minor overlapping (1 mm). The displays were optimized to the plane best defining the pertinent osseous and joint morphology; this included variably rotated and sometimes hemisected views. The images presented here are static, however, when viewed rapidly or by dynamic rotation, the regional morphology results in a highly graphic 3-D presentation.

Humans↗
PubMed1986

Transcutaneous nerve stimulation. Frequency and waveform specificity in humans.

The effects of transcutaneous electrical nerve stimulation (TNS) of a constant alternating current administered at various frequencies and waveforms to volunteer human subjects were investigated. The TNS was found to evoke noncutaneous subjective sensations in all the subjects. Only with a sinusoid waveform of TNS were distinct frequency ranges of the stimulation associated with specific noncutaneous subjective sensations. Our findings suggest that nervous tissue is capable of discriminating the waveform parameters of an electrical stimulus.

Adult↗
PubMed1985

Aging in the nervous system.

This review of the effects of aging on the nervous system covers functional changes, such as slowing of reaction time; behavioral and psychological changes; physiological changes in the brain; and pathological changes. The author discusses the sensory processes in relation to the neurological examination. Dementia due to Alzheimer's disease, normal pressure hydrocephalus, and other causes is also discussed.

Aged↗
PubMed1985

Visual function following optic canal decompression via craniotomy.

Visual function was assessed in 15 eyes of 11 patients who underwent unilateral (seven patients) or bilateral (four patients) optic canal decompression for presumed compressive optic neuropathies. Both immediate and long-term postoperative vision was evaluated in all eyes. Over 90% of the eyes that had undergone nerve decompression had either the same or improved visual acuity and visual field immediately following surgery. In this group of patients there were no deaths and there was only one postoperative complication, a transient dysphasia caused by an epidural hematoma that was evacuated. Long-term follow-up evaluations revealed that most of the eyes retained their immediate postoperative visual function or showed gradual visual improvement with time. The results of this series as well as a review of the available literature indicate that optic canal decompression via craniotomy can be a safe procedure and that it appears to have lasting visual benefit in many patients.

Adolescent↗
PubMed1985

Neurosurgical involvement in tumors of the orbit.

The neurosurgeon has a great deal to offer in the therapy of orbital tumors. Dr. Dandy's supposition that all orbital tumors could be approached by the intracranial route is certainly correct, but technical advances have made the medial and lateral approaches to the orbit more useful for most tumors which are confined to the orbit (22, 25). For those which involve the posterior orbit and canal and have intracranial extensions, the intracranial approach is excellent. Since Dandy's first description of the procedure in 1922, there have been 29 patient reports concerning the results of transcranial canalicular decompression for non-traumatic causes. The most common diagnosis was meningioma (15), and other tumor diagnoses were fibrous dysplasia (7) and hemangioma (2). One-third of the patients were improved; one-third had vision stabilized; and one-third were made worse by surgery. Modern techniques with the microscope and high speed drill have greatly improved these results. Our own experience in the decompression of 15 canals in 11 patients is as follows. There were six patients with meningioma, and two were bilateral. Three patients were found to have a vascular dolichoectasis and one patient had an hemangioma, and in two patients no compression was identified. Immediately postoperatively, two-thirds of the patients were improved, and only one eye (representing 6.7% of the nerves decompressed) was worsened. This resulted from an attempt to totally remove an adherent sheath meningioma. Long-term follow-up median 34 months has demonstrated maintenance of these gains. Eighty percent of the patients have improved or remained stable. These data indicate that the procedure described can be done safely without major risk of visual loss. The neurosurgeon should play an increasingly important role in the evaluation and therapy of posteriorly placed orbital tumors and unexplained compressive optic neuropathy.

Brain Neoplasms↗
PubMed1984

Perfluoroctylbromide as a blood pool contrast agent for liver, spleen, and vascular imaging in computed tomography.

Perfluoroctylbromide (PFOB) in emulsion form was tested as a blood pool imaging agent for computed tomography (CT) in five animals (three dogs and two pigs). Computed tomography of the kidneys, liver, spleen, and mediastinum was performed in the control state and at various time intervals after the end of PFOB infusion. The attenuation coefficient of the vascular space increased by 117 Hounsfield units (HU) (range 105-128 HU), the liver by 54 HU (range 43-70 HU), and the spleen by 77 HU (range 69-86 HU) 30 to 50 min after the end of PFOB infusion, 5 ml/kg. The vascular space enhanced by 25 HU for every g of PFOB/100 ml of blood and remained at almost a constant level for hours after the end of infusion. In conclusion, PFOB emulsion, in addition to hepatosplenic enhancement, produces prolonged and substantial opacification of the vascular space, allowing CT imaging of the heart and vascular structures minutes to hours after the end of infusion.

Angiography↗
PubMed1984

Electrocorticography: information derived from intraoperative recordings during seizure surgery.

The findings of 100 consecutive electrocorticographies in 94 epileptic patients were reviewed. Most of these patients underwent temporal lobectomies. A well defined and circumscript cortical spike focus was found in only 28 tracings whereas multiple sub-foci of spike activity or dissipated areas of spiking were demonstrated in 46 recordings. Cortical spike activity was minimal in 14 and absent in 12 tracings. Additional one-lead depth electrodes (inserted mainly into amygdala and hippocampus) yielded rather little information in contrast to the wealth of information derived from chronic multiple-leads depth implants prior to surgery. The frequent occurrence of dissipated spike foci suggests that, in partial epilepsies (and especially in temporal lobe epilepsy), epileptogenic zones are more widespread than one would expect from the scalp EEG recordings. These findings lend support to the use of en-bloc removal of large portions of an affected lobe.

Adolescent↗
PubMed1983

Stimulation of the peripheral nervous system for pain control.

Transcutaneous stimulation is a proven effective way to relieve pain. Its optimal use requires an accurate patient diagnosis. Treatment of pain as a symptom only is likely to fail. There must be a careful psychosocial evaluation, for the majority of patients who come to the doctor complaining of pain have major psychological, social, or behavioral factors that are most important in the genesis of the complaint. Drug abuse must be corrected. Related symptoms, such as anxiety and depression, must be treated. Then, a thorough trail of transcutaneous stimulation is mandatory. A desultory use will undoubtedly lead to failure. This trial must begin with patient education by experienced personnel. Then the electrodes must be properly applied, and there must be a regular follow-up of stimulation to be certain the patient is utilizing it correctly. The patient must be supported through an adequate trial which should extend over 2-4 weeks before purchase of the device is contemplated. Furthermore, all related nursing and physician personnel must be educated in the proper use of the technique. The uninformed professional who denigrates the therapy is a very effective deterrent to appropriate use. In this situation, transcutaneous electrical stimulation will be of great value in the treatment of acute musculoskeletal injury and acute postoperative pain. It will be effective in the treatment of peripheral nerve injury pain, chronic musculoskeletal abnormalities, chronic pain in the patient who has undergone multiple operations upon the low back and neck, visceral pain, some of the reflex sympathetic dystrophies, and postherpetic neuralgia. Stimulation will not help a complaint which is psychosomatic in origin. It will not influence drug addiction. It is not likely to be useful in any situation where secondary gain is important. The metabolic neuropathies, pain of spinal cord injury, and pain from cerebrovascular accident will not respond frequently enough to warrant more than hopeful trials. The technique is inexpensive, places the patient in control of his own pain, and has no known serious side effects. Its widespread application awaits the development of reasonable systems to provide this service to physicians and patients. Stimulation-induced analgesia deserves a place in the armamentarium of every physician dealing with the complaint of pain.

Back Pain↗
PubMed1983

Perfluorochemicals as liver- and spleen-seeking ultrasound contrast agents.

In this study, Fluosol-DA, 20 per cent (composed of perfluorodecalin and perfluorotripropylamine) was tested as a liver-specific ultrasound contrast agent. Twelve normal rabbits were scanned, utilizing the Picker Microview (10 MHz), prior to and two days following the intravenous administration of 24 ml/kg of Fluosol (or 4.8 g/kg of perfluorochemicals) emulsion to ten of the rabbits and 24 ml/kg of Ringer's solution to two rabbits as control. In all ten rabbits given Fluosol, liver echogenicity increased relative to that of the kidney, whereas the liver remained less echogenic than the kidney in the two rabbits given Ringer's solution. Four independent reviewers correctly identified all rabbits that received Fluosol and both rabbits that received Ringer's solution. It is demonstrated that, similar to PFOB, Fluosol serves as an echogenic contrast material for ultrasound and opacifies the normal rabbit liver.

Animals↗
PubMed1982

Perfluoroctylbromide: a reticuloendothelial-specific and tumor-imaging agent for computed tomography.

Perfluoroctylbromide (PFOB) was evaluated as a liver/spleen-specific and tumor imaging agent in 30 rabbits implanted with VX2 tumors. Computed tomographic (CT) scanning of all rabbits was performed after sacrifice. Half of the animals were given 5 ml/kg of PFOB emulsion intravenously 48 hours prior to sacrifice. Twenty rabbits were used for anatomic correlation and ten for histologic analysis. PFOB concentration was measured in normal liver and spleen in eight rabbits at two days, in six rabbits at seven days, and in six rabbits at 14 days after PFOB administration (5 ml/kg, intravenously). PFOB increased the CT numbers of the liver by 49 HU and the spleen by 250 HU. More important for diagnostic purposes, PFOB produced dense enhancement of the rim of the tumor. The density of the rim of the tumor was increased by 102 HU as a result of accumulation of PFOB in macrophages at the periphery of the tumor. The half-life of PFOB in the liver and the spleen was approximately five days.

Animals↗
PubMed1982

Perfluoroctylbromide: a liver/spleen-specific and tumor-imaging ultrasound contrast material.

The effect of perfluoroctylbromide (PFOB) on liver and tumor echogenicity was evaluated in rabbits. The echogenicity of the kidney, which is not affected by PFOB, was used as the basis for comparison in the liver studies. For the liver echogenicity study, sonography was performed on four rabbits, two with PFOB and two without PFOB, and four rabbits prior to and following the intravenous administration of 5 ml/kg PFOB. All livers were equal to or less echogenic than kidney in the control animals. All livers became more echogenic than kidney two days after administration of PFOB. The effect of PFOB on tumor echogenicity was evaluated in 18 rabbits with VX2 tumor implanted in the liver. Ultrasound studies of all rabbits were performed by the same physician before and two days after half the rabbits had received PFOB (5 ml/kg intravenously). The reviewers correctly identified all rabbits that received PFOB by visualization of an echogenic rim around the hepatic tumors.

Animals↗
PubMed1982

Sleep spindles recorded from deep cerebral structures in man.

The depth and scalp EEG findings in 73 patients with intractable epileptic seizure disorder and in 14 patients with intractable pain were reviewed; stress was laid on the area of earliest spindle activity. It was found that sleep spindles frequently occurred first in frontal depth leads and especially in the superior frontal region (supplementary motor region). In some cases, spindles in frontal depth leads occurred while the patient showed early drowsy activity or even waking activity (with posterior basic rhythm) in the scalp leads. In patients with thalamic implants, spindles tended to appear on the thalamus before appearance on the scalp. The general rule that sleep onset (NREM) is characterized by the appearance of spindles is valid for the scalp EEG only. Deep spindle activity occurs much earlier and probably requires a certain degree of synchronization before spindle activity is noticeable in scalp leads. The superior frontal region is likely to be the starting point of spindle activity.

Adult↗
PubMed1982

A new, treatable source of recurrent meningitis: basioccipital meningocele.

A 19-month-old boy suffered eight episodes of bacterial meningitis. During the ninth episode a meningocele of the basioccipital clivus communicating with the nasopharynx was discovered. Identification of the organism causing the episodes of meningitis was not helpful in pointing to the site of this congenital anatomic defect. Surgical closure of the defect has prevented further recurrences.

Humans↗