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Biomedical subjects

J L Stone

Publications and source records attributed to J L Stone.

At least 91 records · Page 5Linked to original sources
PubMed1991

Paul Broca and the first craniotomy based on cerebral localization.

Paul Broca (1824-1880) was a well-known French surgeon-anthropologist-neurologist. Best known for his work on cerebral cortical localization and speech mechanisms, Broca also carefully worked out skull and scalp localization for underlying cortical regions. In 1871, Broca treated a man who had sustained a scalp laceration from a blow to the head without loss of consciousness or skull fracture. The patient exhibited a nonfluent aphasia about 1 month after injury and became progressively obtunded and eventually comatose. Suspecting an intracranial abscess, Broca trephined at the region of the left third frontal convolution and drained an epidural abscess. The patient improved transiently but died a few days later. Autopsy showed a left-sided, predominantly frontal purulent meningoencephalitis. Broca's other neurosurgical contributions included various surgical cases, methods for scalp localization of the cerebral convolutions, extensive studies of skull and brain abnormalities, thermoencephalography, and the stimulation of younger surgical colleagues and neurologists to make practical use of cerebral localization.

Abscess↗
PubMed1990

The lateral position--dependant occipital approach--to pineal and medial occipitoparietal lesions. Technical note.

A recent modification of the occipital transtentorial approach to the pineal region and medial-posterior hemisphere is described. The patient is operated upon in a lateral reclining (park bench) position with the side to undergo occipitoparietal craniotomy, slightly dependant. Following dural opening to the margins of the superior sagittal and lateral sinuses, gentle traction with a brain spatula facilitates the occipital transtentorial and transfalcine approach to the incisural region. Ventricular or spinal fluid drainage is often helpful. The occipital lobe falls away from the midline and falcotentorial regions by gravity. Absence of occipital parasagittal bridging veins is a helpful feature and careful convexity dural opening allows the occipital lobe to move laterally. Microsurgical treatment of pineal, splenial, falcotentorial and medial posterior hemisphere lesions may be greatly facilitated. Our experience with six cases is presented. To date, published results of this operative approach have been excellent with the risk of hemianopsia, parenchymal venous infarction, and air embolus much lessened or eliminated.

Adolescent↗
PubMed1990

Digital imaging techniques in dermatology.

Digital imaging is a versatile technique that has been infrequently used in dermatology to record visual images. We have used this technology for 10 patients to follow cutaneous lesions, including alopecia mucinosa, psoriasis, and dysplastic nevi. The setup included a personal computer, digitizer board, monitor, video camera, and lights. An introduction to electronic (digital) imaging is given and some of the many possible applications in dermatology are discussed.

Humans↗
PubMed1990

Skull trepanation among the early Indians of Canada and the United States.

The authors reviewed anthropological reports of skull trepanation (trephination) among the early Indians of Canada and the United States of America. Published reports of 20 trepanations in 19 skulls are reviewed. All were believed to have been performed ante mortem. Most were from the pre-Columbian era. Eleven were from Canada (8 from British Columbia) and 8 from the United States. The location of skull perforation was parietal in 9 cases and less often frontal (3) or occipital (3). The average skull opening was oval or oblong, with a diameter of 3.0 cm. The method of trepanation was probably gradual scraping in most cases. Skull fractures were not present in any case. About 90% of the trepanations showed evidence of healing, indicating survival. The authors discuss the evidence for skull trepanation in the United States and Canada, and compare these findings to the better studied South and Central American material.

Canada↗
PubMed1990

The effect of etomidate on motor evoked potentials induced by transcranial magnetic stimulation in the monkey.

Etomidate (ET) is a known hypnotic agent in neuroanesthesia. This study was designed to examine the reliability of motor evoked potentials (MEPs) after transcranial magnetic stimulation in monkeys anesthetized intravenously with ET. The ET regimen was as follows: an initial dose (0.5 mg/kg) followed by 13 doses (0.2 mg/kg every 6-12 min; mean, 8.0 +/- 1.3 min). The total dose administered was 3.1 mg/kg. The magnetic coil was placed over the MEP scalp stimulation region. Evoked electromyographic responses were recorded from the contralateral abductor pollicis brevis (APB) and abductor hallucis (AH) muscles of the fore- and hindlimbs, respectively. Reproducible MEP responses were consistently recorded while the animal was under total ET anesthesia. The coil demography was altered and the MEP scalp topography was moderately reduced by ET injections. Significant threshold elevation was noted after a total dose of 1.7 mg/kg for APB responses and 0.5 mg/kg for AH responses (P less than 0.05). Marked prolongation of latency was observed after a dose of 0.5 mg/kg for APB MEPs and 2.5 mg/kg for AH MEPs (P less than 0.05). MEP amplitude responses showed marked variability. Repeated doses of ET produced a mean threshold rise of 14 to 28% for the APB and 19 to 29% for the AH. The mean latency delay was 5 to 11% for the APB and 0.5 to 8% for the AH, while the mean amplitude depression was 24 to 59% for the APB and 15 to 50% for the AH. Apparent seizure activity or abnormalities in behavior and feeding were not noted over a 1-year period.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Effects of incremental ketamine hydrochloride doses on motor evoked potentials (MEPs) following transcranial magnetic stimulation: a primate study.

the cumulative dose effect of ketamine hydrochloride (KH) on transcranial magnetic-induced motor evoked potentials (MEPs) was examined in monkeys. Electromyographic (EMG) responses were recorded from the contralateral abductor pollicis brevis (APB) and abductor hallucis (AH) muscles. MEP brain stimulation threshold, latency, and amplitude values were studied. After obtaining baseline recordings, increments of KH (5 mg/kg every 15-20 min) were given i.v. (50 mg/kg total dose). MEPs were repeatedly recorded following KH injections. No loss of potentials was encountered in any animal. However, KH induced significant MEP latency delay in doses >/=35-40 mg/kg and amplitude depression in doses >/=15-20 mg/kg (p < 0.01). Under various KH doses, the amplitude depression ranged from 13.6 to 45.5% for APB and 57.3 to 82% for AH compared to the control values. The MEP latency prolongation ranged from 3.5 to 18% for APB and 4.2 to 13.1% for AH. The stimulation threshold rise ranged from 6.7 to 14.7% for APB and 7 to 17.9% for AH. Statistical correlation was closest between cumulative KH doses and MEP latency prolongation. We conclude that, in the primate model, reliable MEP recording is feasible under deep KH anesthesia. However, awareness of drug-induced response alterations is essential during interpretation of intraoperative MEP changes. Further investigation is warranted regarding the specific dose effect in humans and safety of magnetic stimulation.

Journal Article↗
PubMed1990

The effect of nitrous oxide on transcranial magnetic-induced electromyographic responses in the monkey.

Transcranial magnetic stimulation (TMS) to produce motor evoked potentials (MEPs) is a newly developed intraoperative modality to monitor functional integrity of the motor pathways. The present study was designed to examine the reliability of magnetic MEP recording under nitrous oxide (N2O) inhalation. Following ketamine injection (10 mg/kg i.m.) and endotracheal intubation, 16 monkeys were exposed to N2O:O2 mixture ratios 1:3, 1:1, and 3:1. Electromyographic (EMG) responses, evoked by pulsed magnetic fields applied extracranially to the scalp zone overlying motor cortex, were recorded from the contralateral fore- and hind limb flexor muscles. The scalp topography zone for contralateral muscle excitation was markedly reduced by 75 vol% N2O. Significant stimulation threshold elevation, latency prolongation, and amplitude depression were noted after inhalation of 75 vol% N2O (p <0.05) compared with </=50 vol% N2O inhalation. The mean range of brain stimulation rise was 1%, 7-8%, and 13-20%, and MEP latency delay was 3%, 3-6%, and 7-11% on exposure to 25%, 50%, and 75 vol% N2O, respectively. The mean amplitude response first increased by 20% and 7% with 25% and 50% N2O, respectively, and then reduced by 60% with 75 vol%. We conclude that, in a primate model, while magnetic MEPs could reliably be recorded under 25-75% N2O, the evoked motor responses were least affected by </=50 vol% inhalation. Knowledge of N2O-induced MEP alteration is essential when interpreting the response change while using this agent.

Journal Article↗
PubMed1990

Transtentorial brain herniation in the monkey: analysis of brain stem auditory and somatosensory evoked potentials.

A monkey model of transtentorial brain herniation (TBH) was created to simulate the clinically encountered situation of a gradually expanding intracranial lesion. TBH was produced by extradural balloon inflation over a 4-hour period and documented by the appearance of the pupils as dilated or fixed at midposition. Intracranial pressure (ICP), brain stem auditory evoked potentials (BAEP), and short-latency somatosensory evoked potentials (SSEP) were recorded before, during, and after TBH. Statistical significance from baseline values to TBH was found for diminution of the BAEP amplitude, rise of the ICP, and diminution of the SSEP amplitude. An ICP rise to twice the baseline value and a 25% decrease in Wave V amplitude was found 1 hour before TBH. Changes in BAEP and SSEP took several minutes after deflation to return to baseline values. Analysis of Wave V of the BAEP was as sensitive as ICP in warning of TBH. Discussion centers upon previous animal studies of brain herniation and ICP elevation, and findings reported in humans deteriorating as a result of intracranial mass lesions. BAEP and SSEP monitoring may be used as noninvasive tests for brain stem compression in the setting of primate TBH, and in the future may be used to guide the effectiveness of therapy.

Animals↗
PubMed1989

Nonsurgical management of increased intracranial pressure.

CPP reflects perfusion problems related to increased ICP or inadequate MAP. CPP is a most helpful and practical management tool. The relationship of CBF and CPP depends on cerebral vascular resistance (flow equals pressure divided by resistance). At present, we do not have a practical method to measure vascular resistance or CBV. A close relationship between an increase in CBV and increase in ICP exists. However, the relationship between CBF and ICP is more complex. Whereas CBV is strongly dependent on vasodilation and venous return, CBF is influenced by CPP, vascular resistance, viscosity changes, and focally or diffusely increased ICP. For instance, in hypotensive shock one finds a low CBF with an elevated CBV (and ICP) from vasodilation related to hypercapnia, anoxia, or acidosis. Nevertheless, about two thirds of patients with increased ICP after head injury have increased CBF (hyperemia) and increased CBV. This frequent hyperemia is one rationale for the wide usage of hyperventilation to treat increased ICP. It must be recognized that a group of patients may have ischemia caused by excessive hyperventilation therapy for increased ICP. The PaCO2 must not be allowed to decrease to 20 mmHg or lower, but in some patients a PaCO2 level of 21 to 25 may be predisposing to ischemia. Strong consideration is thus given to monitoring CBF and cerebral oxygen metabolism (arteriovenous oxygen content difference [AVDO2], CMRO2) in states of coma and increased ICP. In such patients, continuous infusion of mannitol may result in improved CBF, and hyperventilation therapy can be less aggressive.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain Diseases↗
PubMed1989

Intrasellar balloon inflation for treatment of symptomatic empty sella syndrome.

Intrasellar extradural placement of a detachable vascular balloon via a transsphenoidal approach was performed successfully in a patient with primary empty sella syndrome, relieving headache and visual field defect. This technique offers an alternative approach to other methods of treating symptomatic empty sella syndrome that require packing of the sella with fat, muscle, cartilage, or bone.

Adult↗
PubMed1989

Outcome of laminectomy for civilian gunshot injuries of the terminal spinal cord and cauda equina: review of 88 cases.

Case records of 88 patients with low-velocity gunshot injuries of the terminal spinal cord and cauda equina treated by laminectomy at Cook County Hospital between 1969 and 1987 were reviewed. Sixty-one patients were operated upon within 72 hours of injury, 29 of whom (47.5%) experienced neurological improvement or pain relief. Twenty-seven patients were operated upon at a later time for associated injuries, 13 of whom (48.1%) experienced neurological improvement or pain relief. When laminectomy was delayed for more than 2 weeks, either arachnoid adhesions (15%) or occult abscesses (17%) were observed. From this review as well as from the literature, it appears that the timing of laminectomy for gunshot injuries of the thoracolumbar and lumbosacral spine is not essential to neurological recovery. It appears, however, that adequate debridement of these injuries, performed as soon as the patient is stable from any associated injuries, may help to mitigate the late sequelae of arachnoiditis, infection, and pain syndromes in the lower extremities.

Adolescent↗
PubMed1989

Anterior cervical debridement and strut-grafting for osteomyelitis of the cervical spine.

A retrospective review of the surgical experience in treating 18 patients with osteomyelitis of the cervical spine is reported. The patients ranged in age from 20 to 60 years and all complained of neck pain upon admission. Ten patients had a prior history of intravenous drug abuse, three had previously suffered penetrating injuries of the neck, and one had an extraspinal site of osteomyelitis. Bacteria were isolated in 13 cases and tuberculosis in three. Neurological abnormalities were present in over one-half of the patients, consisting of myelopathy (nine cases) or radiculopathy (four cases). Plain cervical spine films and polytomography demonstrated vertebral and end-plate destruction, spinal instability, and increased paravertebral soft-tissue shadow in all cases. Computerized tomography and, more recently, magnetic resonance imaging have proven helpful in detecting bone involvement and the presence of epidural extension associated with cervical osteomyelitis. The risk of vertebral body collapse, kyphosis, and myelopathy in the osteomyelitic cervical spine has standardized the management of this problem in this institution to consist of skeletal traction, needle aspiration or blood culture for organism identification, anterior cervical debridement, autogenous iliac graft fusion, and intravenous administration of antibiotics. Spinal stability and neurological improvement were achieved in all 18 patients.

Adult↗
PubMed1988

Electroencephalography in acute head injury.

The established uses of standard and computerized EEG in acute head injury are outlined. Emphasis is placed on EEG correlation with level of consciousness, rostrocaudal deterioration, brainstem lesions, and prognosis. The utility of the standard EEG in seizures and toxic metabolic states accompanying severe head injury is also discussed.

Brain↗
PubMed1988

Evoked potentials in head injury and states of increased intracranial pressure.

Recent clinical studies have addressed the utility of sensory evoked potentials (auditory, somatosensory, and visual) in head injury. The clinical significance of evoked potentials in head trauma, states of increased intracranial pressure, and post-traumatic syndrome is discussed. Emphasis is placed on up-to-date studies discussing evoked potential correlation with clinical findings, lesion localization, intracranial pressure, brain herniation, and prognosis.

Brain↗
PubMed1988

Use of Halifax interlaminar clamps for posterior C1-C2 arthrodesis.

Eight patients with atlantoaxial instability secondary to trauma or rheumatoid arthritis were treated with posterior C1-C2 arthrodesis using the Halifax interlaminar clamp and autogenous bone graft or methylmethacrylate. Thus far, with an average follow-up of 6 months, satisfactory stability has been achieved with no instrument failure.

Arthritis, Rheumatoid↗