Biomedical subjects

M Zaaroor

Publications and source records attributed to M Zaaroor.

At least 37 records · Page 2Linked to original sources

PubMed1993

Real-time monitoring of visual evoked potentials.

Steady-state visual evoked potentials (SSVEP) were recorded in response to flashes from eyepatch-mounted light-emitting diodes during neurological surgery and in the intensive care unit. SSVEP were detected and measured with a microprocessor-based waveform correlator. The system enabled a continuous display, in real time, of SSVEP amplitude and latency. SSVEP amplitude and latency changes were monitored throughout a variety of surgical procedures. Some of these procedures directly affect the central visual pathway, some affect the central nervous system as a whole, while others do not affect central nervous system function. In addition, intensive care unit patients with a variety of intracranial pressures were monitored. The results of this study indicate that SSVEP recorded with this method showed changes in SSVEP within seconds of surgical and/or medical decompression of intracranial pressure and were sensitive to specific changes in the visual pathway. Surgical procedures that directly affected the visual system, or elevation of intracranial pressure, resulted in changes in SSVEP. In contrast, procedures that did not affect the functional integrity of the visual system did not affect the recordings.

Adenoma↗

PubMed1991

Effects of myelin or cell body brainstem lesions on 3-channel Lissajous' trajectories of feline auditory brainstem evoked potentials.

Auditory brainstem evoked potentials (ABEP) were recorded from 16 awake cats to obtain 3-Channel Lissajous' Trajectories (3CLTs) using three orthogonal differential electrode configurations (nasion-midline nuchal ridge, left-right mastoids, vertex-midline under the mandible). Potentials, evoked by monaural 80 dBnHL (re, human threshold) clicks, were studied before, and up to 7 weeks after inducing neuronal lesions localized to the cochlear nucleus (CN) or the superior olivary complex (SOC), or myelin lesions localized to the fibers of the trapezoid body connecting these two structures. Neuronal lesions were induced by injection of kainic acid (KA), while myelin lesions were induced by injection of L-alpha-lysophosphatidylcholine (LPC). With CN neuronal lesions the major changes in 3CLT were in the time domain of 'b', 'c' and 'd' (components P2, P3 and P4 of single-channel ABEP). With SOC neuronal lesions the major changes were in 'c' and 'd' of 3CLT (P3 and P4 of ABEP). With trapezoid body lesions the major change was in 'c' (P3 of ABEP). The results are compatible with the peripheral generation of the first ABEP components (P1a and P1b). The second component (P2) is generated by ipsilateral CN neurones and their outputs. The third component (P3) is generated primarily by ipsilateral SOC neurones and their outputs, with the ipsilateral CN providing input. The The fourth component (P4) is generated bilaterally by the SOC neurones and their outputs, receiving their inputs from ipsilateral CN. The fifth ABEP component (P5) is generated by structures central to the SOCs and their immediate outputs. Neither focal neuronal nor myelin lesions were sufficient to produce obliteration of any component, consistent with a set of generators for each of the ABEP components, consisting of both cell bodies and their output fibers, that is distributed spatially in the brainstem.

Animals↗

PubMed1990

Eighth nerve contributions to cat auditory brainstem responses (ABR).

There is a temporal correspondence between some of the early components of the auditory brainstem potentials in cat and the negative peak of the triphasic nerve action potential recorded from selected points along the VIII cranial nerve. The intracranial portion of the VIII nerve in cat has a conduction velocity of 10 meters/s. The initial peak of the ABR, P1a, is coincident with the negative portion of the triphasic VIII nerve action potential within the cochlea as recorded from the round window. The next peak (P1b) of the ABR occurs 400 microseconds later and is coincident with the negative portion of the triphasic VIII nerve action potential recorded from just within the lateral border of the cochlear nucleus. These results are similar to studies of the human ABR that show waves I and II are correlated with activity of the VIII nerve. It is likely that waves P1a and P1b in cat are homologous to waves I and II in human. In cat, these first two peaks of the ABR can be distinguished in vertex to neck recordings but not in vertex to ipsilateral mastoid derivations.

Animals↗

PubMed1990

Wartime neurosurgical experience in Lebanon, 1982-85. I: Penetrating craniocerebral injuries.

The present report analyzes 116 penetrating wounds of the brain sustained during warfare in Lebanon during 1982-85. Two basic mechanisms of injury were encountered: high-velocity bullets, and shrapnel and stones from explosive devices; and in one case a radio antenna penetrated the head through the orbit. The site of impact was at the convexity in 87% of cases and at the base of the skull in the remaining 13%. Surgery was performed in 83% of the patients: debridement-craniotomy in 73%, burr hole for intracranial pressure monitoring only in 6% and scalp closure only in 4%. The remaining 17% did not require surgery because of transbasal penetration without intracranial mass (10%) or due to moribundity. Indriven bone or foreign body fragments were removed only if readily accessible. The mortality rate was highest among patients with a Glasgow Coma Scale of less than or equal to 4 on arrival, after high-velocity bullet wounds, when the intracranial path was multilobar or transventricular, and when associated lesions were accompanied by shock. A follow-up study of the 49 Israeli survivors for almost 6 years revealed intracerebral-retained bone fragments in 48%, but these did not result in increased immediate or late complications (e.g., infection, epilepsy). These results support our conservative approach. Since all victims of penetrating head injuries were evacuated from Lebanon to Rambam Medical Center, Haifa, our report can serve as an estimation of the incidence of penetrating brain wounds and their burden on a front-line hospital.

Brain↗

PubMed1990

Wartime neurosurgical experience in Lebanon, 1982-85. II: Closed craniocerebral injuries.

This report presents 64 patients who sustained military-related closed craniocerebral injuries during the Lebanon conflict of 1982-85, all of whom underwent CT scanning at the initial assessment. Of these, 59% required surgery for removal of hematomas, depressed fractures and for monitoring intracranial pressure, in addition to intensive care management of elevated intracranial pressure and associated insults. CT scan revealed brain concussion only in 23%, depressed fracture in 9%, brain contusion alone in 17%, extracerebral hematomas in 17%, intracerebral hematomas in 11%, and diffuse axonal injury in 22%. Overall mortality was 19%, and the outcome was good in 69%. Various factors affecting survival are discussed, and our findings are compared with those in the literature concerning closed head injuries among civilians. Attention is drawn to the high proportion of diffuse brain injury due to blasts caused by side mines. Despite continued efforts to hasten evacuation from the field and improve the management of warfare-related head trauma, the outcome is still far from satisfactory.

Blast Injuries↗

PubMed1988

Cystic meningiomas.

Four cases of cystic meningiomas were found among 194 meningiomas diagnosed by computed tomography (CT) and operated on during a 7 year period, an incidence of 2%. The cysts were in all cases peritumoral. The cyst's wall was the brain itself, and the ependymal ventricular wall was part of their medial boundary. They contained xanthochromic fluid with a high protein content. Three meningiomas were parasagittal and one was adjacent to the pteryon and the external part of the sphenoid ridge. The mural nodules were in 2 cases apparent single nodes although in one it was part of multiple distant and regional growths, in another the tumour was built by the aggregation of 2 nodes, the remaining case was an "en plaque" meningioma. All were definitely attached to the dura. Histological pattern was different in every case. Those parasagittal were: one pure meningotheliomatous, one mixed meningotheliomatous with pseudo psammomatous and lipoblastic sections and one highly vascular angioblastic; the pteryonal case was psammomatous and microcystic. CT diagnosis is difficult because glial, metastatic and other tumours may look cystic and resemble cystic meningiomas. Nevertheless in 3 cases the correct diagnosis was suspected preoperatively because the solid portion of the tumour showed intense and homogeneous contrast enhancement with a sharp edge and was located adjacent to the dura. On the other hand in the remaining case, the parasagittal solid tumour was not readily apparent on CT (the "en plaque", case), and the tentative preoperative diagnosis was of an epidermoid tumour.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain Diseases↗

PubMed1988

The incidence of multiple meningiomas--do solitary meningiomas exist?

Since the advent of computed tomography (CT) the recognition of the occurrence of multiple intracranial meningiomas (MIM) in the same individual has been on the increase. In our material the incidence of MIM at first assessment of CT films was 20%, with distant multiplicity prevailing over the regional one. This incidence will probably change in the course of time as MIM develop not only concurrently but also consecutively. On the other hand our surgical macroscopic incidence of regional multiplicity alone was 49%. The discrepancy between the CT and surgical findings prompted us to reevaluate the CT studies of 100 consecutive patients. This reevaluation demonstrated: 1. in two cases, small meningiomas were overlooked at first assessment; 2. nineteen cases of solitary globoid meningiomas seemed to be the consequence of the coalescence of adjacent smaller masses. Thus, the CT incidence of MIM increased to 40%, with regional multiplicity prevailing over the distant one. The authors think that the aforesaid findings question the very existence of solitary meningiomas as a pathological entity. They would be the end product of a coalescence of multiple adjacent smaller growths. Accordingly, a more aggressive surgical approach is suggested to include the resection of a generous fringe of dura mater around the main tumour. As this is not always possible, or too risky, a comprehensive complement to surgery like radiotherapy could be given a reasonable randomized trial.

Dura Mater↗

PubMed1987

Spinal cord compression in Paget's disease of bone with reference to sarcomatous degeneration and calcitonin treatment.

Four cases of spinal cord compression stemming from Paget's disease of bone tissue are reported. Sarcomatous degeneration was proved in one case and in another one malignancy was deduced by computed tomography (CT) scanning. Clinical and radiologic manifestations as well as surgical management are discussed. The value of CT scanning of the spine as an aid in the evaluation of structural changes and the size of the soft tissue mass in sarcomatous degeneration of the lesion is stressed. After calcitonin administration, alleviation of pain and improvement in neurological status have occurred in two treated patients.

Aged↗

PubMed1986

Hyperhidrosis and its surgical treatment.

111 sections of high thoracic sympathectomies in 60 cases suffering from primary palmar hyperhidrosis are reported. Surgical results and postoperative complications are discussed in detail. Complications were few in number and were of a transitory nature. No mortality occurred in our series. Various surgical and nonsurgical procedures of treatment are reviewed. Surgical intervention remains the treatment of choice in essential idiopathic hyperhidrosis.

Adolescent↗

PubMed1986

Recurrence of intracranial meningiomas: the role played by regional multicentricity. Part 2: Clinical and radiological aspects.

Globular single meningiomas are generally regarded as benign tumors that can be completely removed. Nevertheless, after a total macroscopic resection including the insertion zone (Grade 1 operation according to Simpson's classification), the incidence of recurrence ranged from 9% to 14% at the 5-year follow-up review. The authors have shown that single meningiomas represent only the visible predominant growth in the midst of a wide neoplastic field in the dura mater. Regional multiplicity in meningiomas would thus seem to be the rule. With this in mind, the authors propose to divide recurrences after Grade 1 operations into true local and false regional. A local recurrence is defined as a regrowth within the limits of the previous dural flap. Regional recurrence is when new growth develops outside the previous craniotomy site; this should not be considered as a recurrence but as a new primary site. These regional recurrences might explain some unexpected late tumor growth occurring after a Grade 1 operation. Five illustrative cases in which regional recurrence was detected by computerized tomography are presented. The authors also propose to add a supplementary grade to Simpson's surgical grading: Grade 0. This operation would entail a wide resection of the dura around the attachment zone of the meningioma. The authors hope that with a Grade 0 operation the incidence of recurrence might be reduced.

Adult↗

PubMed1985

Delayed onset of traumatic extradural hematoma.

During a 4 1/2-year period, seven patients with delayed onset of an extradural hematoma were seen among 80 consecutively treated cases of extradural hematoma for a frequency of 8.75%. The hematomas were insignificant or not present on initial computerized tomography (CT) scanning. Repeat CT scans within 24 hours of admission showed sizeable hemorrhages. Six hematomas were evacuated, and one was reabsorbed spontaneously. In only one patient did neurological deterioration herald the onset of the extradural hematoma, four patients remained unchanged, and two improved before diagnosis. Intracranial pressure (ICP) was monitored in five patients, four of whom showed intermittent rise in pressure despite preventive treatment. Intracranial hypotension and rapid recovery from peripheral vascular collapse seemed to be contributory factors in the delayed onset of an extradural hematoma. Awareness of this entity, a high degree of vigilance, ICP monitoring, and repeat CT scanning within 24 hours of injury are strongly recommended in these cases, especially after decompression by either surgical or medical means, recovery from shock, or whenever there is evidence of even minimal bleeding under a skull fracture on the initial CT scan.

Adult↗

PubMed1985

Necrotizing fasciitis: early awareness and principles of treatment.

Necrotizing fasciitis is a serious life-threatening disease. A series of 11 patients with this disease is described, with emphasis on clinical diagnosis, initiating factors, associated diseases, etiologic pathogens and treatment. The following conclusions can be drawn from this report: Escherichia coli was the most prominent single pathogen, hyperbaric oxygen did not show any added beneficial effect, and diabetes mellitus did not affect morbidity and mortality. There is no doubt that aggressive and radical surgical excision and repeated debridement, combined with i.v. antibiotics and hyperalimentation, are essential to achieve a favorable outcome in this fulminant disease.

Abdomen↗

PubMed1984

The syndrome of the central L-3-herniated disc with special emphasis on motor involvement.

Literature about the clinical characteristics of herniation of the lumbar intervertebral disc is profuse. Due to their predominant frequency, attention was almost entirely devoted to the L-4 and L-5 prolapses. As clinical accuracy still remains a very important target, specially in departments where myelography is not used for the diagnosis of this entity, the authors thought it of interest to describe the clinical picture of the L-3-herniated disc. Special stress is placed on the motor involvement. Fourteen cases form this series. They were all central soft herniations. Cases of spondylotic narrow spinal canal were excluded. The special features were their predominance in people above 50 years old and the compromise of the hip abductors and internal rotator muscle groups making it impossible for the patient to stand on the affected limb (Trendelenburg sign). An abnormal knee jerk was a frequent accompaniment. Contrary to common knowledge the quadriceps muscle strength was almost unaffected. Sensory disturbances were not useful for location. The L-3 section of the lower lumbar spine is the narrowest explaining the reason why 3/4 of the patients had a more or less complete cauda equina syndrome. It was therefore a very dangerous herniation that crippled quickly, needing usually an emergency operation with all the risks involved in this older age group of patients.

Female↗

PubMed1984

Primary cutaneous extravertebral meningioma. Case report.

A case of cutaneous extravertebral meningioma is presented. It was diagnosed in infancy as a lumbar meningocele. Operation was initially refused but was subsequently demanded for cosmetic reasons. The findings were a very thick corrugated skin and a cutaneous meningioma connected by a fibrous tract to the dura mater. The presence of a fibrous stalk linking the tumor to the dura mater might have been the pathogenetic connection between the meningocele and cutaneous meningioma.

Adolescent↗

PubMedDate not supplied

Severe head injury in children--analyzing the better outcome over a decade and the role of major improvements in intensive care.

We suggest a few possible explanations, including improvement of intensive care, as the main cause, for the improved outcome after severe head injury in children and present the predictors of outcome observed in a contemporary series. From January 1984 to June 1988 we saw 117 children (ages 0-14) with postresuscitation GCS (Glasgow Come Scale) scores of 3-8. The more recent cohort of children seen in 1994-1996 was made up of 152 patients. Apart from standard statistics we used a segmentation method called CHAID (SSPS software). Previously known predictors of outcome are found still to apply in our series. Although in the recent period there was a lower proportion of patients with GCS 3-4 (11% versus 32%), a higher percentage had suffered multiple trauma (56% versus 33%). The rates of craniotomy and of ICP monitoring were similar (66% and 61%). Comparison of the two cohorts for outcome at discharge and through 1 year shows that mortality fell from 33% to 10% and the proportion achieving improvement of neurological status increased from 24% to 56%. CHAID analysis showed that the mortality rates of patients within specific groups declined significantly over the two periods: (1) a significant reduction in mortality was seen in patients with GCS 5-7, especially those with diffuse axonal injury (DAI) (17.3% to 0%); (2) no child admitted in shock survived in the earlier period, whereas 7 with GCS 4-6 survived during the recent period. The best model for mortality prediction includes GCS, and in the GCS 4-7 subgroup, the presence of subdural hematoma. It seems that the trend toward better immediate outcome is continuous, and this is the more striking when the severity of injury is taken into consideration. Our belief is that the modern medical and surgical techniques, although incurring higher costs and necessitating ongoing intensity, are well worth the effort.

Adolescent↗

PubMedDate not supplied

Auditory brain-stem evoked potentials in cat after kainic acid induced neuronal loss. I. Superior olivary complex.

Auditory brain-stem potentials (ABRs) were studied in cats for up to 45 days after kainic acid had been injected unilaterally or bilaterally into the superior olivary complex (SOC) to produce neuronal destruction while sparing fibers of passage and the terminals of axons of extrinsic origin connecting to SOC neurons. The components of the ABR in cat were labeled by their polarity at the vertex (P, for positive) and their order of appearance (the arabic numerals 1, 2, etc.). Component P1 can be further subdivided into 2 subcomponents labeled P1a and P1b. The correspondences we have assumed between the ABR components in cat and man are indicated by providing a Roman numeral designation for the human component in parentheses following the feline notation, e.g., P4 (V). With bilateral SOC destruction, there was a significant and marked attenuation of waves P2 (III), P3 (IV), P4 (V), P5 (VI), and the sustained potential shift (SPS) amounting to as much as 80% of preoperative values. Following unilateral SOC destruction the attenuation of many of these same ABR components, in response to stimulation of either ear, was up to 50%. No component of the ABR was totally abolished even when the SOC was lesioned 100% bilaterally. In unilaterally lesioned cats with extensive neuronal loss (greater than 75%) the latencies of the components beginning at P3 (IV) were delayed to stimulation of the ear ipsilateral to the injection site but not to stimulation of the ear contralateral to the injection. Binaural interaction components of the ABR were affected in proportion to the attenuation of the ABR. These results are compatible with multiple brain regions contributing to the generation of the components of the ABR beginning with P2 (III) and that components P3 (IV), P4 (V), and P5 (VI) and the sustained potential shift depend particularly on the integrity of the neurons of the SOC bilaterally. The neurons of the lateral subdivision (LSO) and the medial nucleus of the trapezoid body (MNTB) of the SOC have a major role in generating waves P3 (IV) and P4 (V).

Animals↗

PubMedDate not supplied

Auditory brain-stem evoked potentials in cat after kainic acid induced neuronal loss. II. Cochlear nucleus.

Auditory brain-stem potentials (ABRs) were studied in cats for up to 6 weeks after kainic acid had been injected unilaterally into the cochlear nucleus (CN) producing extensive neuronal destruction. The ABR components were labeled by the polarity at the vertex (P, for positive) and their order of appearance (the arabic numerals 1, 2, etc.). Component P1 can be further subdivided into 2 subcomponents, P1a and P1b. The assumed correspondence between the ABR components in cat and man is indicated by providing human Roman numeral designations in parentheses following the feline notation, e.g., P2 (III). To stimulation of the ear ipsilateral to the injection, the ABR changes consisted of a loss of components P2 (III) and P3 (IV), and an attenuation and prolongation of latency of components P4 (V) and P5 (VI). The sustained potential shift from which the components arose was not affected. Wave P1a (I) was also slightly but significantly attenuated compatible with changes of excitability of nerve VIII in the cochlea secondary to cochlear nucleus destruction. Unexpectedly, to stimulation of the ear contralateral to the injection side, waves P2 (III), P3 (IV), and P4 (V) were also attenuated and delayed in latency but to a lesser degree than to stimulation of the ear ipsilateral to the injection. Changes in binaural interaction of the ABR following cochlear nucleus lesions were similar to those produced in normal animals by introducing a temporal delay of the input to one ear. The results of the present set of studies using kainic acid to induce neuronal loss in auditory pathway when combined with prior lesion and recording experiments suggest that each of the components of the ABR requires the integrity of an anatomically diffuse system comprising a set of neurons, their axons, and the neurons on which they terminate. Disruption of any portion of the system will alter the amplitude and/or the latency of that component.

Animals↗

PubMedDate not supplied

The effects of digital filtering on feline auditory brain-stem evoked potentials.

The power spectrum of the feline auditory brain-stem evoked potentials (ABEPs) consists of 3 frequency bands, similar to the human wave form, but differing in range. The frequency bands in the feline spectra were separated by notches at 326 Hz and 732 Hz. Click-evoked ABEP from 15 cats were digitally filtered in 3 passbands: (1) below 326 Hz ('slow filter'), (2) between 326 and 732 Hz ('medium filter'); and (3) between 732 and 1790 Hz ('fast filter'). Filtering in each of these bands differentially affected the ABEP components. The vertex positive components are labeled by their order of appearance, i.e., 1, 2, ... 5. Peak 1 is subdivided into 2 subcomponents labeled 1a and 1b. The slow filter was associated with the loss of all components leaving a slow potential shift, i.e., the 'pedestal' peaking at the latency of peak 4. The medium filter was associated with the loss of components 1a, 1b and 2, sparing 3 and 4. The fast filter was associated with the loss of 1b and a diminution of 2. Comparing cat and human ABEP, feline components 2, 3 and 4 behaved precisely the same as the human II, III and V. In contrast to the human I, the feline first component (1a) was not detected with the medium filter. No feline component, following peak 1 in the unfiltered wave form, disappeared with the slow and medium filters, and reemerged with the fast filter (as human IV does).(ABSTRACT TRUNCATED AT 250 WORDS)

Acoustic Stimulation↗