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Biomedical subjects

P R Eldridge

Publications and source records attributed to P R Eldridge.

16 recordsLinked to original sources
PubMed1997

Trigeminal neuralgia: a quantitative sensory perception threshold study in patients who had not undergone previous invasive procedures.

The authors investigated 28 patients with "idiopathic" trigeminal neuralgia who had undergone no previous invasive procedures; together these patients had a total of 50 affected trigeminal divisions. Quantitative sensory perception thresholds were measured before operation. Preoperative measurements in the affected divisions indicated raised thresholds for touch (von Frey filaments) and temperature, but not for pinprick or heat pain, in agreement with the findings of Nurmikko. Only the tactile threshold was also significantly affected in the unaffected divisions on the affected side. The authors discuss their findings in relation to the pathophysiology of trigeminal neuralgia, concluding that the origin of the condition is almost certainly central to the gasserian ganglion.

Adult↗
PubMed1997

Sensory effects of microvascular decompression in trigeminal neuralgia.

Nineteen patients with "idiopathic" trigeminal neuralgia, who had not undergone any previous interventional procedures, possessed a vessel or vessels compressing the preganglionic nerve root that was demonstrated by magnetic resonance tomographic angiography. Pain was relieved immediately in all of these patients after they underwent microvascular decompression without observed nerve damage. Although preoperative measurement of sensory perception thresholds showed elevations in the thresholds for touch (von Frey filaments) and warmth and coolness sensations, these thresholds normalized during the postoperative period. An apparent deficit in the pinprick (sharpness) sensation appeared postoperatively, but the deficit gradually regressed and completely disappeared by 1 year after surgery; this phenomenon may have been a statistical anomaly. The patients' pain disappeared immediately postoperatively and remained absent throughout the follow-up period. The authors conclude that damage to the nerve or nerve root is not essential for the relief of trigeminal neuralgia.

Adult↗
PubMed1995

Association between trigeminal neuralgia and multiple sclerosis: role of magnetic resonance imaging.

Seven consecutive patients with multiple sclerosis and trigeminal neuralgia were investigated with MRI to determine the occurrence of a lesion which would account for the patients' pain. Two patients had bilateral symptoms. In the patients with unilateral trigeminal neuralgia vascular compression of the nerve by an artery at the root entry zone on the symptomatic side was confirmed in three patients and an epidermoid tumour distorting the nerve on the symptomatic side was identified in one patient. A demyelinating plaque was identified in only one patient, affecting the trigeminal nerve at the root entry zone at the pons. In those with bilateral symptoms neurovascular compression was identified on both sides in one patient and on one side only in the remaining patient. Microvascular decompression cured the pain in two patients with neurovascular compression. The variable aetiology of trigeminal neuralgia is stressed even in patients with coexistent neurological conditions such as multiple sclerosis, which can cause trigeminal neuralgia independent of other causes.

Adult↗
PubMed1995

Demonstration of neurovascular compression in trigeminal neuralgia with magnetic resonance imaging. Comparison with surgical findings in 52 consecutive operative cases.

Until recently, the inability to demonstrate neurovascular compression of the trigeminal nerve preoperatively resulted in surgery being offered only in cases of severe trigeminal neuralgia (TGN), frequently after a prolonged trial of medical treatment and following less invasive procedures, despite the fact that posterior fossa microvascular decompression gives long-term pain relief in 80% to 90% of cases. To assess whether vascular compression of the nerve could be demonstrated preoperatively, high definition magnetic resonance tomographic angiography (MRTA) was performed in 50 consecutive patients, five of whom had bilateral TGN, prior to posterior fossa surgery. The imaging results were compared with the operative findings in all patients, including two patients who underwent bilateral exploration. Vascular compression of the trigeminal nerve was identified in 42 of 45 patients with unilateral symptoms and on both sides in four patients with bilateral TGN. In the last patient with bilateral TGN, neurovascular compression was identified on one side, and on the other side the compressing superior cerebellar artery was separated from the nerve by a sponge placed during previous surgery. There was full agreement regarding the presence or absence of neurovascular compression demonstrated by MRTA in 50 of 52 explorations, but MRTA misclassified four vessels compressing the trigeminal nerve as arteries rather than veins. In two cases, there was disagreement between the surgical and MRTA findings. In the first of these cases, surgery revealed distortion of the nerve at the pons by a vein that MRTA had predicted to lie 6 mm remote from this point. In the second patient, venous compression was missed; however, this patient was investigated early in the series and did not have gadolinium-enhanced imaging. In nine cases, MRTA correctly identified neurovascular compression of the trigeminal nerve by two arteries. Moreover, MRTA successfully guided surgical reexploration in one patient in whom a compressing vessel was missed during earlier surgery and also prompted exploration of the posterior fossa in two patients with multiple sclerosis and one patient with Charcot-Marie-Tooth syndrome, in whom neurovascular compression was identified preoperatively. It is concluded that MRTA is an extremely sensitive and specific method for demonstrating vascular compression in TGN. As a result, open surgical procedures can be recommended with confidence, and microvascular decompression is now the treatment of choice for TGN at the authors' unit. They propose MRTA as the definitive investigation in such patients in whom surgery is contemplated.

Aged↗
PubMed1994

Vascular contact with the fifth cranial nerve at the pons in patients with trigeminal neuralgia: detection with 3D FISP imaging.

OBJECTIVE: Vascular contact with the trigeminal nerve at the pons is known to cause trigeminal neuralgia; however, this finding also is present in some asymptomatic subjects. We evaluated the usefulness of high-resolution MR imaging and MR angiography of the posterior fossa to determine the presence or absence of vascular contact with the fifth cranial nerve at the pons in patients with trigeminal neuralgia and in control subjects. SUBJECTS AND METHODS: The trigeminal nerves in 40 symptomatic patients and 114 asymptomatic control subjects were examined for the presence or absence of vascular contact at the pons by using three dimension (3D) fast inflow with steady-state precession (FISP) imaging. Imaging parameters were 35/7/15 degrees (TR/TE/flip angle) with a slab thickness of 55 mm and 64 partitions. Contrast-enhanced imaging was done in 10 of 12 patients with normal findings on an unenhanced scan. Axial, coronal, sagittal, and maximum-intensity-projection images were reviewed by two observers who had no knowledge of the clinical details. The findings on MR images were prospectively compared with the surgical findings in 25 patients. RESULTS: On the unenhanced MR images, vascular contact with the trigeminal nerve at the pons was identified in 70% of 40 nerves in patients with trigeminal neuralgia and in a further 15% following injection of contrast medium. Contact between the nerve and two vessels at the pons was seen in 10% of cases, and deformity of the nerve was present in 30% of cases. In the control group, vascular contact with the nerve was identified in 8% of 114 nerves. Contact between the nerve and two vessels or deformity of the nerve was not identified in any control subject. The difference between the two groups was highly significant regarding the presence or absence of vascular contact with the nerve at the pons (p < 0.001, x2 test), distortion of the nerve (p < .001), and contact between the nerve and two vessels (p < .001). The imaging findings were in agreement with the surgical findings regarding the presence or absence of vascular contact with the nerve in all 25 patients who had surgery. Complete or partial pain relief was achieved following microvascular decompression in all patients who had surgery. CONCLUSION: Despite the fact that vascular contact with the trigeminal nerve at the pons is not specific for trigeminal neuralgia, high-definition unenhanced and enhanced 3D FISP imaging and MR angiography at the posterior fossa are useful in determining the presence or absence of vascular contact with or deformity of, the fifth cranial nerve in patients for whom surgery is planned for treatment of trigeminal neuralgia.

Arteries↗
PubMed1993

In vitro assessment of bacterial adhesion to Hydromer-coated cerebrospinal fluid shunts.

The adherence of five strains of Staphylococcus epidermidis and one strain of S. aureus to both untreated and Hydromer-coated silicone rubber cerebrospinal fluid shunts was studied in vitro using epifluorescent image analysis. All five strains of S. epidermidis showed similar levels of adherence to untreated shunts, whilst S. aureus adhered slightly better. The Hydromer coating, a hydrogel material which creates a hydrophilic layer on the shunt surface, was found to reduce bacterial adhesion levels by approximately 90% in the six strains of bacteria tested. Unfortunately, uniform coverage of the shunt surfaces (particularly internally) with Hydromer coating was not achieved during sample preparation. Bacterial adhesion levels in such areas were identical to untreated controls. This may pose problems in the in vivo use of Hydromer-coated shunts.

Bacterial Adhesion↗
PubMed1991

Somatosensory evoked potentials in intracranial hypertension: analysis of the effects of hypoxia.

The loss of somatosensory evoked potentials (SSEP's) was investigated in a feline model of intracranial hypertension. Threshold values of cerebral perfusion pressure (CPP) and cerebral blood flow (CBF) required for maintenance of SSEP's are defined using a mathematical model. The model describes loss of amplitude of SSEP's using the form of a dose-response curve. Amplitude of the SSEP's declined to 50% of control values at a CBF of 15 ml/100 gm/min and a CPP of 20 mm Hg in the normoxic animal; in the presence of mild hypoxia (8 to 9 kPa), a significant increase in these values to 18 ml/100 gm/min and 32 mm Hg, respectively, occurred. No reliable changes in latency or central conduction time were demonstrated. It is concluded that given adequate oxygenation, evoked electrical activity is lost at too low a level of CPP for this parameter to be useful in clinical monitoring. However, even mild hypoxia, when combined with intracranial hypertension, produces a major risk to neuronal integrity.

Animals↗
PubMed1989

Effect of limb tourniquet on cerebral perfusion pressure in a head-injured patient.

Thirty percent of patients with severe head injury also have significant extracranial injuries. Treatment for these injuries should not be allowed to jeopardise the brain which is more susceptible to damage in these circumstances. A case is presented in which significant decrease in cerebral perfusion pressure occurred consequent upon use of a lower limb tourniquet.

Adolescent↗
PubMed1989

Spinal arteriovenous malformations in children.

Three cases of spinal AVM in children are presented, each illustrating a different clinical presentation and anatomical variant. The natural history, treatment, and pathophysiology of these cases is discussed with a survey of the literature.

Angiography↗
PubMed1983

The genetics of the sixth and seventh components of complement in the dog: polymorphism, linkage, locus duplication, and silent alleles.

The complement components C6 and C7 exhibit genetic polymorphism in the domestic dog. In the case of C6, there is a single locus with a null allele and two structural alleles; in the case of C7, there are two linked loci, each with three structural alleles. There is a null allele or locus deletion at one of these loci. In all cases, inheritance is autosomal and codominant. The C7 loci are closely linked to each other and to C6. This complex is not close to the dog major histocompatibility complex (MHC) locus.

Alleles↗