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Biomedical subjects

P R Eldridge

Publications and source records attributed to P R Eldridge.

At least 19 recordsLinked to original sources
PubMed2004

Quantification of tumour response to radiotherapy.

In 1979, the World Health Organization (WHO) established criteria based on tumour volume change for classifying response to therapy as (i) progressive disease (PD), (ii) partial recovery (PR), and (iii) no change (NC). Typically, the tumour volume is reported from diameter measurements, using the calliper method. Alternatively, the Cavalieri method provides unbiased volume estimates of any structure without assumptions about its shape. In this study, we applied the Cavalieri method in combination with point counting to investigate the changes in tumour volume in four patients with high grade glioma, using 3D MRI. In particular, the volume of tumour within the enhancement boundary, the enhancing abnormality (EA), was estimated from T(1) weighted images, and the volume of the non-enhancing abnormality, (NEA) enhancing abnormality, was estimated from T(2) relaxation time and magnetic transfer ratio tissue characterization maps. We compared changes in tumour volume estimated by the Cavalieri method with those obtained using the calliper method. Absolute tumour volume differed significantly between the two methods. Analysis of relative change in tumour volume, based on the WHO criteria, provided a different classification using the calliper and Cavalieri methods. The benefit of the Cavalieri method over the calliper method in the estimation of tumour volume is justified by the following factors. First, Cavalieri volume estimates are mathematically unbiased. Second, the Cavalieri method is highly efficient under an appropriate sampling density (i.e. EA volume estimates can be obtained with a coefficient of error no higher than 5% in 2-3 min). Third, the source of variation of the volume estimates due to disagreements between observers, and within observer, is much greater in the positioning of the calliper diameters than in the identification of the tumour boundaries when applying the Cavalieri method. Additionally, the error prediction formula, available to estimate the coefficient of error of Cavalieri volume estimates from the data, allows us to establish more precise classification criteria against which to identify potentially clinical significant changes in tumour volume.

Brain Neoplasms↗
PubMed2003

Deep brain stimulation of the subthalamic nucleus: effectiveness in advanced Parkinson's disease patients previously reliant on apomorphine.

OBJECTIVES: To assess the efficacy of bilateral subthalamic nucleus (STN) deep brain stimulation (DBS) in patients with advanced Parkinson's disease previously reliant on apomorphine as their main antiparkinsonian medication. METHODS: Seven patients with motor fluctuations despite optimal medical treatment given as predominantly apomorphine infusion (n=6), or intermittent apomorphine injections (n=1) underwent bilateral STN DBS using frameless stereotactic surgery. Standard assessments of parkinsonism and motor fluctuations, using Unified Parkinson's Disease Rating Scale (UPDRS) were performed before and six months after surgery. Assessments were performed both on and off medication, and postoperative with the stimulators switched on and off. RESULTS: Bilateral STN DBS improved motor scores (UPDRS III) by 61% when off medication (p<0.05). Clinical fluctuations (UPDRS IV items 36-39) were reduced by 46.2% (p<0.05). Total daily apomorphine dose was reduced by 68.9% (p<0.05) and apomorphine infusion via a pump was no longer required in four patients. There were no operative complications. Two patients required treatment for hallucinations postoperatively but there was no significant change in mini-mental state examination. CONCLUSIONS: In patients with advanced Parkinson's disease, previously reliant on apomorphine, bilateral STN DBS is an effective treatment to reduce motor fluctuations and enable a reduction in apomorphine use.

Aged↗
PubMed2003

Foramen ovale recordings: a presurgical investigation in epilepsy.

The aim of our study was to determine when foramen ovale recordings add useful information to scalp EEG recordings and magnetic resonance imaging (MRI) with hippocampal measurements. We evaluated the outcome of 79 patients with non-lesional partial epilepsy with presumed temporal seizure onset. Ictal foramen ovale recordings were performed in 16 patients with normal MRI ('MRI-negative group') and 41 patients with lateralizing MRI but non-lateralizing scalp EEG ('discordant group'). 22 patients with concordant MRI and scalp EEG were not investigated with foramen ovale recordings ('concordant group'). The seizure-free rate was higher in concordant than discordant patients despite additional investigation with foramen ovale electrodes (71 and 55% seizure free, respectively). No useful localizing information was added with foramen ovale recordings in MRI-negative patients.

Adult↗
PubMed2003

Microvascular decompression for trigeminal neuralgia in patients with multiple sclerosis.

AIMS: To assess whether microvascular decompression (MVD) is a safe and efficacious treatment for patients with trigeminal neuralgia (TGN) and multiple sclerosis (MS). METHODS: Case records were reviewed of all patients with TGN and MS who underwent posterior fossa exploration with a view to MVD between 1993 and 2001. In all patients, magnetic resonance tomoangiography (MRTA) demonstrated vascular compression. RESULTS: Nine patients were included in the study. Seven patients underwent MVD alone; in 2 patients a partial sensory rhizotomy of the trigeminal nerve was added to the decompression. All patients had excellent initial pain relief. Recurrence of neuralgia was noted in 5 patients after MVD and in 1 of the 2 patients after partial sensory rhizotomy. Long-term pain relief was obtained in 1 patient who underwent a redo MVD after postoperative MRTA scans demonstrated recurrent vascular compression of the root entry zone (REZ). Thus only 4 out of 9 patients maintained pain relief. In addition, 3 patients experienced transient worsening of their MS. CONCLUSIONS: Although MVD provides good initial pain relief, the recurrence rate is much higher than that obtained in 'idiopathic' TGN. Although all procedures for the treatment of TGN are worse than those for idiopathic TGN, it is concluded that because of the high recurrence rate together with the morbidity associated with the procedure MVD should not be offered to patients with TGN and MS.

Adult↗
PubMed2003

Variability in position of the subthalamic nucleus targeted by magnetic resonance imaging and microelectrode recordings as compared to atlas co-ordinates.

BACKGROUND: Traditional methods for localisation of target nuclei for deep brain stimulation (DBS) have used brain atlas co-ordinates for initial targeting. It is now possible to visualise the subthalamic nucleus (STN) on magnetic resonance imaging (MRI) and determine the individual variability of its position. METHODS: The present study was performed in patients undergoing STN DBS for Parkinson's disease. The STN was directly targeted from axially obtained MRI and verified with microelectrode recordings. Postoperatively, the most effective contact was identified for each patient, and its position was calculated. RESULTS: Fifty electrodes were inserted in 25 patients. The target position varied considerably in relation to the mid-commissural point. The mean effective contact position lies just dorsal to the location of the STN in a standard brain atlas. CONCLUSION: The STN varies in position, and can be accurately targeted from MRI alone.

Adult↗
PubMed2003

Use of the NeuroMate stereotactic robot in a frameless mode for movement disorder surgery.

BACKGROUND/AIMS: To evaluate the use of the NeuroMate stereotactic robot with a novel ultrasound registration system for movement disorder surgery (MDS). METHODS: Using the robot in a frameless mode, 51 patients underwent MDS. Surgical planning was carried out using MRI data obtained more than 24 h before surgery. RESULTS: 37 out of 50 targets in the subthalamic nucleus were satisfactorily identified with a single microelectrode trajectory and the final electrode positions were at a mean distance of 1.7 mm from the calculated target. There was a significant improvement in motor scores of the Unified Parkinson's Disease Rating Scale III (off medication) at 6 (43%) and 18 months (51.7%) compared to pre-operative scores (p < 0.05). CONCLUSIONS: The frameless robot using only MRI data can be used for MDS. The temporal separation of imaging from the surgical procedure provides additional time for detailed image analysis and planning.

Humans↗
PubMed2001

Primary intradural classic chondrosarcoma: case report and literature review.

OBJECTIVE AND IMPORTANCE: The exact origin of rare intradural chondrosarcomas remains obscure. We present a case report of an intradural classic chondrosarcoma (a very rare subtype of chondrosarcoma in this location), with a review of the literature, in an attempt to clarify the histogenesis of these tumors. CLINICAL PRESENTATION: A 48-year-old man presented with a 12-month history of progressive right hemiparesis. Computed tomography and magnetic resonance imaging demonstrated a left parietal space-occupying lesion. INTERVENTION: The patient underwent an image-guided, left parietal parasagittal craniotomy. An extrinsic tumor, which seemed to arise from the dura, was macroscopically removed. There was no bone involvement. The histological examination revealed a Grade II classic chondrosarcoma with tumor infiltration into the dura. Adjuvant radiotherapy was administered. CONCLUSION: Intradural chondrosarcomas are rare tumors, the majority of which are mesenchymal. Classic chondrosarcomas in this location are much rarer. Their histogenesis is uncertain. In this case, the origin seems to be from the dura. Because of the malignant potential of these tumors, radical extirpation whenever possible, followed by radiotherapy, is indicated.

Chondrosarcoma↗
PubMed2001

Neurosurgery and facial pain.

This article reviews the diagnosis, differential diagnosis and management of trigeminal neuralgia, the commonest facial pain condition treated by the neurosurgeon. The advantages offered by microvascular decompression as a treatment are reviewed and compared with medical treatment and percutaneous techniques.

Decompression, Surgical↗
PubMed2000

Quantitative magnetic resonance imaging in consecutive patients evaluated for surgical treatment of temporal lobe epilepsy.

We present the results of quantitative Magnetic Resonance Imaging (MRI) in 55 consecutively referred patients with clinical evidence of temporal lobe epilepsy (TLE). The Cavalieri method was used in combination with point counting to provide unbiased estimates of the volume of the left and right hippocampus, amygdala, temporal lobe, lateral ventricles and cerebral hemisphere, and pixel by pixel maps of the T2 relaxation time were computed for both central and anterior sections of the hippocampus. The 99th centiles of hippocampal volume, hippocampal volume asymmetry and T2 relaxation times in 20 control subjects provided limits which identified the presence of MTS. The results of the quantitative MRI were compared with the results of conventional diagnostic MRI, foramen ovale (FO) recording and the WADA test. Thirty-one patients were found to have unilateral MTS (17 left and 14 right) and 7 bilateral MTS. No evidence of MTS was detected in 16 patients. Of the 31 patients diagnosed with unilateral MTS on the basis of hippocampal volume and T2 measurement, 74% and 77% would respectively have received the same diagnosis on the basis of hippocampal volume and T2 measurements alone. In comparison to FO recording, quantitative MRI has a sensitivity of 55% and a specificity of 86%, while conventional diagnostic MRI has a sensitivity of 42% and a specificity of 80% for detection of MTS. Unilateral abnormalities were detected by FO recording in 30% cent of patients who appeared normal on quantitative MRI. WADA test results were available for 40 patients. The findings were consistent with quantitative MRI showing reduced memory function ipsilateral to unilateral MTS in 18 patients, but reduced memory function contralateral to unilateral MTS in two patients, and reduced memory function without MR abnormality in seven patients. WADA testing revealed unilateral memory impairments where MRI found bilateral pathology in 4 patients and in 4 patients in whom quantitative MRI detected unilateral MTS there was no evidence of reduced memory during WADA testing of the corresponding cerebral hemisphere. In the patients with unilateral right MTS a highly significant negative correlation (p = 0.0003) was observed between age of onset and the volume of the contralateral temporal lobe. Quantitative MR imaging of the hippocampus (i.e. volume and T2 measurement) is preferable to conventional radiological reporting for providing objective evidence of the presence of MTS on which to base the referral of patients for surgery, and since it has associated morbidity FO recording is now only being used in selected patients. Furthermore, stereology provides a convenient method for estimating the volume of other brain structures, which is relevant to obtaining a better understanding of the effects of laterality and age of onset of TLE.

Adolescent↗
PubMed2000

Headshaking in horses: possible aetiopathogenesis suggested by the results of diagnostic tests and several treatment regimes used in 20 cases.

Twenty mature horses with typical headshaking of 2 week-7 year duration were studied. Clinical examinations included radiography of the head and nasopharyngeal endoscopy. All were assessed at rest and at exercise, both before and after fitting an occlusive nasal mask, application of tinted contact lenses and the perineural anaesthesia of the infraorbital and posterior ethmoidal branches of the trigeminal nerve. Infraorbital anaesthesia had no effect in 6/7 cases but 11/17 (65%) cases showed a 90-100% improvement following posterior ethmoidal nerve anaesthesia. Tinted contact lenses had no apparent long-term benefit, although 2 cases showed a transient improvement. We found no other evidence to suggest a photic aetiology in the current series of cases. Treatment regimens based on the results of the diagnostic investigative methods included sclerosis of the posterior ethmoidal branch of the trigeminal nerve. This was effective in some cases but the benefits were temporary. Cyproheptadine alone was ineffective but the addition of carbamazepine resulted in 80-100% improvement in 80% of cases. Carbemazepine alone was effective in 88% of cases but results were unpredictable at predefined dose rates. The positive response to carbamazepine, combined with the clinical features is consistent with involvement of the trigeminal nerve, particularly the more proximal branches such as the posterior ethmoidal nerve. Headshaking has some clinical features in common with trigeminal neuralgia in humans. As a result of the findings detailed in this paper, we conclude that a trigeminal neuritis or neuralgia may be the basis of the underlying aetiopathology of equine headshaking. Initial observations of the positive response of headshakers to carbamazepine therapy is encouraging. However, future studies will include a more detailed investigation of dosages, duration of effectiveness (in some cases it appears short-lived) and other effects. In practice there is a realistic possibility of controlling but not curing headshaking with carbamazepine therapy at the present time. Other future investigations will include details of the functional anatomy of the trigeminal nerve and the role of the P2 myelin protein in headshaking and other neurological disease.

Anesthesia↗
PubMed1998

Persistent facial pain following microvascular decompression of the trigeminal nerve.

Pain in the face following microvascular decompression (MVD) can be due to persisting trigeminal neuralgia (TGN) or a variety of other facial pain syndromes. If magnetic resonance tomoangiography (MRTA) indicates continuing vascular compression and the patient has true persistent TGN, then the patient can be relieved of pain by repeating the MVD. When the MRTA is negative for continuing compression alternative techniques may be employed; section of the nerve at the pons may be the treatment of choice for true persistent TGN in the absence of neurovascular compression. In some cases the pain is dysaesthetic in nature and not persistent TGN. This is always associated with previous destructive lesions to the nerve, usually radio-frequency thermocoagulation. When this component to the pain is recognized pre-operatively the patient must be warned not to expect relief of this same component of the pain from MVD. When it is not possible to classify the facial pain clinically, improvement does not occur following MVD even when there is clear evidence of vascular compression on MRTA.

Adult↗
PubMed1997

Case report: inflammatory pseudotumour of the spine, with literature review.

A case of inflammatory pseudotumour of the thoracic spine is reported. There appears to be only one previous report of a spinal case. The patient, a 58-year-old woman, presented with symptoms and signs of spinal cord compression indistinguishable from those due to extradural tumour. The radiological, operative and pathological findings are presented together with a literature review.

Decompression, Surgical↗
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↗