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T Z Aziz

Publications and source records attributed to T Z Aziz.

At least 37 records · Page 2Linked to original sources
PubMed2001

Targeting the subthalamic nucleus.

The small size and surrounding neuronal structures and fibre tracts make the STN a difficult stereotactic target. In this article we present the technique used by us to target the STN. Our combined experience from two centres comprises 18 lesions and 27 stimulator implants in the STN. Our criteria for patient selection and the use of MRI, frame-on CT and volumetric image fusion are presented. The role of a movement disorder specialist neurologist in the operating theatre, local field potential recording, impedance monitoring, macrostimulation, post-operative CT/MRI and test stimulation are detailed.

Electric Stimulation Therapy↗
PubMed2000

Motor cortex stimulation for chronic neuropathic pain: a preliminary study of 10 cases.

There is growing evidence to support the use of motor cortex stimulation (MCS) in the management of patients with chronic neuropathic pain. A prospective audit of ten patients using a modified staged technique for motor cortex implantation provides further evidence for the analgesic effectiveness of this technique. Ten patients suffering from phantom limb pain (n=3), post stroke pain (n=5), post traumatic neuralgia secondary to gunshot injury to the brain stem (n=1) and brachyalgia secondary to neuro-fibromatosis (n=150% pain relief) and long-term benefit in 4/5 of patients who initially responded to intermittent cortical stimulation (longest follow up 31 months after implantation). Of those patients who benefited two had post stroke pain, two phantom limb pain and one post-traumatic neuralgia. We conclude that motor cortex stimulation is an effective analgesic intervention in some patients with chronic neuropathic pain, but it is difficult if not impossible to predict those patients who may respond to treatment prior to implantation. Randomised controlled trials are now urgently needed to test the effectiveness of motor cortex stimulation under double-blind conditions.

Adult↗
PubMed2000

Frequency analysis of involuntary movements during wrist tracking: a way to identify ms patients with tremor who benefit from thalamotomy.

To identify those multiple sclerosis (MS) patients with disabling tremor who will benefit most from thalamotomy, measurements of frequency spectra of involuntary movements during visually guided wrist tracking were carried out in 11 consecutive patients with MS before and after ventrolateral thalamotomy. Thalamotomy was significantly more effective if patients had disruptive action tremor which appeared as a single peak in the frequency spectra. Such patients showed an average reduction of nearly 80% in tremor magnitude after thalamotomy. In comparison, surgery produced an average reduction of only 30% in 3 other patients who had action tremor but showed multiple peaks in the frequency spectra. Frequency analysis of involuntary movements identifies those MS patients with disabling tremor who benefited most from thalamotomy.

Adult↗
PubMed1999

Effects of visual feedback on manual tracking and action tremor in Parkinson's disease.

Visual feedback is one of the key elements in on-line control of smooth manual tracking. To in- vestigate the effects basal ganglia dysfunction have on visual feedback control, we have tested six advanced Parkinson's disease (PD) patients in comparison with normal controls using visually guided wrist tracking tasks. Tracking performance was assessed under three visual conditions: (1) both guiding target and movement cursor were displayed continuously; (2) the target display was turned off for the second half of each trial; or (3) the cursor display, but not the target, was turned off for the second half of each trial. Thus, for the second half of each trial under conditions 2 and 3, no visual feedback of the relationship between the target and the cursor was available. Results showed that although PD patients had significantly larger tracking errors than controls, and errors significantly increased in both PD patients and controls after withdrawing either visual cue, increases in tracking errors in PD were not significantly different from those in controls. Nor were any significant changes found in the frequency (6-8 Hz) or magnitude of the PD patient's action tremor after withdrawing visual feedback. These results suggest that on-line movement control of wrist tracking movements in advanced PD is not especially reliant on visual feedback. In conjunction with our previous study of multiple sclerosis (MS) patients, the present results confirm that the basal ganglia is less involved in visual guidance of smooth manual tracking than the cerebellar circuits.

Aged↗
PubMed1999

The role of the pedunculopontine region in basal-ganglia mechanisms of akinesia.

The akinesia of Parkinsonism is relieved by pallidotomy and subthalamic nucleotomy, but not by thalamotomy. Therefore, this disabling symptom probably depends upon connections other than the pallidalthalamocortical tracts, possibly efferents of the medial pallidum descending to the upper brainstem. We have previously demonstrated akinesia in the normal monkey following radiofrequency lesioning in the region of the pedunculopontine nucleus (PPN), one of the primary targets for descending pallidal outflow. Here, we confirm that selectively destroying neurones in the PPN area, whilst sparing fibres of passage, results in an akinetic state in normal macaques.

Alfaxalone Alfadolone Mixture↗
PubMed1999

Distal versus proximal arm tremor in multiple sclerosis assessed by visually guided tracking tasks.

OBJECTIVES: To compare action tremor (AT) during manual tracking in normal subjects and patients with multiple sclerosis with tremor (MS-tremor group) and without tremor (MS-no tremor group), and to differentiate tremor occurring predominantly around the distal joint from that involving the proximal joints of the arm. METHODS: Subjects performed both a visually guided ramp tracking task using wrist flexion/extension and a whole arm circle tracking task using shoulder movement. Action tremor at the wrist or shoulder was computed as the SD of the tracking velocity. The ratio of wrist:arm tremor was then calculated to differentiate distal from proximal tremor in the tested arm. Frequency spectra of the records were also examined. RESULTS: During wrist tracking, AT in patients with multiple sclerosis contained a major frequency component at 4-5 Hz; the frequency was slightly lower during whole arm tracking. The ratio of wrist:arm tremor was significantly higher in the MS-tremor group. Of 12 tested arms, eight had tremor significantly weighted towards the distal joint, only one towards the proximal joint, and three had a ratio inside the control range. CONCLUSIONS: AT in the arms of patients with multiple sclerosis can be effectively differentiated into proximal or distal using these two different tracking tasks. Despite the variability of the effects of multiple sclerosis, most of the AT was distal rather than proximal in this group of patients. Possibly conduction block along the corticocerebellocortical pathways caused this distal tremor.

Adult↗
PubMed1998

The role of descending basal ganglia connections to the brain stem in parkinsonian akinesia.

Akinesia is the most disabling symptom of Parkinson's disease. The neural mechanisms underlying it probably involve the descending projections of the basal ganglia to the brain stem as it improves after a pallidotomy or subthalamic nucleotomy but not after a thalamotomy. We describe the effects of lesioning the pedunculopontine nucleus in the normal primate in generating an akinetic syndrome. The possible clinical implications of this study are discussed.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1997

Analysis of action tremor and impaired control of movement velocity in multiple sclerosis during visually guided wrist-tracking tasks.

We investigated the relationship between action tremor (AT) and impaired control of movement velocity (MV) in visually guided tracking tasks, in normal subjects and in patients with multiple sclerosis (MS) with or without motor deficits. The effects of withdrawing visual feedback of either the target or the cursor were then investigated. Visually cued simple reaction times (SRTs) were also measured. The effects of thalamotomy on motor performance in these tasks were evaluated in seven patients. In the MS patients with tremor, there was no correlation between AT and impairment in control of MV, but the latter was highly correlated with an increased delay in SRT. Withdrawal of visually guiding cues increased the error significantly in MV, but reduced AT by approximately 30% in magnitude. Frequency analysis indicated that the AT had two components: (a) non-visual-dependent, oscillatory movements, mainly at 4 Hz; and (2) visual-dependent, repetitive movements, with significant power at 1-2 Hz. Thalamotomy significantly reduced AT but hardly improved accuracy in MV. These results suggest that visual feedback of a spatial mismatch signal may provoke a visually dependent repetitive movement contributing to AT. Conduction delays along either the cortico-cerebello-cortical or the proprioceptive pathways and impaired working memory caused by MS may be responsible for the movement disorders in these patients.

Adult↗
PubMed1996

Endovascular treatment of intracranial aneurysms: a minimally invasive approach with advantages for elderly patients.

An endovascular approach, embolizing intracranial aneurysms with electrolytically detachable coils, is a new minimally invasive treatment of aneurysms. Reviewing our experience with 13 patients aged 70 years or more, 12 patients were treated successfully. Over an average follow-up period of 8 months, there was only one death which might be attributed to an intracranial aneurysm. This compares favourably with mortality rates approaching 50% for either conservative or traditional surgical management of aneurysms presenting with subarachnoid haemorrhage in this age group. Coil embolization, avoiding craniotomy, may offer particular advantages in managing intracranial aneurysms in the elderly patient.

Aged↗
PubMed1995

Neurosurgery at the Radcliffe Infirmary, Oxford: a history.

Neurosurgery started in Oxford in 1938. In this article, we commence the story of Oxford neurosurgery with Thomas Willis and trace the historical thread through William Osler, Charles Sherrington, John Fulton, and Harvey Cushing to Hugh Cairns. The department in Oxford is renowned for the training of neurosurgeons. The initial stimulus for this was the abundance of neurosurgical and neurological expertise in Oxford during World War II with Cairns, and this tradition continued with Joe Pennybacker and his successors. The large and ever increasing work load ensures trainees a wide exposure to challenging neurosurgical problems. An increasing emphasis placed on research has resulted in the creation of two posts; each consists of half-time clinical neurosurgery and half-time research. Hugh Cairns organized the department along "Cushing lines." This organization still exists, allowing us to treat a large number of patients with relatively few beds and an average length of patient stay less than 6 days. We look to the future with confidence.

England↗
PubMed1993

Malignant osteoblastoma of the skull.

A bone tumour of intermediate grade malignancy in the skull is described. These tumours are extremely rare and share several histological features with the benign osteoblastomas and low grade osteosarcomas. They may be associated with local invasion and pulmonary metastases. Treatment of this tumour in the skull poses several problems in view of its proximity to the cerebral cortex.

Adult↗
PubMed1992

Subthalamic nucleotomy alleviates parkinsonism in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-exposed primate.

Research into the neural mechanisms underlying the symptoms of parkinsonism utilizing the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-exposed primate model have shown that the subthalamic nucleus (STN) occupies a central role. As a logical development of this theory, we have studied the effects of thermocoagulative lesions of the STN in the primate model. Such lesions can cause remarkable symptom reversal in the experimental primate model.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗