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This work examines somatosensory processing in "giant" neurones of the medial pontomedullary reticular formation (PMRF) in the rat, with particular emphasis on the response to cutaneous thermal stimuli. Thermal test stimuli were employed as these were deemed to be more precisely quantifiable than other forms of cutaneous stimulation. Activity was recorded from 235 PMRF neurones in 94 female Long Evans rats (270 to 320 g) anaesthetised with urethane (1,25g/kg, i.p.). Rectal temperature was closely controlled at 38 ± 0,5°C. Standard stereotactic and extracellular recording techniques were employed. PMRF giant neurones were identified by their stereotactic location, large, stable spike amplitudes of long duration, responses to cutaneous mechanical stimuli and receptive field properties, and spontaneous discharge characteristics. Ramp, step and sine wave cutaneous thermal stimuli (35-48 °C) were applied to the glabrous skin on the hindpaw by means of a computer-controlled Peltier device. The location of the units was confirmed by subsequent histology. One hundred and eleven neurones were located in nucleus reticularis pontis caudalis (NPC), and 124 in nucleus reticularis gigantocellularis (NGC). Mechanical stimulation excited 188 of 235 (80%) PMRF neurones (ON-m cells), and inhibited 40 (17%, OFF-m cells). Seven cells (3%) had mosaic receptive fields of excitation and inhibition (complex responses, CX-m). Twenty-eight percent of neurones were responsive to both weak and intense stimuli (mixed neurones). The remainder (72%) responded only to intense mechanical stimulation of the skin (high threshold neurones). The (excitatory or inhibitory) response of the mixed neurones to intense stimuli was generally greater than to mild stimuli, Receptive fields ranged in size from restricted (hindlimbs only) to very extensive (covering the entire body surface). Neurones with small receptive fields were almost exclusively of the high threshold type, and tended to be located in NGC, while mixed neurones tended to have larger receptive fields, and were located predominantly in NPC. Some portion of the hind limbs were represented in the receptive fields of all but one of the neurones studied, while the tail and/ or trunk were represented in 77%, and the forelimbs and face in 28% of receptive fields. Most of the cells responding to cutaneous mechanical stimulation had bilateral (usually symmetric) receptive fields. Spontaneous (background) activity occurred in the absence of any deliberate sensory stimulation in 72% of PMRF neurones. The frequency of spontaneous discharge rates ranged from O to 47 spikes/ s. The coefficient of variation of the spontaneous discharge rate of a given neurone was generally less than 20% (range O to 85%). Of the 235 identified mechanosensitive PMRF neurones, 203 (86%) also responded to cutaneous thermal stimulation (43-48 °C) of the ipsilateral hind paw. Eighty percent of these responded with increased discharge rates (ON-t cells), and 20% were inhibited (OFF-t cells). The polarities of response of individual PMRF neurones to mechanical and thermal stimuli, and to repeated ipsilateral and contralateral thermal stimuli, did not differ significantly. Following transient thermal stimulation, spontaneous discharge rates largely returned to pre-stimulus levels. The thresholds of response to slow ramp (0,15°C/s) and stepped (2°C/s) thermal stimuli occurred both in the innocuous and noxious temperature ranges (below and above 42°C, respectively). The threshold temperatures showed large variability to repeated identical thermal stimuli. Despite the poor reproducibility of the threshold responses, the distribution of thresholds to thermal ramp stimuli was consistently bimodal, with peaks occurring at 39 and 43°C. The bimodality persisted even when the ipsilateral and contralateral data were pooled. The modes of these threshold distributions conform to the maximum discharge ranges for warm and noxious cutaneous receptors. Thus, it is likely that thermal input to individual PMRF neurones is derived from both types of receptors. The responses of PMRF neurones to repeated thermal stimuli were stable and reproducible with respect to magnitude and time course. The average (static) and maximum (dynamic) responses to thermal stimuli were generally small: for example, the mean of the average responses to ramp stimuli was 5,9 spikes/s ± 11,0 SD, (range -28 to 40 spikes/s), and the mean of the maximum responses was 9,3 spikes/s ± 16,1 SD, (range -46 to 65 spikes/s). The absolute change in firing rate of individual PMRF neurones, and of the population, increased monotonically as a function of the intensity of stepped cutaneous thermal stimuli in the range 40 to 48 °C. However, their resolution, based on their average and maximum responses, was poor. Incorporating the post-stimulus responses into the comparisons between different stimulus intensities marginally increased the resolution of these neurones. Thus, while the majority of PMRF neurones are able to distinguish innocuous from noxious stimuli, few are capable of encoding stimulus intensity within the noxious range (above 43 °C). The majority (70%) of PMRF neurones responded to sustained thermal stimuli with a slow increase or decrease to a new static discharge rate which was maintained with little or no adaptation. Latency to onset of response to stepped thermal stimuli varied from 1 to 50 seconds, and the time to maximal response between 5-60 seconds. Many PMRF neurones also showed marked after-discharge for periods of up to 5 minutes after removal of the stimulus. The thermal receptive fields of over 90% of PMRF neurones were large, incorporating at least both hindlimbs. The extensive receptive field sizes of individual PMRF neurones provides evidence against them having a role in stimulus location. The large number of PMRF neurones showing multimodal convergence, their small magnitude responses, their slow response times, and their large receptive fields strongly suggest that these neurones are not participating in classical sensory discrimination. Rather, they may function as stimulus detectors or alternatively play a role in associative processes.

Law Ka Pui, Karlen. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves 159-170). / Abstracts in English and Chinese. / Declaration --- p.1 / Abstract --- p.ii / Acknowledgement --- p.vii / Abbreviations --- p.viii / List of Figures --- p.x / List of Tables --- p.xiv / Contents --- p.xvi / Chapter Chapter One - --- Introduction / Chapter 1.1 --- The Cervical Spine / Chapter 1.1.1 --- Anatomy of Typical Cervical Vertebrae --- p.1 / Chapter 1.1.1.1 --- The Vertebral Body / Chapter 1.1.1.2 --- The Vertebral (Neural) Arch / Chapter 1.1.1.3 --- The Vertebral Processes / Chapter 1.1.1.4 --- The Foramina / Chapter 1.1.2 --- Anatomy of Atypical Cervical Vertebrae --- p.6 / Chapter 1.1.3 --- The Cervical Region of Spinal Cord --- p.8 / Chapter 1.1.3.1 --- Structure of the Spinal Cord / Chapter 1.1.3.1.1 --- Gray Matter / Chapter 1.1.3.1.2 --- White Matter / Chapter 1.1.4 --- The Crucial Ascending Tracts in the White Column --- p.11 / Chapter 1.1.4.1 --- Tracts in Dorsal (Posterior) Column / Chapter 1.1.4.2 --- Tracts in the Lateral Column / Chapter 1.1.4.2.1 --- Posterior Spinocerebellar Tract / Chapter 1.1.4.2.2 --- Anterior Spinocerebellar Tract / Chapter 1.1.4.2.3 --- Lateral Spinothalamic Tract / Chapter 1.1.4.2.4 --- Postero-lateral Tract of Lissauer / Chapter 1.1.4.2.5 --- Spino-olivary Tract / Chapter 1.1.4.3 --- Tracts in the Ventral (Anterior) Column / Chapter 1.1.5 --- The Main Descending Tracts of White Column --- p.14 / Chapter 1.1.5.1 --- Tracts in the Dorsal Column / Chapter 1.1.5.2 --- Tracts in the Lateral Column / Chapter 1.1.5.2.1 --- Lateral Corticospinal Tract / Chapter 1.1.5.2.2 --- Rubrospinal Tract / Chapter 1.1.5.3 --- Tracts in Ventral Column / Chapter 1.1.5.3.1 --- Anterior Corticospinal Tract / Chapter 1.1.5.3.2 --- Vestibulospinal Tract and Reticulospinal Tract / Chapter 1.2 --- The Cervical Spinal Nerve Roots / Chapter 1.2.1 --- The Dorsal Roots --- p.16 / Chapter 1.2.2 --- The Ventral Roots --- p.18 / Chapter 1.2.3 --- The Relation between the Afferent and Efferent Nerve Roots --- p.19 / Chapter 1.3 --- Cervical Myelopathy / Chapter 1.3.1 --- Cause of Cervical Spondylotic Myelopathy --- p.21 / Chapter 1.3.2 --- Clinical Symptoms of Cervical Myelopathy --- p.23 / Chapter 1.4 --- Hypothesis --- p.25 / Chapter Chapter Two - --- Methodology / Chapter 2.1 --- Inclusive Criteria of the Study --- p.27 / Chapter 2.2 --- Magnetic Resonance Imaging of the Cervical Spine --- p.29 / Chapter 2.2.1 --- The Setup of the MRI / Chapter 2.2.2 --- Subject Preparation / Chapter 2.2.3 --- Identification of the Most Stenotic Region in the Cervical Spine / Chapter 2.2.4 --- Measurement of the Most Stenotic Cervical Spinal Cord and Canal / Chapter 2.2.4.1 --- Dimensions of the Spinal Cord and Canal in Sagittal Plane / Chapter 2.2.4.2 --- Dimensions of the Spinal Cord and Canal in Coronal Plane / Chapter 2.2.4.3 --- Dimensions of the Spinal Cord and Canal in Horizontal Plane / Chapter 2.2.4.4 --- Compression Ratio of the Sagittal and Coronal Dimension / Chapter 2.2.5 --- Somatosensory Evoked Potential (SEP) Evaluation / Chapter 2.2.6 --- Choice of Stimulation / Chapter 2.2.7 --- Reception of Signals / Chapter 2.2.7.1 --- Erb's Point / Chapter 2.2.7.2 --- Sensory Cortex Reception / Chapter 2.2.7.3 --- Subject Preparation / Chapter 2.3 --- Upper Limb Functional Assessment --- p.44 / Chapter 2.3.1 --- JOA Score for Cervical Myelopathy / Chapter 2.3.1.1 --- Upper Extremity Function / Chapter 2.3.1.2 --- Lower Extremity Function / Chapter 2.3.1.3 --- Sensory Disturbance / Chapter 2.3.1.4 --- Urinary Function / Chapter 2.3.2 --- Jebsen Hand Function Test / Chapter 2.3.2.1 --- Sub-test 2 - Card Turning Test / Chapter 2.3.2.2 --- Sub-test 3 - Small Object Pinching Test / Chapter 2.3.2.3 --- Sub-test 4 - Simulated Feeding Test / Chapter 2.3.2.4 --- Sub-test 5 - Stacking Checkers Test / Chapter 2.3.2.5 --- Sub-test 6 - Large Light Object Picking Test / Chapter 2.3.2.6 --- Sub-test 7 - Heavy Large Object Picking Test / Chapter 2.3.3 --- The Purdue Pegboard Test / Chapter 2.3.3.1 --- Sub-test 1 - Dominant Hand / Chapter 2.3.3.2 --- Sub-test 2 - Non-dominant Hand / Chapter 2.3.3.3 --- Sub-test 3 - Both Hands / Chapter 2.3.3.4 --- Sub-test 4 - Assembly / Chapter 2.4 --- Statistical Analysis Method --- p.74 / Chapter Chapter Three - --- Results / Chapter 3.1 --- Subject Distribution --- p.76 / Chapter 3.2 --- Magnetic Resonance Imaging Measurement --- p.82 / Chapter 3.3 --- Somatosensory Evoked Potentials Recording --- p.94 / Chapter 3.4 --- JOA (Cervical) Scoring --- p.96 / Chapter 3.5 --- Jebsen Hand Function Test Measurement --- p.101 / Chapter 3.6 --- Purdue Pegboard Test Measurement --- p.105 / Chapter 3.7 --- Statistical Analysis Findings --- p.107 / Chapter 3.8 --- Summary --- p.132 / Chapter Chapter Four - --- Discussion / Chapter 4.1 --- Magnetic Resonance Imaging Measurement --- p.134 / Chapter 4.1.1 --- Cervical Myelopathy Subjects has Small Spinal Cord and Canal / Chapter 4.2 --- Somatosensory Evoked Potential of the Median Nerve --- p.140 / Chapter 4.2.1 --- The Latencies were Preserved in Most of the Subjects / Chapter 4.3 --- Cervical Cord Compression Affects the Hand Function Significantly --- p.143 / Chapter 4.3.1 --- Fine Finger Dexterity Deficiency is a Significant Clinical Symptoms of Cervical Myelopathy Subjects / Chapter 4.3.2 --- Deficiency in Manual Dexterity is another Significant Clinical Symptoms of Cervical Myelopathy Subjects / Chapter Chapter Five - --- Summary and Conclusion --- p.153 / Chapter Chapter Six - --- Further Studies / Chapter 6.1 --- Modification in the Sample Recruitment --- p.157 / Chapter 6.2 --- Modification in Assessment Tools and Procedures --- p.158 / Bibliography --- p.159

Copies of author's previously published articles inserted. Bibliography: leaves I-LXIV. Assesses the diagnostic and prognostic value of early electroencephalography (EEG) and somatosensory evoked potential studies in cortical and non-cortical ischaemic stroke. Both conventional and topographic/quantitative studies were performed. A parallel study was carried out on healthy volunteers to provide an effective control. Equipment and quantitative EEG (qEEG) variability was also assessed.

Copies of author's previously published articles inserted. / Bibliography: leaves I-LXIV. / xxxviii, 239 [77], Lxiv leaves : ill. (chiefly col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Assesses the diagnostic and prognostic value of early electroencephalography (EEG) and somatosensory evoked potential studies in cortical and non-cortical ischaemic stroke. Both conventional and topographic/quantitative studies were performed. A parallel study was carried out on healthy volunteers to provide an effective control. Equipment and quantitative EEG (qEEG) variability was also assessed. / Thesis (Ph.D.)--University of Adelaide, Dept. of Medicine, 1998?

Thesis (Ph. D.)--University of Adelaide, Dept. of Medicine, 1998? / Copies of author's previously published articles inserted. Includes bibliographical references (leaves I-LXIV).

Based on contemporary theoretical knowledge in this prospective study we outline the relationship between a chosen surgical approach (anterior or posterior approach) as it relates to the localization of spinal cord lesion (anterior or posterior spinal pathways) assessed by the use of evoked potentials (SEP, MEP) and the effect of this approach on the postoperative state of patients with cervical spondylotic myelopathy. Furthermore we evaluate clinical outcome of these patients according to several aspects of their MRI and X-ray findings. The study, from 2006 to 2010, comprised 65 patients with clinical signs of cervical myelopathy. These patients had been indicated for surgery, which subsequently was performed by using either the front (anterior - a) or back (posterior - p) approach. The patients were assessed using Nurick and mJOA scores before surgery, then at 12 months, and finally 24 months after surgery. In addition, they were preoperatively examined with a battery of evoked potentials (EP) - somatosensory evoked potential (SEP) and motor evoked potential (MEP) tests. Based on EP, principal spinal cord disability was determined: A - anterior (maximum changes in MEP), P - posterior - maximum change in SEP). The entire group was, on the basis of EP partitioning and the surgical approach used, divided...

Based on contemporary theoretical knowledge in this prospective study we outline the relationship between a chosen surgical approach (anterior or posterior approach) as it relates to the localization of spinal cord lesion (anterior or posterior spinal pathways) assessed by the use of evoked potentials (SEP, MEP) and the effect of this approach on the postoperative state of patients with cervical spondylotic myelopathy. Furthermore we evaluate clinical outcome of these patients according to several aspects of their MRI and X-ray findings. The study, from 2006 to 2010, comprised 65 patients with clinical signs of cervical myelopathy. These patients had been indicated for surgery, which subsequently was performed by using either the front (anterior - a) or back (posterior - p) approach. The patients were assessed using Nurick and mJOA scores before surgery, then at 12 months, and finally 24 months after surgery. In addition, they were preoperatively examined with a battery of evoked potentials (EP) - somatosensory evoked potential (SEP) and motor evoked potential (MEP) tests. Based on EP, principal spinal cord disability was determined: A - anterior (maximum changes in MEP), P - posterior - maximum change in SEP). The entire group was, on the basis of EP partitioning and the surgical approach used, divided...

<p>Degenerativne bolesti kičme nastaju kao posledica promena na dinamičkim segmentima kičmenog stuba. Klinički ove promene se mogu manifestovati u vidu radikulopatije, mijelopatije i radikulomijelopatije. Najče&scaron;će primenjivana metoda operativnog lečenja kod ovih pacijenata je prednja cervikalna diskektomija sa fuzijom koja omogućava adekvatnu anatomsku i funkcionalnu restituciju degenerativno promenjene cervikalne kičme. Imajući u vidu da su već kompromitovane nervne strukture u riziku od dodatnih o&scaron;tećenja u različitim fazama operativnog zahvata primena intraoperativnog neurofiziolo&scaron;kog monitoringa je dobila svoje mesto i u hirur&scaron;kim tretmanima degenerativnih oboljenja kičme. Svrha primene neuromonitoringa je da obezbedi povratnu informaciju hirurgu o promenama u funkciji nervnih struktura pre nego &scaron;to dođe do ireverzibilnih o&scaron;tećenja. Na ovaj način moguće je prevenirati nastanak novog ili pogor&scaron;anje postojećeg deficita. Takođe intraoperativni nalazi neurofiziolo&scaron;kih parametara mogu da ukažu na težinu postojećeg oboljenja i da budu prediktori ishoda lečenja. Ciljevi ove doktorske disertacije bili su utvrđivanje faza operativnog zahvata u kojima najče&scaron;će dolazi do promena u neurofiziolo&scaron;kim parametrima, kao i postojanje korelacije nalaza intraoperativnog neurofiziolo&scaron;kog monitoringa sa preoperativnim kliničkim nalazom pacijenta kao i rezultatima procene ishoda nakon prednje cervikalne diskektomije se fuzijom. Ova studija je obuhvatila 30 pacijenata kod kojih je indikovano operativno lečenje degenerativnih promena u vratnom segmentu kičmenog stuba prednjom mikrodiskektomijom sa fuzijom. Preoperativno je izvođen klinički pregled pacijenata i kori&scaron;teni su Numerička skala bola i Upitnik za pacijente sa bolom u vratnoj kičmi, koji su takođe popunjavani na otpustu i mesec dana nakon operacije. U toku hirur&scaron;ke procedure upotrebom intraoperativnog neurofiziolo&scaron;kog monitoringa registrovani su somatosenzorni (SSEP) i motorni evocirani potencijali (MEP), kao i spontana elektromiografija. Kod svih SSEP do&scaron;lo je do statistički značajnog povećanja amplitude (p&lt;0,05), dok je kod desnog n. medianusa zabeleženo i statistički značajno skraćenje latence (p&lt;0,05). Značajne promene se beleže između početka i kraja operativnog zahvata, kao i u fazi uklanjanja intervertebralnog diska kada dolazi do dekompresije. U vrednostima pražne struje potrebne za dobijanje MEP nije bilo statistički značajnih promena izuzev kod m. triceps brachii obostrano. Kod pacijenata sa radikulopatijom vrednost pražne struje za dobijanje mi&scaron;ićnog odgovora je statistčki značajno niža u odnosu na pacijente sa mijelopatijom (p&lt;0,05). SSEP koreliraju sa poremećajem senzibiliteta, refleksnim odgovorom i bolom. MEP koreliraju takođe sa refleksnim odgovorom, dok negativna korelacija sa manuelnim mi&scaron;ićnim testom pokazuje da klinički očuvana gruba mi&scaron;ićna snaga ne mora biti pokazatelj pravog stanja motornog sistema. Preoperativne vrednosti NDI su se statistički značajno smanjile mesec dana nakon operacije (p&lt;0,05). U vrednostima bola postoji statistčki značajna razlika između svih merenje (p&lt;0,008), izuzev između bola na otpustu i mesec dana nakon operacije (p&gt;0,008). Latenca desnog n.medianusa pokazuje negativnu, a amplituda pozitivnu korelaciju sa vrednostima bola mesec dana postoperativno (p&lt;0,05). Povećanje amplitude i skraćenje latence SSEP ukazuje na značajan stepen dekompresije. Stabilnost MEP ukazuje na intraoperativnu očuvanost motornih puteva i da nije do&scaron;lo do novog motornog deficita niti produbljivanja postojećeg. SSEP i MEP koreliraju sa kliničkim nalazom, dok su vrednosti bola i NDI statistički značajno manje nakon operacije. Ovi rezultati ukazuju da klinički nalaz pacijenta korelira sa neurofiziolo&scaron;kim nalazom, kao i da introperativne promene neurofiziolo&scaron;kih parametara mogu biti prediktivni faktor ishoda operativnog lečenja.</p> / <p>Degenerative spinal diseases are consequence of spondylotic changes on dynamic segments of spinal column. These changes can result in different clinical appearances such as radiculopathy, myelopathy and radiculomyelopathy. The most common surgical procedure used in treatment of this group of patients is anterior cervical discectomy and fusion (ACDF) which can provide adequate anatomical and functional restitution of degenerative cervical spine. Considering the fact that already compromised neural structure can be additionally damaged in different stages of surgical procedure, use of intraoperative neurophysiological monitoring (IONM) has role in surgical treatment of degenerative spinal diseases. The aim of use of IONM is to provide real time feedback for surgeon regarding changes in function of neural structures before irreversible damage occurs. This is the way to prevent new neurological deficit from occurring or to prevent worsening of preexisting deficit. Results of intraoperative monitoring can additionally emphasize severity of disease and help in outcome assessment. The aim of this doctoral thesis was to determine phases of surgical procedure in which changes in neurophysiological parameters occurs most commonly. Another aim was to determine correlation between findings of intraoperative neurophysiological monitoring and clinical assessment and outcome prediction in patients treated with anterior cervical discectomy with fusion. Thirty patients who met inclusion criteria were enrolled in this study. All of them were treated surgically due to degenerative changes of cervical spine and ACDF were performed in all cases. Patients were thoroughly examined before surgery. Detailed neurological examination were performed together with Numeric pain rating scale (NPRS) and Neck Disability index (NDI) questionnaire. NPRS and NDI were applied on discharge from the hospital and one month after surgery. During surgery we registered somatosensory evoked potentials (SSEP), motor evoked potentials (MEP) and spontaneous elektromiography. In all SSEP there were statistically significant increase in amplitude (p&lt;0.05), while in the case of right n. medianus statistically significant shortening of the latency (p&lt;0.05) was recorded. Significant changes are recorded between beginning and the end of the surgical procedure, as well as in the phase of removing of the intervertebral disc when decompression occurs. In the threshold intensity needed to elicit the MEP there were no statistically significant changes except for m. triceps brachii bilaterally. In patients with radiculopathy, the value of the stimulus intensity needed for obtaining muscular response was statistically significantly lower in comparison with patients with myelopathy (p&lt;0.05). SSEP showed the best correlation with sensory disorder, tendon reflexes and pain. MEPs also correlate with tendon reflexes, while a negative correlation with a manual muscle strength testing results shows that clinically preserved muscle strength does not have to be reliable indicator of the motor system condition. Preoperative NDI values were statistically significantly reduced a month after surgery (p&lt;0.05). In pain values there is a statistically significant difference between all measurements (p&lt;0.008), except between pain on release and a month after surgery (p&gt;0.008). The right n.medianus latency shows a negative, and the amplitude shows positive correlation with pain values one month postoperatively (p&lt;0.05). Increasing amplitude and shortening latency of the SSEP indicates a significant degree of decompression. The stability of the MEP indicates the intraoperative preservation of motor pathways and absence of both new motor deficiency or worsening of the existing one. SSEP and MEP correlate with clinical findings, while pain and NDI values are statistically significantly less after surgery. These results indicate that clinical findings in the patients correlate with the neurophysiological findings. Results also points out that the intraoperative changes in neurophysiological parameters can be a predictive factor for the outcome of surgical treatment.</p>