Biomedical subjects

P K Eide

Publications and source records attributed to P K Eide.

At least 19 recordsLinked to original sources

PubMed2006

Intracranial pressure levels and single wave amplitudes, Glasgow Coma Score and Glasgow Outcome Score after subarachnoid haemorrhage.

OBJECT: To relate intracranial pressure (ICP) levels and single ICP wave amplitudes to the acute clinical state (Glasgow Coma Score, GCS) and final clinical outcome (Glasgow Outcome Score, GOS) in patients with subarachnoid haemorrhage (SAH). METHODS: Twenty-seven consecutive patients with severe SAH had their ICP and arterial blood pressure (ABP) continuously monitored during days 1-6 after SAH. The acute clinical state could be assessed in 11 non-sedated cases using the Glasgow Coma Scale, while outcome was assessed in all cases after 6 months using the Glasgow Outcome Scale. The ICP/ABP recordings were stored as raw data files and analyzed retrospectively. For every consecutive 6 seconds time window, mean ICP, mean cerebral perfusion pressure (CPP) and the mean ICP wave amplitude were computed. RESULTS: The GCS during days 1-6 after SAH was significantly related to the mean ICP wave amplitude, but not to the mean ICP or mean CPP. There was also a strong relationship between the mean ICP wave amplitude and GOS 6 months after SAH, with mean ICP wave amplitudes being significantly lower in those with moderate disability/good recovery, as compared with those with severe disability and death. Mean ICP was significantly higher in those who died than in the group with moderate disability/good recovery whereas mean CPP was not different between outcome groups. CONCLUSIONS: In this small patient group the mean ICP wave amplitude during days 1-6 after SAH was related to the acute clinical state (GCS) as well as to the clinical outcome (GOS) 6 months after SAH. Similar relationships were not found for mean ICP or the mean CPP, except for a higher mean ICP in those who died than in those with moderate disability/good recovery.

Aged↗

PubMed2006

Intracranial pulse pressure amplitude levels determined during preoperative assessment of subjects with possible idiopathic normal pressure hydrocephalus.

BACKGROUND: It was previously reported that the intracranial pulse pressure amplitudes were elevated in idiopathic normal pressure hydrocephalus (iNPH) patients responding to shunt surgery. In this study, pulse pressure amplitudes were determined in all patients referred for tentative iNPH, and patients were selected for shunt surgery based on the determination of their threshold levels of intracranial pulse pressure amplitudes. PATIENTS AND METHODS: All patients referred to our department for tentative iNPH during a 12 months time period were included. Using intracranial pressure (ICP) monitoring the intracranial pulse pressure amplitudes were determined as the mean wave amplitude in consecutive 6-seconds time windows. Intracranial pulse pressure amplitudes were defined as being elevated when the mean wave amplitudes were either >or=4 mmHg in >or=70%, >or=5 mmHg in >or=40% or >or=6 mmHg in >or=10% of the ICP recording time. Shunt treatment was offered to those with elevated mean wave amplitudes. Clinical state was assessed by using a NPH Grading Scale and the Stein-Langfitt scale before ICP monitoring, and then repeated after 12 months. RESULTS: Among the 40 iNPH patients included during the 12 months period, the mean wave amplitudes were elevated in 24 patients (60%), while not being elevated in 16 (40%). Neither pre-operative clinical state, radiological ventricular size nor co-morbidity differed between patient groups with elevated or non-elevated mean wave amplitudes. In the shunted patients who had pre-operatively elevated mean wave amplitudes, 91% had very significant clinical change after 12 months (median change in NPH score +4). In those with non-elevated amplitudes and no shunt, clinical state was somewhat worse after 12 months (median change in NPH score -1). CONCLUSIONS: In this one-year material, mean wave amplitudes were elevated in 60% of iNPH patients. In those with elevated mean wave amplitudes who were treated with shunt, 91% had a significant clinical response.

Aged↗

PubMed2006

Comparison of intracranial pressure measured simultaneously within the brain parenchyma and cerebral ventricles.

We report a 48-year-old man treated for acute subarachnoid hemorrhage (SAH) wherein intracranial pressure (ICP) was measured simultaneously within the ventricular cerebrospinal fluid (CSF) and the brain parenchyma (PAR). Single pressure waves within the continuous pressure signal were identified with determination of the single wave parameters pulse amplitude (i.e. pressure difference between diastolic minimum pressure and systolic maximum pressure), mean pressure (i.e. mean pressure from beginning to ending minimum diastolic minimum pressure), and latency (i.e. rise time from diastolic minimum pressure to systolic maximum pressure). A total of 218,589 CSF/PAR single pressure wave pairs were analyzed. For these CSF/PAR wave pairs the mean difference in pulse pressure amplitude was -0.13 mmHg [95% confidence interval (CI) -0.13 to -0.12 mmHg], mean difference in mean single wave pressure -0.71 mmHg (95% CI -0.74 to -0.68 mmHg), and mean difference in latency -0.01 seconds (95% CI -0.01 to -0.01 seconds). Hence, in this patient monitoring ICP within the ventricular CSF or brain parenchyma gave similar results. Moreover, the comparisons of single CSF/PAR wave pulse pressure amplitudes gave no evidence of a pressure gradient from brain parenchyma to the ventricular CSF in this patient.

Cerebral Ventricles↗

PubMed2006

Assessment of quality of continuous intracranial pressure recordings in children.

BACKGROUND: Bad quality of continuous intracranial pressure (ICP) recordings may potentially give wrong diagnostic information. METHOD: This study examined the ICP recordings of 33 children undergoing ICP monitoring during a 12-month period. Their ICP recordings were stored as raw data files and analyzed retrospectively. An automatic algorithm applied to every subsequent 6-second time window of each recording assessed the quality of ICP recordings. Time windows containing 4-18 cardiac beat-induced single ICP waves were accepted; time windows containing artifact-induced pressure waves due to noise in the signal were rejected. For every ICP recording, the number of accepted and rejected time windows were determined. In addition, the raw data ICP signal was assessed by visual inspection to verify the automatic algorithm. Two methods of computing mean pressure of a time window are compared; mean ICP was either computed according to current practice independent of the presence or absence of single ICP waves or computed only for single ICP waves within the time window (mean(SW) ICP). RESULTS: In 4 of the 33 patients (12%), more than 70% of the time windows of their ICP recordings were rejected; in 3 patients 95-100% of time windows were rejected. Visual inspection of the raw ICP signals confirmed the absence of single ICP waves. In these cases, computing mean(SW) ICP, not by mean ICP, revealed the bad signal quality. CONCLUSIONS: This retrospective study showed that in 3 of 33 patients (9%) the quality of the ICP recordings was so bad that they gave wrong diagnostic information. One way of obtaining quality control is to compute mean(SW) ICP, determined only for cardiac beat-induced single ICP waves within a time window.

Adolescent↗

PubMed2005

Intracranial pressure parameters in idiopathic normal pressure hydrocephalus patients treated with ventriculo-peritoneal shunts.

BACKGROUND: Although the mean intracranial pressure (ICP) is normal in patients with idiopathic normal pressure hydrocephalus (iNPH), there could possibly be alterations in their single ICP waves. METHOD: Thirty-nine consecutive patients treated for iNPH with ventriculo-peritoneal shunts were followed prospectively with regard to clinical and radiological findings. Changes in clinical state 12 months after shunt surgery were assessed as change on a 15-3 score NPH Grading Scale, while the changes in ventricular size were assessed by linear measures. The ICP recordings were performed as part of routine pre-operative assessment, stored as raw data files, and analyzed retrospectively. The mean ICP as well as single ICP wave amplitudes were computed and analysed in consecutive 6 second time windows. FINDINGS: Twelve months after shunt surgery, changes in NPH score of 5 or more (very significant improvement) were observed in 12 patients (31%), of 3 to 4 (significant improvement) in 6 patients (15%), of 1 to 2 (slight improvement) in 9 patients (23%) and of -4 to 0 (non-responders) in 12 patients (31%). The ventricular size did not change in any of the outcome categories. While the pre-operative mean ICP was similar between outcome groups, the mean ICP wave amplitude was significantly higher in patients improving clinically as compared to the non-responders. CONCLUSIONS: While pre-operative mean ICP was similar, the mean ICP wave amplitudes were significantly higher in iNPH patients improving clinically after shunt treatment as compared to the non-responders.

Adult↗

PubMed2005

Preoperative spinal hydrodynamics versus clinical change 1 year after shunt treatment in idiopathic normal pressure hydrocephalus patients.

Nineteen consecutive cases treated for idiopathic normal pressure hydrocephalus (iNPH) with ventriculo-peritoneal shunts were clinically followed prospectively. Change in clinical state one year after shunt surgery was assessed as change on a 15-3 score NPH Grade Scale. Preoperative spinal hydrodynamics were assessed using a constant-rate lumbar infusion test. The pressure recordings were stored as raw data files and analysed retrospectively with regard to the mean cerebrospinal fluid pressure (CSFP), as well as mean CSFP wave amplitudes. Changes in NPH score 1 year after shunt surgery correlated significantly with the levels of single CSFP wave amplitudes, but not with the lumbar resistance to CSF outflow (R(out)). Mean CSFP wave amplitude was thus, in this cohort, a better predictor of clinical change one year after shunt treatment than R(out).

Aged↗

PubMed2004

A prospective study on the clinical effect of surgical treatment of normal pressure hydrocephalus: the value of hydrodynamic evaluation.

The effect of surgical treatment of patients with normal pressure hydrocephalus (NPH) is reported to be variable. Candidates for surgery have often been selected using hydrodynamic tests; however, the predictive value of such tests remains uncertain. Seventeen patients with idiopathic NPH underwent continuous computerized intracranial pressure (ICP) monitoring and a steady state lumbar infusion test determining the resistance to cerebrospinal outflow (R(out)). The patients were treated surgically and clinically re-examined approximately 6 months postoperatively using a new NPH score. The effect of surgical treatment was good. The R(out) was positively correlated with the clinical state of the patients before treatment. After surgery, the R(out) correlated well with the improvement in gait and NPH score. Ventricular size was negatively correlated with hydrodynamic variables before treatment. Surgery reduced the ventricular size only slightly and the degree of reduction was linked to the R(out). ICP measurements could not predict outcome in NPH cases.

Adult↗

PubMed2003

The relationship between intracranial pressure and size of cerebral ventricles assessed by computed tomography.

BACKGROUND: This study explored whether assessment of the cerebral ventricular size (or changes in size) by cranial computed tomography (CT) is a reliable way to predict the intracranial pressure (ICP). METHODS: A total of 224 cranial CT scans and continuous 24 hours ICP recordings in 184 patients were examined and compared. In these cases examinations were undertaken on the basis of suspected craniosynostosis, hydrocephalus or extracranial shunt failure. Simultaneous CT scanning and ICP monitoring was performed twice in 31 cases. Various measures of cerebral ventricular size were computed on the basis of CT, including Evan's index, third ventricular index, cella media index and ventricular score. Various measures of ICP were computed by means of the software Sensometrics Pressure Analyser, including computation of mean ICP, numbers of ICP elevations (20-30 mmHg lasting either 0.5, 1, 5 or 10 minutes), and numbers of ICP depressions (-5 or -10 mmHg lasting either 0.5, 1, 5 or 10 minutes) during a standardized recording time of 10 hours. The relationships between the various measures of ventricular size and the various measures of ICP were explored. FINDINGS: There was a weak and non-significant relationship between the various measures of ventricular size and the measures of ICP in the 184 cases. There was a weak relationship between changes in size of cerebral ventricles and changes in ICP in the 31 cases examined twice. INTERPRETATION: The present results suggest that actual size or changes in size of the cerebral ventricles were no reliable predictors of ICP or changes in ICP, suggesting that great caution should be exercised when predicting ICP on the basis of the size of the cerebral ventricles on cranial CT scanning.

Adolescent↗

PubMed2003

A computer-based method for comparisons of continuous intracranial pressure recordings within individual cases.

BACKGROUND: This study assessed two strategies of comparing continuous intracranial pressure (ICP) recordings within individual cases, namely either by calculation of differences in mean ICP or by calculation of differences in numbers of ICP elevations. METHODS: Continuous ICP recordings before and after cranial surgery were both presented as mean ICP and as numbers of ICP elevations of different levels (20 and 25 mmHg lasting either 0.5 or 1 minute). Since the length of pressure recordings differed somewhat between individuals, the numbers of ICP elevations were standardised by computing the numbers of elevations during a 10 hours period. The ICP recordings were analysed by the Sensometrics Pressure Analyser software. The ICP curves included here were selected from a group of 15 children undergoing calvarial expansion surgery for craniosynostosis, in whom continuous ICP monitoring was performed both before and after surgery as part of the diagnostic workout to rule out lasting intracranial hypertension. FINDINGS: After surgery, mean ICP during sleep was reduced by 5 mmHg or more in 5 cases, minimally changed (i.e. 2 mmHg or less) in 6 cases, and variably increased in the other 4 cases. In one of these 4 latter cases, numbers of ICP elevations were increased after surgery, but in all other 14 cases the numbers of ICP elevations were significantly reduced. Reduction of mean ICP by more than 2 mmHg associated with good outcome was observed in 3 of 15 cases (20%), whereas marked and significant reductions in numbers of ICP elevations during sleep combined with good outcome was observed in 12 of 15 cases (80%). INTERPRETATION: Outcome after the 2nd ICP monitoring was more reliably predicted by computing differences in numbers of ICP elevations than by calculation of mean ICP.

Adolescent↗

PubMed2003

Lack of relationship between resistance to cerebrospinal fluid outflow and intracranial pressure in normal pressure hydrocephalus.

OBJECTIVE: To explore whether calculation of resistance to cerebrospinal fluid (CSF) outflow (Rout) by the lumbar constant rate infusion test in a reliable way predicts the intracranial pressure (ICP) profile in normal pressure hydrocephalus (NPH). METHODS: A prospective study was undertaken including 16 cases with clinical signs of normal pressure hydrocephalus that were investigated with both continuous ICP monitoring and the lumbar constant rate infusion test. Intracranial pressure monitoring was performed for about 24 h, and supplied with a simultaneous lumbar constant rate infusion test at the end of the monitoring period. The pressure recordings were analysed using the Sensometrics Pressure Analyser. Various characteristics of the pressure curves were compared. RESULTS: The continuous ICP recordings were considered as normal (mean ICP<11.5 mmHg) in all 16 cases. The lumbar infusion test showed an apparently abnormal resistance to CSF outflow (Rout) (> or =12.0 mmHg/ml/min) in 12 of 16 cases. There was no relationship between lumbar Rout and mean ICP during sleep. We could not find any relationship between lumbar Rout and number of nightly ICP elevations of 1525 mmHg lasting 0.5 or 1 min. Neither resistance to CSF outflow (Rout) nor mean ICP during sleep was related to the ventricular size. CONCLUSIONS: The results of this prospective study revealed no significant relationship between resistance to CSF outflow (Rout) and the ICP profile in NPH cases. The results also suggest that caution should be made when predicting the ICP profile on the basis of measuring the lumbar CSF pressure for a few minutes duration.

Adult↗

PubMed2003

Quantitative analysis of continuous intracranial pressure recordings in symptomatic patients with extracranial shunts.

OBJECTIVES: To explore the outcome of management of possible shunt related symptoms using intracranial pressure (ICP) monitoring, and to identify potential methodological limitations with the current strategies of ICP assessment. METHODS: The distribution of persistent symptoms related to extracranial shunt treatment was compared before and after management of shunt failure in 69 consecutive hydrocephalic cases. Management was heavily based on ICP monitoring (calculation of mean ICP and visual determination of plateau waves). After the end of patient management, all ICP curves were re-evaluated using a quantitative method and software (Sensometrics pressure analyser). The ICP curves were presented as a matrix of numbers of ICP elevations (20 to 35 mm Hg) or depressions (-10 to -5 mm Hg) of different durations (0.5, 1, or 5 minutes). The numbers of ICP elevations/depressions standardised to 10 hours recording time were calculated to allow comparisons of ICP between individuals. RESULTS: After ICP monitoring and management of the putative shunt related symptoms, the symptoms remained unchanged in as many as 58% of the cases, with the highest percentages in those patients with ICP considered normal or too low at the time of ICP monitoring. The quantitative analysis revealed a high frequency of ICP elevations (20 to 35 mm Hg lasting 0.5 to 1 minute) and ICP depressions (-10 to -5 mm Hg lasting 0.5, 1, or 5 minutes), particularly in patients with ICP considered normal. CONCLUSIONS: The value of continuous ICP monitoring with ICP analysis using current criteria appears doubtful in the management of possible shunt related symptoms. This may reflect limitations in the strategies of ICP analysis. Calculation of the exact numbers of ICP elevations and depressions may provide a more accurate description of the ICP profile.

Adolescent↗

PubMed2001

Assessment of intracranial pressure volume relationships in childhood: the lumbar infusion test versus intracranial pressure monitoring.

OBJECT: This study was undertaken to compare the results of two tests that are widely used to assess intracranial pressure-volume relationships in children: the lumbar steady state infusion test providing information about the resistance to cerebrospinal fluid (CSF) outflow (Rout), and continuous intracranial pressure (ICP) monitoring. METHODS: The study included 28 children aged 5-91 months, on whom both tests were performed. The median duration between the tests was 1 month. With the child in general narcosis, the lumbar CSF pressure was recorded before and during infusion of artificial CSF, and the Rout was calculated on the basis of the opening (Po) and plateau (Pp) pressures (Rout=Pp-Po/infusion rate). ICP was recorded every 5 s using a computer-based system. CONCLUSIONS: We found no significant correlation between Rout and mean ICP asleep. There were no significant relationships between abnormal mean ICPs during sleep (defined as either 10 or 15 mmHg) and abnormally high Rout values (defined as either 10 or 12 mmHg/ml/min), and no significant relationships between abnormally high Rout values (10 or 12 mmHg ml(-1) min(-1)) and the presence of abnormal ICP elevations (defined as either 20 or 25 mmHg and lasting 5 min). Therefore the calculation of Rout by the infusion test performed on children under general anesthesia gave no reliable prediction of abnormal ICP.

Cerebrospinal Fluid Pressure↗

PubMed2001

A new method and software for quantitative analysis of continuous intracranial pressure recordings.

OBJECTIVE: A computer software utilising a new method for quantitative analysis of intracranial pressure (ICP), was developed to provide a more accurate analysis of continuously recorded ICP. Intracranial pressure curves were analysed by the software to explore the relationship between mean ICP and the presence of ICP elevations. METHODS: The Sensometrics Pressure Analyser (version 1.2) software provides a quantitative analysis of the ICP curve, presenting the ICP recordings as a matrix of numbers of ICP elevations of different levels (e.g. 20 or 30 or 40 mmHg) and durations (e.g. 0.5, 5 or 10 minutes). The number of ICP elevations may be standardised by calculating the number of elevations during for instance a 10 hour period. The computer software was used to retrospectively analyse the ICP curves in our first consecutive 127 patients undergoing continuous 24 hours ICP monitoring during the two-year period from February 1997 to December 1998. The indications for ICP monitoring were suspected hydrocephalus, craniosynostosis or shunt failure. RESULTS: Analysis of the ICP curves revealed a rather weak relationship between mean ICP and the number of apparently abnormal ICP elevations (that is elevations of 20 mmHg or above). Abnormal ICP elevations were present in a relatively high proportion of cases with a normal mean ICP below 10 mmHg, or a borderline mean ICP between 10 and 15 mmHg. In addition, the ICP data of two cases are presented suggesting that mean ICP may be an inaccurate measure of ICP. CONCLUSIONS: The results of analysing ICP curves by means of this method and software reveal that calculation of ICP elevations of different levels and durations may represent a more accurate description of the ICP curve than calculation of mean ICP. The method may enhance the clinical application of ICP monitoring.

Adolescent↗

PubMed2001

Changes in intracranial pressure after calvarial expansion surgery in children with slit ventricle syndrome.

The effect of calvarial expansion on symptom relief and intracranial pressure (ICP) in three children with slit ventricle syndrome (SVS) and intracranial hypertension despite a functioning ventricular shunt is reported. These children presented with a clinical picture of SVS, accompanied by slit-like ventricles on cranial computer tomography scan and intracranial hypertension. Calvarial expansion was performed by mans of an anterior approach in one case and a posterior approach (modified tiara plastic) in the other two cases. After calvarial expansion, symptoms of intracranial hypertension were abolished in one case and markedly reduced in two cases (observation period 25-36 months). Comparison of ICP before and after surgery was performed by means of new software (Sensometrics Pressure Analyser, version 1.2) that revealed a significant reduction in the number of abnormal ICP elevations after surgery. The results were not accompanied by changes in the size of the cerebral ventricles. This study demonstrates that in children with SVS and intracranial hypertension despite a functioning shunt, calvarial expansion may reduce ICP and produce long-lasting symptom relief. In these cases, we suggest that intracranial hypertension was caused by compromised intracranial volume.

Child↗

PubMed2000

Wind-up and the NMDA receptor complex from a clinical perspective.

More rational treatment of chronic pain depends on increased understanding of the pathophysiological mechanisms underlying the various symptoms and characteristics of chronic pain. Central sensitization of pain represents an important pathophysiological mechanism that has received great attention in recent years. The experimental models used to explore mechanisms of central sensitization include the study of wind-up in animals and temporal summation of pain in humans. Wind-up was described more than 30 years ago as progressively increasing activity in dorsal horn cells following repetitive activation of primary afferent C-fibres. In humans, temporal summation of repeated painful stimuli has been regarded as a psychophysical correlate of wind-up. This review focuses on the relationship between wind-up, temporal summation and central sensitization. In particular, the role of NMDA receptor mechanisms in the modulation of wind-up/temporal summation is discussed. The data presented here indicate that the study of wind-up and temporal summation has given information about some of the complex mechanisms underlying central sensitization. Both wind-up and temporal summation appear to be dependent on NMDA receptor activation. The results of clinical trials in patients with chronic pain suggest that the NMDA receptor may represent a new target for modulation of abnormal temporal summation of pain, as well as other characteristics of chronic pain.

Action Potentials↗

PubMed1998

[Vascular compression and cranial nerve diseases].

This paper offers a review of cranial nerve rhizopathies caused by vascular compression of cranial nerves in the posterior cranial fossa. We present our results of microvascular decompression for trigeminal neuralgia, hemifacial spasm, and glossopharyngeal neuralgia caused by compression of the 5th, 7th and 9th cranial nerves, respectively. After a median observation time of 38 months, 20 of 25 patients with trigeminal neuralgia were completely free of pain, and one patient reported more than 50% pain relief. Four out of five patients treated for hemifacial spasms were completely free of spasms. Of two patients treated for glossopharyngeal neuralgia, one reported complete pain relief, whereas the other reported less than 50% pain relief. No serious complications occurred. The results of microvascular decompression reported in the literature reviewed, including results of the treatment of tinnitus and positional vertigo due to compression of the 8th cranial nerve, hypertension due to compression of the 10th cranial nerve and spastic torticollis due to compression of the 11th cranial nerve. It is concluded that the rationale behind microvascular decompression is supported by an extensive amount of data.

Adult↗

PubMed1998

The effect of peripheral glycerol on trigeminal neuropathic pain examined by quantitative assessment of abnormal pain and sensory perception.

In nine patients with trigeminal neuropathic pain after nerve injury, we examined prospectively the effect of peripheral glycerol neurolysis on abnormal pain and sensory perception. In the painful facial skin area of these patients, we found increased temperature and tactile thresholds and the presence of abnormal temporal summation of pain. In seven patients, neuropathic pain was peripheral and disappeared after application of local anaesthesia at or proximal to the site of nerve injury. Neuropathic pain was central in two patients, and unresponsive to local anaesthesia applied proximal to the site of nerve injury. Six weeks after injection of glycerol proximal to the site of nerve injury, no or marginal pain relief was found in 8 patients with peripheral or central trigeminal neuropathic pain. On the other hand, in one of the patients with peripheral trigeminal neuropathic pain, glycerol was given at the site of nerve injury, and produced total pain relief for the whole observation period of 7 months. In this patient, pain relief was associated with normalisation of abnormal temporal summation of pain, which was not observed in the 8 patients with no or marginal pain relief. No further changes in temperature or tactile thresholds were found in any of the 9 patients after a single injection of absolute glycerol. Total pain relief in one of the patients probably is related to the ability of glycerol to inhibit ongoing ectopic impulse generation at the site of nerve injury. We suggest that glycerol-induced reduction of primary afferent hyperactivity may secondarily result in down-regulation of central neuronal hyperexcitability. The efficacy of application of glycerol at the site of nerve injury in patients with peripheral trigeminal neuropathic pain may warrant further investigation. However, this prospective study does not provide evidence that application of glycerol proximal to the site of nerve injury has a place in the treatment of trigeminal neuropathic pain.

Adult↗

PubMed1998

Pathophysiological mechanisms of central neuropathic pain after spinal cord injury.

After spinal cord injury (SCI), between 10% and 20% of the patients may develop central neuropathic pain. This type of chronic pain usually is a very bothersome sequel and represents a major therapeutic challenge since conventional medical and surgical pain therapies generally are ineffective. This review focuses on recent advances in the understanding of the pathophysiology of this pain syndrome. Important clinical features of central neuropathic pain after SCI include loss of sensations mediated by spinothalamic pathways combined with development of abnormal pain perception (spontaneous continuous pain and abnormally evoked pain). Up-regulation of neuronal activity leading to spontaneous and evoked neuronal hyperactivity/hyperexcitability, may be the neurophysiological substrate for development of abnormal pain perception. This paper describes some neurochemical changes that may be important for the induction and maintenance of neuronal hyperactivity and abnormal pain perception: Increased excitatory glutaminergic activity involving N-methyl-D-aspartate (NMDA) receptor activation, may trigger the intracellular cascade reaction leading to upregulation of neuronal activity/excitability. Changes in voltage-sensitive Na+ channels may contribute to changes in nerve membrane excitability. Other important mechanisms may be loss of endogenous inhibition, including reduced gamma-amino-butyric acid (GABA)ergic, opioid and monoaminergic inhibition. These various mechanisms may provide new targets for treatment of a pain syndrome that traditionally has been so difficult to handle.

Animals↗