Delayed-onset central poststroke pain due to degeneration of the spinothalamic tract following thalamic hemorrhage: A case report

Central post-stroke pain: advances in clinical and preclinical research

Central poststroke pain (CPSP) is a medical complication that arises poststroke and significantly impacts the quality of life and social functioning of affected individuals. Despite ongoing research, the exact pathomechanisms of CPSP remain unclear, and practical treatments are still unavailable. Our review aims to systematically analyse current clinical and preclinical studies on CPSP, which is critical for identifying gaps in knowledge and guiding the development of effective therapies. The review will clarify the clinical characteristics, evaluation scales and contemporary therapeutic approaches for CPSP based on clinical investigations. It will particularly emphasise the CPSP model initiated by stroke, shedding light on its underlying mechanisms and evaluating treatments validated in preclinical studies. Furthermore, the review will not only highlight methodological limitations in animal trials but also offer specific recommendations to researchers to improve the quality of future investigations and guide the development of effective therapies. This review is expected to provide valuable insights into the current knowledge regarding CPSP and can serve as a guide for future research and clinical practice. The review will contribute to the scientific understanding of CPSP and help develop effective clinical interventions.

Clinical Features of Acute Ischemic Stroke Patients with Hypoesthesia as an Initial Symptom

This study aimed to evaluate the clinical characteristics of acute ischemic stroke (AIS) patients who experienced hypoesthesia as the initial symptom. We retrospectively analyzed the medical records of 176 hospitalized AIS patients who met our inclusion and exclusion criteria and evaluated their clinical features and MRI findings. Among this cohort, 20 (11%) patients presented with hypoesthesia as the initial symptom. MRI scans of these 20 patients identified lesions in the thalamus or pontine tegmentum in 14 and brain lesions at other sites in 6. The 20 hypoesthesia patients had higher systolic (p = 0.031) and diastolic blood pressure (p = 0.037) on admission, and a higher rate of small-vessel occlusion (p < 0.001) than patients without hypoesthesia. The patients with hypoesthesia had a significantly shorter average hospital stay (p = 0.007) but did not differ significantly from those without hypoesthesia in National Institutes of Health Stroke Scale scores on admission (p = 0.182) or the modified Rankin Scale scores for neurologic disability on discharge (p = 0.319). In the patients with acute onset hypoesthesia, high blood pressure, and neurological deficits were more likely to be due to AIS than other causes. Since most of the lesions in AIS patients with hypoesthesia as the initial symptom were found to be small, we recommend performing MRI scans with such patients to confirm AIS.

A systematic review and meta-analysis of neuropathic pain associated with coronavirus disease 2019

BACKGROUND AND OBJECTIVE

Neuropathic pain is an occasionally reported complication of coronavirus disease 2019 (COVID-19) that has received increased attention in scientific literature. In this systematic review and meta-analysis, we aimed to provide information on the frequency of neuropathic pain associated with COVID-19.

DATABASES AND DATA TREATMENT

We systematically reviewed and analysed literature regarding neuropathic pain associated with COVID-19. Literature searches were conducted in PubMed, EMBASE and Cochrane Library databases. We considered prospective and retrospective studies published up until September 2022 (limitations included English language, full-text publications and studies including at least 10 patients). A random effects meta-analysis was performed and heterogeneity and publication bias were assessed.

RESULTS

We identified 149 studies. We included 17 studies in the systematic review, and six studies reporting the frequency of neuropathic pain in the acute/subacute phase of COVID-19 in the meta-analysis. The estimated frequency of neuropathic pain ranged between 0.4 and 25%. Forest plot analysis showed that the random effect overall frequency was 10% (95% confidence interval: 5%-15%), with a high level of heterogeneity (Chi²  = 104; Tau²  = 0.004; df = 5; I²  = 95%; test for overall effect: Z = 3.584; p < 0.0005). The overall risk of bias was moderate in all studies selected, particularly due to the poor description of neuropathic pain diagnostic criteria.

CONCLUSIONS

The pooled estimated frequency of neuropathic pain associated with COVID-19 should be considered with caution due to the high heterogeneity across studies and the poor description of the neuropathic pain diagnostic criteria applied.

SIGNIFICANCE

Emerging evidence supports the development of neuropathic pain as a complication of COVID-19. However, longitudinal studies enrolling consecutive patients with COVID-19 that detail the diagnostic criteria for neuropathic pain are needed to better assess the frequency of this condition.

Role of Sensory Pathway Injury in Central Post-Stroke Pain: A Narrative Review of Its Pathogenetic Mechanism

Central post-stroke pain (CPSP) is a severe chronic neuropathic pain syndrome that is a direct result of cerebrovascular lesions affecting the central somatosensory system. The pathogenesis of this condition remains unclear owing to its extensive clinical manifestations. Nevertheless, clinical and animal experiments have allowed a comprehensive understanding of the mechanisms underlying CPSP occurrence, based on which different theoretical hypotheses have been proposed. We reviewed and collected the literature and on the mechanisms of CPSP by searching the English literature in PubMed and EMBASE databases for the period 2002-2022. Recent studies have reported that CPSP occurrence is mainly due to post-stroke nerve injury and microglial activation, with an inflammatory response leading to central sensitization and de-inhibition. In addition to the primary injury at the stroke site, peripheral nerves, spinal cord, and brain regions outside the stroke site are involved in the occurrence and development of CPSP. In the present study, we reviewed the mechanism of action of CPSP from both clinical studies and basic research based on its sensory pathway. Through this review, we hope to increase the understanding of the mechanism of CPSP.

Delayed development of aphasia related to degeneration of the arcuate fasciculus in the dominant hemisphere nine years after the onset in a patient with intracerebral hemorrhage: a case report

Background

We report on a patient with an intracerebral hemorrhage (ICH), who showed delayed development of aphasia, which was demonstrated via follow up diffusion tensor tractography (DTT) to be related to neural degeneration of the arcuate fasciculus (AF).

Case presentation

A 51-year-old, right-handed male presented with right hemiparesis, which occurred at the onset of a spontaneous ICH in the left corona radiata and basal ganglia. Brain magnetic resonance images showed a hematoma in the left subcortical area at one month after onset and hemosiderin deposits in the left subcortical area at nine years after onset. At four weeks after onset, he exhibited severe aphasia, and Western Aphasia Battery (WAB) testing revealed an aphasia quotient in the 39.6 percentile (%ile). However, his aphasia improved to nearly a normal state, and at three months after onset, his aphasia quotient was in the 90.5 %ile. At approximately eight years after onset, he began to show aphasia, and his aphasia increased slowly with time resulting in a WAB aphasia quotient in the 12.5 %ile at nine years after onset. The integrity of the left AF over the hematoma was preserved on 1-month post-onset DTT. However, the middle portion of the left AF in the middle of the hemosiderin deposits showed discontinuation on 9-year post-onset DTT. The fractional anisotropy value of the left AF was higher on the 9-year post-onset DTT (0.48) than that on the 1-month post-onset DTT (0.35), whereas the mean diffusivity value was lower on the 9-year post-onset DTT (0.10) than that on the 1-month post-onset DTT (0.32). The fiber number of the left AF was decreased to 175 on the 9-year post-onset DTT from 239 on the 1-month post-onset DTT.

Conclusions

We report on a patient with ICH who showed delayed development of aphasia, which appeared to be related to degeneration of the AF in the dominant hemisphere. Our results suggest that DTT would be useful in ruling out neural degeneration of the AF.

The Usefulness of Diffusion Tensor Tractography in Diagnosing Neuropathic Pain: A Narrative Review

Diffusion tensor tractography (DTT) is derived from diffusion tensor imaging. It has allowed visualization and estimation of neural tract injury, which may be associated with the pathogenesis of neuropathic pain (NP). The aim of the present study was to review DTT studies that demonstrated the relationship between neural injuries and NP and to describe the potential use of DTT in the evaluation of neural injuries that are involved in the pathophysiological process of NP. A PubMed search was conducted for articles published until July 3, 2020, which used DTT to investigate the association between neural injuries and NP. The key search phrase for identifying potentially relevant articles was (diffusion tensor tractography AND pain). The following inclusion criteria were applied for article selection: (1) studies involving patients with NP and (2) studies in which DTT was applied for the evaluation of NP. Review articles were excluded. Altogether, 108 potentially relevant articles were identified. After reading the titles and abstracts and assessment of eligibility based on the full-text articles, 46 publications were finally included in our review. The results of the included studies suggested that DTT may be beneficial in identifying the pathophysiological mechanism of NP of various origins including central pain caused by brain injuries, trigeminal neuralgia, sciatica, and some types of headache. Further studies are needed to validate the efficacy of DTT in investigating the pathophysiology of other types of NP.

Repetitive transcranial magnetic stimulation restores altered functional connectivity of central poststroke pain model monkeys

Central poststroke pain (CPSP) develops after a stroke around the somatosensory pathway. CPSP is hypothesized to be caused by maladaptive reorganization between various brain regions. The treatment for CPSP has not been established; however, repetitive transcranial magnetic stimulation (rTMS) to the primary motor cortex has a clinical effect. To verify the functional reorganization hypothesis for CPSP development and rTMS therapeutic mechanism, we longitudinally pursued the structural and functional changes of the brain by using two male CPSP model monkeys (Macaca fuscata) developed by unilateral hemorrhage in the ventral posterolateral nucleus of the thalamus. Application of rTMS to the ipsilesional primary motor cortex relieved the induced pain of the model monkeys. A tractography analysis revealed a decrease in the structural connectivity in the ipsilesional thalamocortical tract, and rTMS had no effect on the structural connectivity. A region of interest analysis using resting-state functional magnetic resonance imaging revealed inappropriately strengthened functional connectivity between the ipsilesional mediodorsal nucleus of the thalamus and the amygdala, which are regions associated with emotion and memory, suggesting that this may be the cause of CPSP development. Moreover, rTMS normalizes this strengthened connectivity, which may be a possible therapeutic mechanism of rTMS for CPSP.

Diagnosis, Treatment, and Management of Dejerine-Roussy Syndrome: a Comprehensive Review

PURPOSE OF REVIEW

Post-stroke pain represents a complex condition with few standardized diagnostic criteria. As such, the array of symptoms is often difficult to categorize and diagnose. Central post-stroke pain (CPSP), also known as Dejerine-Roussy syndrome, presents as painful paresthesia in any part of the body that is usually coupled with sensory abnormalities.

RECENT FINDINGS

In patients who had experienced a cerebrovascular accident, CPSP typically affects the same areas of the body that are also impacted by the general motor and sensory deficits that result from stroke. Though it is generally debated, CPSP is thought to result from a lesion in any part of the central nervous system. Pain usually presents in the range of 3-6 months after the occurrence of stroke, manifesting contralaterally to the lesion, and most commonly involving the upper extremities. For the most accurate diagnosis of CPSP, a thorough history and clinical examination should be supplemented with imaging. Infarcted areas of the brain can be visualized using either CT or MRI. First-line treatment of CPSP is pharmacologic and consists of a three-drug regimen. Despite this, CPSP is often refractory to medical management producing only modest pain reduction in a limited subset of patients. Adverse effects associated with pharmacologic management of CPSP and frequent recalcitrance to treatment have driven alternative minimally invasive methods of pain control which include transcranial stimulation, deep brain stimulation, and neuromodulation. The aim of this review is to provide a comprehensive update to recent advances in the understanding of the treatment and management of CPSP.

Diffusion Tensor Tractography Studies of Central Post-stroke Pain Due to the Spinothalamic Tract Injury: A Mini-Review

Elucidation of the pathophysiological mechanism of central post-stroke pain (CPSP) is essential to the development of effective therapeutic modalities for CPSP. However, the pathophysiological mechanism of CPSP has not yet been clearly elucidated. The recent development of diffusion tensor tractography (DTT), derived from diffusion tensor imaging (DTI), has allowed visualization and estimation of the spinothalamic tract (STT), which has been considered the most plausible neural tract responsible for the pathogenesis of CPSP. In this mini-review, six DTT studies in which CPSP due to STT injury in stroke patients was demonstrated are reviewed. The information provided in the reviewed studies suggests that DTT is useful in the elucidation of the pathophysiological mechanism associated with CPSP. We believe that the reviewed studies will facilitate neurorehabilitation of stroke patients with CPSP. However, DTT studies of CPSP are still in the beginning stage because the total number (six studies) of the reviewed studies is very low and half were case reports. Therefore, further studies involving large numbers of subjects are warranted.