Calcineurin-inhibitor induced pain syndrome (CIPS): a severe disabling complication after organ transplantation

Characterization of the calcineurin inhibitor pain syndrome in patients undergoing allogeneic hematopoietic cell transplantation

Calcineurin inhibitor pain syndrome (CIPS) is a rare complication of graft-vs-host disease prophylaxis following allogeneic hematopoietic cell transplant (alloHCT). CIPS presents as severe bilateral lower extremity pain, and the incidence, risk factors, and management of CIPS are poorly characterized.This is a single center retrospective study of patients who received tacrolimus (TAC) following alloHCT to describe the characteristics and management of CIPS and compare to a cohort who did not develop CIPS.Fifteen of 585 alloHCT patients (2.6%) developed CIPS at a median of 5 days following TAC initiation and a median level of 10.5 ng/mL. Severe bilateral foot, ankle, or leg pain were the primary symptoms. Patients with CIPS were younger and more frequently received myeloablative conditioning and total body irradiation compared to patients without CIPS. Analgesic regimens included dihydropyridine calcium channel blockers, gabapentinoids, topical diclofenac, and opioids.Clinicians should be aware of this uncommon but severe adverse effect.

Calcineurin Regulates Synaptic Plasticity and Nociceptive Transmission at the Spinal Cord Level

Calcineurin, the predominant Ca2+/calmodulin-dependent serine/threonine protein phosphatase (also known as protein phosphatase 2B), is highly expressed in immune T cells and the nervous system, including the dorsal root ganglion and spinal cord. It controls synaptic transmission and plasticity by maintaining the appropriate phosphorylation status of many ion channels present at presynaptic and postsynaptic sites. As such, normal calcineurin activity in neurons and synapses is mainly involved in negative feedback regulation in response to increased neuronal activity and intracellular Ca2+ levels. Calcineurin inhibitors (e.g., cyclosporine and tacrolimus) are widely used as immunosuppressants in tissue and organ transplantation recipients and for treating autoimmune diseases but can cause severe pain in some patients. Furthermore, diminished calcineurin activity at the spinal cord level may play a major role in the transition from acute to chronic neuropathic pain after nerve injury. Restoring calcineurin activity at the spinal cord level produces long-lasting pain relief in animal models of neuropathic pain. In this article, we provide an overview of recent studies on the critical roles of calcineurin in regulating glutamate NMDA and AMPA receptors, voltage-gated Ca2+ channels, potassium channels, and transient receptor potential channels expressed in the spinal dorsal horn and primary sensory neurons.

Calcineurin-Inhibitor Induced Pain Syndrome in a Heart Transplant Patient

Calcineurin-inhibitor induced pain syndrome (CIPS) also called the "symmetrical bone syndrome" is a condition describing reversible lower extremity pain in patients after organ transplantation who are receiving calcineurin inhibitors, especially tacrolimus. We present a case of CIPS after orthotopic heart transplant complicated with concurrent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. We emphasize the presentation; diagnostic evaluation, and findings. We then discuss the proposed pathophysiologic mechanisms of CIPS and conclude with discussion of management strategies. Additionally, we present a table to guide clinicians in assessing posttransplant bone pain syndromes. To our knowledge, this is the first article to describe a case of CIPS with concurrent SARS-CoV-2 infection.

Complex regional pain syndrome in a patient with neuroendocrine tumour under treatment with everolimus

Everolimus is an immunosuppressant agent used in organ transplantation and, more recently, in cancer therapy. It has demonstrated beneficial effects in breast cancer, renal cancer, and neuroendocrine tumours. However, the treatment is not without side effects, some of which are still little known. We report the case of a 56 year-old man with a diagnosis of neuroendocrine tumour who developed a complex regional pain syndrome (CRPS) secondary to treatment with everolimus. CRPS has been linked to treatments with everolimus in renal and breast cancer patients as well as in renal transplant patients. To our knowledge, this is the first case of CRPS in a neuroendocrine tumour patient on everolimus treatment.

Prevalence of Musculoskeletal Manifestations in Adult Kidney Transplant's Recipients: A Systematic Review

Background and Objectives: The musculoskeletal (MSK) manifestations in the kidney transplant recipient (KTxR) could lead to decreased quality of life and increased morbidity and mortality. However, the prevalence of these MSK manifestations is still not well-recognized. This review aimed to investigate the prevalence and outcomes of MSK manifestations in KTxR in the last two decades. Materials and Methods: Research was performed in EBSCO, EMBASE, CINAHL, PubMed/MEDLINE, Cochrane, Google Scholar, PsycINFO, Scopus, Science Direct, and Web of Science electronic databases were searched during the years 2000–2020. Results: The PRISMA flow diagram revealed the search procedure and that 502 articles were retrieved from the initial search and a total of 26 articles were included for the final report in this review. Twelve studies reported bone loss, seven studies reported a bone pain syndrome (BPS) or cyclosporine-induced pain syndrome (CIPS), and seven studies reported hyperuricemia (HU) and gout. The prevalence of MSK manifestations in this review reported as follow: BPS/CIPS ranged from 0.82% to 20.7%, while bone loss ranged from 14% to 88%, and the prevalence of gout reported in three studies as 7.6%, 8.0%, and 22.37%, while HU ranged from 38% to 44.2%. Conclusions: The post-transplantation period is associated with profound MSK abnormalities of mineral metabolism and bone loss mainly caused by corticosteroid therapy, which confer an increased fracture risk. Cyclosporine (CyA) and tacrolimus were responsible for CIPS, while HU or gout was attributable to CyA. Late diagnosis or treatment of post-transplant bone disease is associated with lower quality of life among recipients

An Approach to Neurological Disorders in a Kidney Transplant Recipient

Kidney transplantation is the preferred treatment modality in patients with ESKD. However, there are associated complications that arise from immunosuppressive medications, infections, and associated comorbidities. Neurologic disorders frequently develop in patients who have received a kidney transplant, which in turn increases the associated morbidity and mortality. This review discusses the common neurologic disorders after kidney transplantation, including infections, cognitive decline, drug-related conditions, malignancy, seizure, and other neurologic complications.

Chronic pain 1-5 years after heart transplantation-A nationwide cross-sectional cohort study

Aim

To provide a multidimensional assessment of self-reported chronic pain 1-5 years after heart transplantation and its relationship with self-reported well-being, fatigue, recovery, self-efficacy and socio-economic factors and to explore differences between heart recipients and a cohort of lung recipients.

Design

This multicentre, cross-sectional, cohort study is a part of the Swedish national Self-management after thoracic transplantation study.

Methods

Six questionnaires were distributed at the heart recipients yearly follow-up (1-5 years) at three Swedish university hospitals 2014-2017.

Results

The study group comprised of 79 heart recipients, 25 women and 54 men with a mean age of 52.68 years. Chronic pain among heart recipients was common and those not in paid employment as well as those with low psychological well-being and high general fatigue reported significantly more pain. Female heart recipients were more affected by pain. General health and vitality, general fatigue, physical fatigue and reduced activity were related to the pain intensity score.

Relevance to clinical practice

As it is the duty of the healthcare system to provide adequate pain treatment, screening for pain should be a mandatory part of long-term follow-up.

Bone infarction of the hip after hand allotransplantation: A case report

Vascularized composite allotransplantation represents as an emerging field in reconstructive surgery. However, some complications can be associated with the procedure. The authors describe a case of bone infarctions of the bilateral hip joints following the first hand allotransplantation in Taiwan. A 45-year-old man who experienced a traumatic amputation of the distal third of his forearm received a hand transplantation from a brain-dead donor. Immunosuppression included antithymocyte globulins, and bolus methylprednisolone (Solu-Medrol) was used for the induction. The maintenance therapy protocol included systemic tacrolimus, mycophenolate mofetil, and prednisone. The patient discontinued the systemic steroid 15 months after surgery. Two episodes of acute rejections were observed at 105 and 810 days after surgery. These signs disappeared after pulse therapy with Solu-Medrol, titration with tacrolimus, and topical immunosuppressive creams (tacrolimus and clobetasol). However, the patient felt pain in both hips after long periods of standing 30 months after the transplantation. A pelvic radiograph and magnetic resonance imaging revealed avascular necrosis (AVN) in both hip joints. Because of the progressive worsening of the pain, the patient underwent a decompression surgery on the left hip involving a fibula bone graft. The patient underwent a right hip hemi-arthroplasty with a bipolar prosthesis 3 months later. The patient remained in good health without major complications. These findings indicate that systemic steroids and tacrolimus might be the major predisposing factors for the induction of AVN after hand allotransplantation.

Calcineurin-inhibitor induced pain syndrome - Magnetic resonance imaging and scintigraphic findings illustrated through two cases

Calcineurin-inhibitor induced pain syndrome (CIPS) is a condition characterized by lower extremity pain in patients receiving tacrolimus or cyclosporine therapy following organ transplantation. Through two cases, we demonstrate key imaging findings in CIPS with bone scintigraphy and magnetic resonance imaging (MRI), which are those of increased scintigraphic activity and marrow edema in the lower extremities, respectively. CIPS is an important condition that has characteristic imaging findings, but is unfortunately underappreciated in the radiology literature. To our knowledge, this is the first article in the radiology literature presenting two cases of CIPS, as well as the first to present both scintigraphic and MRI findings in this condition.

Decreased abundance of TRESK two-pore domain potassium channels in sensory neurons underlies the pain associated with bone metastasis

Bone metastasis–associated VEGF suppresses neuronal K + channels and increases pain in rats.

Tacrolimus-Induced Pain Syndrome After Bone Marrow Transplantation: A Case Report and Literature Review

BACKGROUND

Calcineurin-inhibitor-induced pain syndrome (CIPS), a rare complication seen in patients with bone marrow transplants, is associated with the use of cyclosporine A (CsA) or tacrolimus (FK506). This case demonstrates the successful pain control of FK506-related CIPS in a 23-year-old male patient with previously reported characteristic clinical features of CIPS in addition to neuropathic symptoms and uncharacteristic imaging findings. On day 15 after the transplantation, the patient complained of severe pain in the lower limbs. Afterwards, the patient started to complain of pain on his hands and back too. During this period, FK506 levels ranged from 9.5 to 16.1 ng/mL. All laboratory exams were normal, except for an increased level of alkaline phosphatase (141 U/L). The pain was not ameliorated by various analgesic drugs. Although MRI done for our patient showed no typical radiological signs such as bone marrow edema, CIPS was suggested based on characteristic clinical features of CIPS. Of note, our patient's pain had neuropathic pain-like characteristics, unlike the pain in previously reported patients with CIPS.

CONCLUSION

The patient was treated successfully by switching FK506 to CsA and administrating gabapentin and nifedipine. Heightened awareness of this complication after bone marrow transplants may be needed for hematologists, otherwise CIPS can result in catastrophic consequences.

Multimodal Surgical Approach for Adult Patients With Chronic Intestinal Pseudo-Obstruction: Clinical and Psychosocial Long-term Outcomes

BACKGROUND

Clinical and psychosocial outcomes of a multimodal surgical approach for chronic intestinal pseudo-obstruction were analyzed in 24 patients who were followed over a 2- to 12-year period in a single center after surgery or intestinal/multivisceral transplant (CTx).

METHODS

The main reasons for surgery were sub-occlusion in surgery and parenteral nutrition-related irreversible complications with chronic intestinal failure in CTx.

RESULTS

At the end of follow-up (February 2015), 45.5% of CTx patients were alive: after transplantation, improvement in intestinal function was observed including a tendency toward recovery of oral diet (81.8%) with reduced parenteral nutrition support (36.4%) in the face of significant mortality rates and financial costs (mean, 202.000 euros), frequent hospitalization (mean, 8.8/re-admissions/patient), as well as limited effects on pain or physical wellness.

CONCLUSIONS

Through psychological tests, transplant recipients perceived a significant improvement of mental health and emotional state, showing that emotional factors were more affected than were functional/cognitive impairment and social interaction.

Pain, fatigue and well-being one to five years after lung transplantation - a nationwide cross-sectional study

RATIONALE AND AIM

Little is known about persistent pain after lung transplantation. Therefore, the aim was to present a multidimensional assessment of self-reported pain 1-5 years after lung transplantation and its relationship with fatigue and transplant-specific well-being.

METHODS

This nationwide, cross-sectional cohort study is part of the self-management after thoracic transplantation study. A total of 117 lung recipients, all White, who were due for their annual follow-up at one (n = 35), two (n = 28), three (n = 23), four (n = 20) and 5 years (n = 11) after lung transplantation were included. We used three instruments; the Pain-O-Meter (POM), which provides information about pain intensity, sensation, location and duration, the MFI-19 fatigue instrument and the Organ Transplant Symptom and Well-being Instrument (OTSWI). Permission to carry out this study was granted by the Regional Ethical Review Board in southern Sweden (D-nr 2014-124).

RESULTS

The prevalence of pain was 51% after 1 year, 68% after 2 years, 69.5% after 3 years, 75% after 4 years and 54.5% after 5 years. Women experienced more pain than men. Lung recipients with pain reported lower well-being and higher symptom distress but were not more fatigued than those without pain.

STUDY LIMITATIONS

The limitations of this study are due to the cross-sectional design. The recruitment of patients during the study period was probably affected by the different conditions regarding staffing at the outpatient lung transplant clinic in the two thoracic transplant centres in Sweden. The slightly different approach to the care of these patients in the pre, peri and postoperative setting contributes to the heterogeneity of the study population.

CONCLUSION

Chronic bodily pain up to 5 years after lung transplantation reduces perceived well-being. Lung recipients with pain report higher symptom distress than those without pain.

Immunosuppressant Medication-Induced Lower Extremity Pain After Combined Liver and Kidney Transplant: A Case Report

Calcineurin inhibitors are imperative in the success of a transplanted organ. However, these immunosuppressants can lead to a rare complication known as calcineurin inhibitor-induced pain syndrome, which may not be recognized early and managed appropriately. We present a case of a 35-year-old woman who underwent a combined liver/kidney transplant and developed lower extremity pain while being maintained on tacrolimus. This case illustrates a patient with previously reported characteristic clinical features of calcineurin inhibitor-induced pain syndrome in addition to uncharacteristic neuropathic symptoms and imaging findings. The patient was treated successfully with gabapentin, calcitonin nasal spray, and acupuncture. Early recognition of this syndrome can help improve a patient's quality of life.

LEVEL OF EVIDENCE

V.

Renal association clinical practice guideline in post-operative care in the kidney transplant recipient

These guidelines cover the care of patients from the period following kidney transplantation until the transplant is no longer working or the patient dies. During the early phase prevention of acute rejection and infection are the priority. After around 3-6 months, the priorities change to preservation of transplant function and avoiding the long-term complications of immunosuppressive medication (the medication used to suppress the immune system to prevent rejection). The topics discussed include organization of outpatient follow up, immunosuppressive medication, treatment of acute and chronic rejection, and prevention of complications. The potential complications discussed include heart disease, infection, cancer, bone disease and blood disorders. There is also a section on contraception and reproductive issues.Immediately after the introduction there is a statement of all the recommendations. These recommendations are written in a language that we think should be understandable by many patients, relatives, carers and other interested people. Consequently we have not reworded or restated them in this lay summary. They are graded 1 or 2 depending on the strength of the recommendation by the authors, and AD depending on the quality of the evidence that the recommendation is based on.

Neurologic complications of transplantation

Major neurologic morbidity, such as seizures and encephalopathy, complicates 20-30% of organ and stem cell transplantation procedures. The majority of these disorders occur in the early posttransplant period, but recipients remain at risk for opportunistic infections and other nervous system disorders for many years. These long-term risks may be increasing as acute survival increases, and a greater number of "sicker" patients are exposed to long-term immunosuppression. Drug neurotoxicity accounts for a significant proportion of complications, with posterior reversible leukoencephalopathy syndrome, primarily associated with calcineurin inhibitors (i.e., cyclosporine and tacrolimus), being prominent as a cause of seizures and neurologic deficits. A thorough evaluation of any patient who develops neurologic symptoms after transplantation is mandatory, since reversible and treatable conditions could be found, and important prognostic information can be obtained.

Imaging findings in a child with calcineurin inhibitor-induced pain syndrome after bone marrow transplant for beta thalassemia major

Calcineurin inhibitor-induced pain syndrome is an entity recognized in patients on immunosuppressive therapy after transplantation. Diagnosis is characterized by onset of pain beginning in the setting of an elevated calcineurin-inhibitor trough level. Reducing the medication dose relieves symptoms. Imaging findings can be nonspecific, including bone marrow edema and periosteal reaction. We present the unique case of calcineurin inhibitor-induced pain syndrome in a child and review the imaging findings.

Pregabalin: A New Adjunct in Calcineurin Inhibitor Pain Syndrome Treatment

Tacrolimus and cyclosporin are calcineurin inhibitors (CIs) commonly used in organ transplants. These agents rarely cause a severe, debilitating pain syndrome of especially lower extremities, known as CI pain syndrome (CIPS). Although the pathogenesis is not well understood, neuropathic pain mechanisms have started to be discussed in the recent literature. Here, presenting a 48-year-old male with CIPS who recovered after pregabalin 150 mg twice daily, we aimed to emphasize the importance of this syndrome and offer a new approach for the treatment. This is the first report in the literature where pregabalin is demonstrated to be effective in CIPS.

The neurology of solid organ transplantation

Transplantation is the rescue treatment for end-stage organ failure with more than 110,000 solid organs transplantations performed worldwide annually. Recent advances in transplantation procedures and posttransplantation management have improved long-term survival and quality of life of transplant recipients, shifting the focus from acute perioperative critical care needs toward long-term chronic medical problems. Neurologic complications affect up to 30-60 % of solid organ transplant recipients. Common etiologies include opportunistic infections and toxicities of antirejection medications, and wide spectrum of toxic and metabolic disturbances. Most complications are common to all allograft types, but some are relatively specific for individual allograft types (e.g., central pontine myelinolysis in liver transplant recipients). Close collaboration between neurologists and other transplant team members is essential for effective management. Early recognition of complications and accurate diagnosis leading to timely treatment is essential to reduce the morbidity and improve the overall transplant outcome.

Brain natriuretic peptide constitutively downregulates P2X3 receptors by controlling their phosphorylation state and membrane localization

BACKGROUND

ATP-gated P2X3 receptors are important transducers of nociceptive stimuli and are almost exclusively expressed by sensory ganglion neurons. In mouse trigeminal ganglion (TG), P2X3 receptor function is unexpectedly enhanced by pharmacological block of natriuretic peptide receptor-A (NPR-A), outlining a potential inhibitory role of endogenous natriuretic peptides in nociception mediated by P2X3 receptors. Lack of change in P2X3 protein expression indicates a complex modulation whose mechanisms for downregulating P2X3 receptor function remain unclear.

RESULTS

To clarify this process in mouse TG cultures, we suppressed NPR-A signaling with either siRNA of the endogenous agonist BNP, or the NPR-A blocker anantin. Thus, we investigated changes in P2X3 receptor distribution in the lipid raft membrane compartment, their phosphorylation state, as well as their function with patch clamping. Delayed onset of P2X3 desensitization was one mechanism for the anantin-induced enhancement of P2X3 activity. Anantin application caused preferential P2X3 receptor redistribution to the lipid raft compartment and decreased P2X3 serine phosphorylation, two phenomena that were not interdependent. An inhibitor of cGMP-dependent protein kinase and siRNA-mediated knockdown of BNP mimicked the effect of anantin.

CONCLUSIONS

We demonstrated that in mouse trigeminal neurons endogenous BNP acts on NPR-A receptors to determine constitutive depression of P2X3 receptor function. Tonic inhibition of P2X3 receptor activity by BNP/NPR-A/PKG pathways occurs via two distinct mechanisms: P2X3 serine phosphorylation and receptor redistribution to non-raft membrane compartments. This novel mechanism of receptor control might be a target for future studies aiming at decreasing dysregulated P2X3 receptor activity in chronic pain.

Acute polyarthritis immediately after kidney transplantation: a medication-induced rheumatoid arthritis flare?

A patient with known steroid-dependent rheumatoid arthritis (RA) developed an acute symmetrical polyarthropathy of small and medium-sized joints associated with markedly elevated inflammatory markers suggestive of RA flare, on day 4 after deceased-donor renal transplantation. The patient received standard induction immunosuppression with methylprednisolone and basiliximab, and had commenced prednisolone, tacrolimus and mycophenolate mofetil. Serological investigations and joint aspirate to exclude infective causes and crystal arthropathy were unremarkable. High-dose prednisolone (50 mg daily) resulted in partial but unsustained symptomatic improvement. On suspicion of a medication-related adverse event, tacrolimus and mycophenolate mofetil were changed to cyclosporine A and azathioprine on day 16. This was followed by rapid improvement in symptoms and normalization of inflammatory markers. Unexpected sequelae in the early post-transplantation period create diagnostic and management challenges. Medication-related adverse events are not uncommon, and we speculate in this case on the potential for medication-induced immune system dysregulation stimulating disease activity in a chronic autoimmune condition after introduction of new immunosuppressants.

An unusual case of calcineurine inhibitor pain syndrome

Cyclosporine induced pain syndrome (CIPS) is a newly diagnosed complication of calcineurine inhibitors, mainly observed in solid organ and hematopoetic transplantations. The present case is a male child with steroid resistant nephrotic syndrome on low therapeutic level cyclosporine treatment. He presented with intractable and debilitating leg pain, with no reported history of previous injury or trauma. The pain was reluctant to antimicrobial and sedative treatment. MRI revealed bone marrow and soft tissue edema in the mid shaft of patient's right leg. Inspite of unusual manifestations, CIPS was suggested and cyclosporine discontinued. However, the pain did not improve and was resistant to calcium blocker. Subsequently, core decompression was performed as an unusual treatment of CIPS, revealing normal bone morphology. The pain improved rapidly and the patient was discharged a few days later.

Casein kinase II regulates N-methyl-D-aspartate receptor activity in spinal cords and pain hypersensitivity induced by nerve injury

Increased N-methyl-d-aspartate receptor (NMDAR) activity and phosphorylation in the spinal cord are critically involved in the synaptic plasticity and central sensitization associated with neuropathic pain. However, the mechanisms underlying increased NMDAR activity in neuropathic pain conditions remain poorly understood. Here we show that peripheral nerve injury induces a large GluN2A-mediated increase in NMDAR activity in spinal lamina II, but not lamina I, neurons. However, NMDAR currents in spinal dorsal horn neurons are not significantly altered in rat models of diabetic neuropathic pain and resiniferatoxin-induced painful neuropathy (postherpedic neuralgia). Inhibition of protein tyrosine kinases or protein kinase C has little effect on NMDAR currents potentiated by nerve injury. Strikingly, casein kinase II (CK2) inhibitors normalize increased NMDAR currents of dorsal horn neurons in nerve-injured rats. In addition, inhibition of calcineurin, but not protein phosphatase 1/2A, augments NMDAR currents only in control rats. CK2 inhibition blocks the increase in spinal NMDAR activity by the calcineurin inhibitor in control rats. Furthermore, nerve injury significantly increases CK2α and CK2β protein levels in the spinal cord. In addition, inhibition of CK2 or CK2β knockdown at the spinal level substantially reverses pain hypersensitivity induced by nerve injury. Our study indicates that neuropathic pain conditions with different etiologies do not share the same mechanisms, and increased spinal NMDAR activity is distinctly associated with traumatic nerve injury. CK2 plays a prominent role in the potentiation of NMDAR activity in the spinal dorsal horn and may represent a new target for treatments of chronic pain caused by nerve injury.

Casein kinase II inhibition reverses pain hypersensitivity and potentiated spinal N-methyl-D-aspartate receptor activity caused by calcineurin inhibitor

Clinically used calcineurin inhibitors, including tacrolimus (FK506) and cyclosporine A, can induce calcineurin inhibitor-induced pain syndrome (CIPS), which is characterized as severe pain and pain hypersensitivity. Increased synaptic N-methyl-D-aspartate receptor (NMDAR) activity in the spinal dorsal horn plays a critical role in the development of CIPS. Casein kinase II (CK2), a serine/threonine protein kinase, can regulate synaptic NMDAR activity in the brain. In this study, we determined whether spinal CK2 is involved in increased NMDAR activity and pain hypersensitivity caused by systemic administration of FK506 in rats. FK506 treatment caused a large increase in the amplitude of NMDAR-mediated excitatory postsynaptic currents (EPSCs) evoked by primary afferent stimulation and in the frequency of miniature EPSCs of spinal dorsal horn neurons. CK2 inhibition with either 5,6-dichloro-1-β-d-ribofuranosylbenzimidazole (DRB) or 4,5,6,7-tetrabromobenzotriazole (TBB) completely normalized the amplitude of evoked NMDAR-EPSCs of dorsal horn neurons in FK506-treated rats. In addition, DRB or TBB significantly attenuated the amplitude of NMDAR currents elicited by puff application of N-methyl-D-aspartate to dorsal horn neurons in FK506-treated rats. Furthermore, treatment with DRB or TBB significantly reduced the frequency of miniature EPSCs of spinal dorsal horn neurons increased by FK506 treatment. In addition, intrathecal injection of DRB or TBB dose-dependently reversed tactile allodynia and mechanical hyperalgesia in FK506-treated rats. Collectively, our findings indicate that CK2 inhibition abrogates pain hypersensitivity and increased pre- and postsynaptic NMDAR activity in the spinal cord caused by calcineurin inhibitors. CK2 inhibitors may represent a new therapeutic option for the treatment of CIPS.

A case report of disabling bone pain after long-term kidney transplantation

A 77-year-old man, who received a renal transplant 13 years before for IgA glomerulonephritis, was referred after he developed bilateral mid-tibial aching pain that did not improve with simple analgesia. He had recently been changed from low-dose cyclosporine to tacrolimus, but the pain did not improve when this was reversed. He had a history of focal prostatic adenocarcinoma, cryptococcal lung infection, osteoporosis treated with alendronate for 2 years and multiple squamous cell carcinomas, including one requiring left neck dissection and radiotherapy. Upon physical examination, he had gouty tophi and marked bilateral tibial tenderness but had no other clinical findings. Laboratory investigations included an elevated intact parathyroid hormone value of 7.9 pmol/L (1.6 to 6.9), bone specific alkaline phosphatase of 22 µg/L (3.7 to 20.9), urinary deoxypyridinoline/creatinine ratio of 7.2 nmol/mmol (2.5 to 5.4) and C-reactive protein. Chest X-ray and tibial X-rays were normal, but there was marrow oedema and a prominent periosteal reaction on magnetic resonance imaging. A radionuclide bone scan showed increased symmetrical, linear uptake in both tibiae and the left femur, and uptake was also noted in both clinically asymptomatic humeri. Tibial bone biopsy disclosed small deposits of poorly differentiated metastatic cancer and a follow-up chest CT revealed a lung lesion. It was concluded that the bone pain and periostitis was caused by primary lung cancer with metastatic disease to bone, and an associated hypertrophic osteoarthropathy.

Bone and mineral disorders after kidney transplantation: therapeutic strategies

Mineral and bone diseases (MBD) are common in patients with chronic kidney disease who undergo kidney transplantation. The incidence, types and severity of MBD vary according to the duration of chronic kidney disease, presence of comorbid conditions and intake of certain medications. Moreover, multiple types of pathology may be responsible for MBD. After successful reversal of uremia by kidney transplantation, many bone and mineral disorders improve, while immunosuppression, other medications, and new and existing comorbidities may result in new or worsening MBD. Chronic kidney disease is also common after kidney transplantation and may impact bone and mineral disease. In this article, we reviewed the prevalence, pathophysiology, and impact of MBD on post-transplant outcomes. We also discussed the diagnostic approach; immunosuppression management and potential treatment of MBD in kidney transplant recipients.

Poor sleep in organ transplant recipients: self-reports and actigraphy

Solid organ transplant recipients are at increased risk of poor sleep due to pharmacotherapy and co-morbidities, but sleep problems are often unrecognized and untreated. Study aims were to measure rates of occurrence, characteristics, and correlates of poor sleep in recipients. The Pittsburgh Sleep Quality Index (PSQI) and sleep parameters measured by wrist actigraphy were obtained at baseline from 143 kidney, liver, heart, lung, or pancreas transplant recipients enrolled in a psychosocial intervention trial to improve symptoms and quality of life. Rates of poor sleep were determined using accepted clinical cutoffs; 41% (58 of 143) were poor sleepers (PSQI > 8) and 36% used sleep medications in the past month. Fifteen percent reported having obstructive sleep apnea (OSA) and 4% reported restless legs syndrome (RLS). Based on actigraphy (n = 73), 69% lacked sleep efficiency (SE), 32% took >30 min to fall asleep, 88% awakened during the night for more than 30 min, and 25% slept less than six h per night. Obesity and use of psychotropics or sleep medications, and pain were independent risk factors for poor objectively measured sleep. Poor sleep is an undertreated problem in transplantation. Screening for sleep problems and behavioral therapies with sleep hygiene instruction may benefit recipients.

Calcineurin inhibitor induces pain hypersensitivity by potentiating pre- and postsynaptic NMDA receptor activity in spinal cords

Calcineurin inhibitors, such as cyclosporin A and tacrolimus (FK506), have played a pivotal role in the preservation of allograft function. However, these drugs can cause unexplained severe pain in patients, often referred to as calcineurin inhibitor-induced pain syndrome (CIPS). Although calcineurin can regulate NMDA receptor (NMDAR) activity, the causal relationship between spinal synaptic plasticity and CIPS remains unknown. In this study, we showed that systemic administration of FK506 (1.5 mg kg(-1) day(-1)) for 7 days in rats led to long-lasting nociceptive and mechanical hypersensitivity. Whole-cell patch-clamp recordings in spinal cord slices revealed that FK506 treatment caused a large increase in the amplitude of NMDAR-mediated excitatory postsynaptic currents (EPSCs) of dorsal horn neurons evoked by dorsal root stimulation. The amplitude of NMDAR currents elicited by puff NMDA application to dorsal horn neurons was also significantly greater in FK506-treated than in vehicle-treated rats. The frequency of spontaneous and miniature EPSCs in most dorsal horn neurons was profoundly increased in FK506-treated rats and was reduced by blocking NMDARs. Furthermore, blocking GluN2A or GluN2B subunits similarly reduced the amplitude of evoked EPSCs and the frequency of miniature EPSCs in dorsal horn neurons of FK506-treated rats. In addition, intrathecal injection of an NMDAR antagonist or systemic administration of memantine effectively reversed nociceptive and mechanical hypersensitivity in FK506-treated rats. Our findings indicate that calcineurin inhibition increases glutamate-mediated nociceptive input by potentiating presynaptic and postsynaptic NMDAR activity in spinal cords. NMDAR antagonists may represent a new therapeutic option for the treatment of CIPS.

Primary bone marrow oedema syndromes

MRI scanning in patients with rheumatological conditions often shows bone marrow oedema, which can be secondary to inflammatory, degenerative, infective or malignant conditions but can also be primary. The latter condition is of uncertain aetiology and it is also uncertain whether it represents a stage in the progression to osteonecrosis in some patients. Patients with primary bone marrow oedema usually have lower limb pain, commonly the hip, knee, ankle or feet. The diagnosis is one of exclusion with the presence of typical MRI findings. Treatment is usually conservative and includes analgesics and staying off the affected limb. The natural history is that of gradual resolution of symptoms over a number of months. Evidence for medical treatment is limited, but open-label studies suggest bisphosphonates may help in the resolution of pain and improve radiological findings. Surgical decompression is usually used as a last resort.

Case report: imaging features in a renal transplant patient with calcineurin inhibitor-induced pain syndrome (CIPS)

Post-transplant distal limb bone marrow edema syndrome or calcineurin inhibitor-induced pain syndrome (CIPS) is generally a self-limiting but debilitating acute pain syndrome that has been reported in 2-14 % of renal transplant recipients. The disease is extensively described in the transplant literature in patients receiving the calcineurin inhibitors cyclosporine and tacrolimus. We present a case of CIPS arising in a patient 73 days after renal allograft, review the imaging findings, and discuss proposed etiologies and differential diagnoses. To the authors' knowledge, CIPS has not been characterized as a distinct entity in the radiology literature.

Calcineurin-inhibitor pain syndrome

BACKGROUND

There has been increased recognition of calcineurin, a phosphoprotein serine/threonine phosphatase enzyme, in the regulation of many physiologic systems. Calcineurin mediates activation of lymphocytes, which play a role in immune response. Widely distributed in the central nervous system, calcinuerin also plays an important role in sensory neural function, via its role in the regulation of newly discovered 2-pore potassium channels, which greatly influence neuronal resting membrane potentials. Calcinuerin inhibition is the mechanism of action of immunomodulatory drugs such as cyclosporine and tacrolimus, which are widely used in transplantation medicine to prevent rejection. While important for immunosuppression, the use of calcineurin inhibitors has been associated with the development of a new pain syndrome called the calcineurin pain syndrome, which appears to be an untoward complication of the interruption of the physiologic function of calcineurin.

METHODS

This is a narrative review focusing on the epidemiology, pathophysiology, characterization of a newly recognized pain syndrome associated with the use of calcineurin inhibitors.

RESULTS

The use of immunosuppressants however is associated with several well-known toxicities to which the calcineurin pain syndrome can be added. The development of this syndrome most likely involves altered nociceptive processing due to the effect of calcineurin inhibition on neuronal firing, as well as effects of calcineurin on vascular tone. The most striking aspect of the treatment of this syndrome is the response to calcium channel blockers, which suggest that the effects of calcineurin inhibition on vascular tone play an important role in the development of the calcineurin pain syndrome.

CONCLUSION

The calcineurin syndrome is a newly recognized complication associated with the use of calcineurin inhibitors. There is no standard therapy at this time but anecdotal reports suggest the effectiveness of calcium channel blockers.

Immunosuppressant-related hip pain after orthotopic liver transplant

OBJECTIVES

Immunosuppressant-related hip pain can greatly affect a patient's mobility and increase the number of total hip arthroplasties. We investigated risk factors and causes of hip pain after orthotopic liver transplant.

MATERIALS AND METHODS

The medical records of 175 adult orthotopic liver transplant patients, who were followed-up for more than 2 years, were retrospectively reviewed. Data collected from the records included primary disease, medications, biochemical results, Child-Turcotte-Pugh score, death, rejection, and complications related to liver transplant.

RESULTS

A total of 11 patients (6.3%) complained of hip pain, which was diagnosed as calcineurin-inhibitor-induced pain syndrome in 4 patients (2.3%), osteonecrosis of the femoral head in 3 patients (1.7%), and osteoporosis in 2 patients (1.1%). The incidence of calcineurin-inhibitor-induced pain syndrome was related to the dosage of tacrolimus (P > .05) but independent of methylprednisolone use. The occurrence of osteonecrosis of the femoral head was independent of the dosage and early withdrawal of methylprednisolone (P > .05). Patients with methylprednisolone withdrawal within 6 months had significantly longer survival than those using methylprednisolone for more than 6 months (50 ± 15 vs 41 ± 18 mo; P = .007).

CONCLUSIONS

Calcineurin-inhibitor-induced pain syndrome and osteonecrosis of the femoral head are main causes of hip pain in adult orthotopic liver transplant patients. Osteonecrosis of the femoral head was not common, but the incidence of hip pain owing to calcineurin-inhibitor-induced pain syndrome was relatively high in orthotopic liver transplant patients. Early withdrawal of methylprednisolone could benefit the patients' survival.

Pain syndrome with stress fractures in transplanted patients treated with calcineurin inhibitors

Bone disease remains a major cause of morbidity after renal transplantation. Post-transplant osseous complications include osteoporosis and osteonecrosis, both historically associated with glucocorticoids, and a newer syndrome of bone pain associated with calcineurin inhibitors. Calcineurin inhibitor-induced pain syndrome (CIPS) is a reversible etiology of lower extremity bone pain and bone marrow edema reported in patients receiving cyclosporine or tacrolimus after solid organ or bone marrow transplantation. While the syndrome’s pathophysiology is unclear, bone insufficiency and epiphyseal impaction may play a role. We review the literature on this increasingly important post-transplant entity and describe a case illustrating the syndrome’s key features.

Familial hemiplegic migraine Ca(v)2.1 channel mutation R192Q enhances ATP-gated P2X3 receptor activity of mouse sensory ganglion neurons mediating trigeminal pain

BACKGROUND

The R192Q mutation of the CACNA1A gene, encoding for the α1 subunit of voltage-gated P/Q Ca2+ channels (Ca(v)2.1), is associated with familial hemiplegic migraine-1. We investigated whether this gain-of-function mutation changed the structure and function of trigeminal neuron P2X3 receptors that are thought to be important contributors to migraine pain.

RESULTS

Using in vitro trigeminal sensory neurons of a mouse genetic model knockin for the CACNA1A R192Q mutation, we performed patch clamp recording and intracellular Ca2+ imaging that showed how these knockin ganglion neurons generated P2X3 receptor-mediated responses significantly larger than wt neurons. These enhanced effects were reversed by the Ca(v)2.1 blocker ω-agatoxin. We, thus, explored intracellular signalling dependent on kinases and phosphatases to understand the molecular regulation of P2X3 receptors of knockin neurons. In such cells we observed strong activation of CaMKII reversed by ω-agatoxin treatment. The CaMKII inhibitor KN-93 blocked CaMKII phosphorylation and the hyperesponsive P2X3 phenotype. Although no significant difference in membrane expression of knockin receptors was found, serine phosphorylation of knockin P2X3 receptors was constitutively decreased and restored by KN-93. No change in threonine or tyrosine phosphorylation was detected. Finally, pharmacological inhibitors of the phosphatase calcineurin normalized the enhanced P2X3 receptor responses of knockin neurons and increased their serine phosphorylation.

CONCLUSIONS

The present results suggest that the CACNA1A mutation conferred a novel molecular phenotype to P2X3 receptors of trigeminal ganglion neurons via CaMKII-dependent activation of calcineurin that selectively impaired the serine phosphorylation state of such receptors, thus potentiating their effects in transducing trigeminal nociception.