Could a herpesvirus mimic tacrolimus-induced leukoencephalopathy?

Cyclosporine-Associated Leukoencephalopathy in Organ Transplant Recipients: Experience of Three Clinical Cases

Leukoencephalopathy is a structural alteration of cerebral white matter mainly involving damage to myelin. Several reports have linked cyclosporine (CsA) with this alteration. The clinical features vary from qualitative alterations of consciousness to neurological deficits. Magnetic resonance imaging (MRI) of the brain demonstrates the damage to the white matter, which is essential for the differential diagnosis. We describe three clinical cases of leukoencephalopathy. The first case is a 43-year-old man received a cadaveric kidney transplant using immunosuppression with of mycophenolate mofetil, prednisone, and CsA. Four months later he developed meningism and bilateral sixth nerve palsy. The second case is a 50-year-old man with a cadaveric kidney transplant received immunosuppressive treatment with azathioprine and prednisone. As a result of gouty arthritis of the ankle, azathioprine was replaced with CsA to allow addition of allopurinol. Two weeks later he developed confusion and personality changes. The third case is a 16-year-old man received a orthotopic liver transplant. Postoperatively he suffered generalized tonic-clonic seizures. In all patients the CsA levels were toxic and signs of neurological alterations were present on MRI. All patients recovered rapidly after CsA withdrawal.

Reversible Leukoencephalopathy Syndrome Associated to Leukopenia in a Chronic Hemodialysis Patient

Reversible leukoencephalopathy syndrome (RLS) is a rare brain disorder, characterized by diffuse attenuation of cerebral white matter, which has been most commonly observed in transplant patients receiving calcineurin inhibitors or in patients with severe hypertension. We report an episode of RLS in a 22-year-old male patient on chronic hemodialysis with well-controlled moderate hypertension who presented with de novo headache and generalized seizures. Cranial magnetic resonance image (MRI) revealed multiple areas of increased signal intensity in the white matter on T2-weighed images which resolved spontaneously at subsequent MRIs. White blood cell count showed leucopenia with normal CD4 count at flow cytometry. A viral etiology could not be demonstrated. Reversible leukoencephaolopathy syndrome symptoms remitted within 72 h but leukopenia persisted over 10 months. The patient received a kidney transplant 15 months after RLS onset and has received cyclosporine since the second post-transplant day. No recurrence of RLS symptoms has been observed. The etiology of the MRI changes in the present case seemed not to be either vasogenic or cytotoxic.

Impairment of the blood-brain barrier can result in tacrolimus-induced reversible leucoencephalopathy following heart transplantation

Fatal leucoencephalopathy is a rare calcineurin inhibitor-related complication, especially in kidney and liver transplant recipients. The only means of clinical management reported so far is the discontinuation or reduction in the calcineurin inhibitor. We herein report a case of a 37-yr-old male who developed leucoencephalopathy 12 wk after heart transplantation and recovered after stabilization of metabolism and arterial blood pressure. The findings in this case support the hypothesis that tacrolimus-associated neurotoxicity is severely increased by an impairment of the blood-brain barrier. Withdrawal of tacrolimus was not necessary while other causes of endothelial injury were treated successfully.

Human herpesvirus-6 and -7 in transplantation

Infections with the beta-herpesviruses human herpesvirus-6 (HHV-6) and human herpesvirus-7 (HHV-7) are ubiquitous in childhood. The immunosuppression secondary to organ or bone marrow transplantation together with posttransplantation management may favour viral replication and reactivation. HHV-6 and -7 induce immunosuppression by targeting lymphocytes, natural killer cells and monocytes. HHV-6 is commonly detected posttransplantation but variability in definitions of clinical syndromes related to this virus and detection methods have complicated understanding of the clinical relevance of HHV-6 posttransplantation. Clinical symptoms associated with HHV-6 include febrile illness, pneumonitis, hepatitis, encephalitis and bone marrow suppression. However, the majority of HHV-6 infections are asymptomatic. The incidence of HHV-7 infection and its clinical manifestations posttransplantation are even less well characterised. In addition, HHV-6 and HHV-7 are related to CMV disease or acute graft-versus-host disease and, indirectly, to increases in resource utilisation. Based on the potential relevance of these two beta-herpesviruses in transplant recipients, further studies are required to establish their real impact in transplantation. For this, sensitive and specific molecular diagnostic techniques allowing for the rapid detection and quantitation of virus and for the analysis of susceptibility to current antiviral agents are required.

Immunosuppressive-associated leukoencephalopathy in organ transplant recipients

Immunosuppressive-associated leukoencephalopathy is a significant complication of cyclosporine (CsA) or tacrolimus therapy. However, the precise time of onset, role of putative risk factors, differences, if any, in presentation in various types of organ transplantation and outcome of this entity, remain poorly defined. Fifty cases of immunosuppressive-associated leukoencephalopathy reported in the literature in organ transplant recipients, were reviewed. Of 50 cases, 31 occurred in liver, 8 in renal, 6 in lung, and 5 in heart transplant recipients. Median time to onset was 28 days (range 3-1512 days); 82% occurred within 90 days of transplantation. Lesions tended to occur earlier in the liver transplant recipients, compared with other organ transplant recipients (median 9 vs. 29 days, P=.19). Seizures 74%, altered mental status 50%, and visual abnormalities 28% were the most frequently presenting features. Ten percent of the patients had fever with no documented source of infection. Systemic hypertension (P=.001), and lesions in the presence of therapeutic drug levels (P=.11) were more likely to occur with CsA than tacrolimus. Neuroimaging and clinical abnormalities were reversible on cessation or reduction of CsA or tacrolimus in all but two cases. Resolution of neurologic signs/symptoms occurred a median of 4 days and neuroimaging abnormalities in a median of 20 days on reduction/cessation of the drug. Immunosuppressive-associated leukoencephalopathy is a unique entity that can usually be diagnosed on the basis of its distinctive time of onset, and clinical and neuroimaging characteristics, and it is potentially reversible if promptly diagnosed. Despite identical clinical presentation of this syndrome in the recipients of CsA and tacrolimus, above noted variations in risk factors suggest that a difference in pathophysiologic mechanism may exist.