Long-term efficacy and safety of inotersen in patients with hereditary transthyretin amyloid polyneuropathy with or without cardiomyopathy: post hoc analysis of NEURO-TTR open-label extension

Background/Introduction

Cardiomyopathy (CM) with associated heart failure and polyneuropathy (PN) are common manifestations of hereditary transthyretin amyloidosis (ATTRv), a progressive, debilitating, and fatal disease that results from the deposition of misfolded transthyretin (TTR) protein throughout the body. NEURO-TTR (NCT01737398) showed that inotersen, an antisense oligonucleotide inhibitor of TTR protein production, slowed the progression of PN and maintained quality of life in patients with ATTRv.

Purpose

To report efficacy and safety from the open-label extension (OLE) of the NEURO-TTR study in patients with ATTRv PN overall and in CM subgroups.

Methods

Patients who completed NEURO-TTR, enrolled in the OLE (NCT02175004), and either switched from placebo in NEURO-TTR to inotersen in the OLE (placebo-inotersen) or received inotersen in NEURO-TTR and remained on inotersen in the OLE (inotersen-inotersen) were included. Assessments included the modified Neuropathy Impairment Score +7 composite score (mNIS+7 [range –22.3 to 346.3], a measure of neuropathy with higher scores indicative of poorer function), TTR levels, and safety monitoring. Utilizing patients from Europe and North America (EU+NA) as of 28 July 2020, this post hoc analysis examined two subgroups: CM ECHO and severe CM ECHO. CM was defined as a diagnosis of ATTRv CM at study entry or all of the following criteria: a left ventricular wall thickness of ≥1.3 cm on transthoracic echocardiography at baseline, no known history of persistent hypertension (systolic blood pressure ≥150 mm Hg) within 12 months before study screening, and evaluable baseline ECHO obtained by central assessment. Severe CM was defined as an interventricular septum thickness ≥1.5 cm at baseline. Descriptive statistics are reported.

Results

In the overall population and both CM subgroups, the placebo-inotersen group demonstrated slowing of neurological disease progression compared with natural history based on NEURO-TTR placebo projection (estimated natural history will be presented). Furthermore, in the overall population and both CM subgroups, the inotersen-inotersen group demonstrated sustained benefit compared with the placebo-inotersen group (Table). Change in serum TTR levels will be presented. There have been no reports of grade 4 thrombocytopenia or acute glomerulonephritis under enhanced monitoring in patients in the EU+NA despite the increased duration of exposure. No new safety concerns were identified.

Conclusions

Inotersen treatment for >3 years slowed the progression of PN associated with ATTRv in patients with CM, including severe CM. In both subgroups, greater neurological preservation was observed in those who initiated inotersen earlier (inotersen-inotersen group), underscoring the benefits of early treatment. No new safety signals were detected in this OLE analysis; enhanced monitoring is successful in managing the risk for thrombocytopenia and acute glomerulonephritis.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): This study was sponsored by Akcea Therapeutics, an affiliate of Ionis Pharmaceuticals, Inc.

Early data on long-term efficacy and safety of inotersen in patients with hereditary transthyretin amyloidosis: a 2-year update from the open-label extension of the NEURO-TTR trial

BACKGROUND AND PURPOSE

Hereditary transthyretin (hATTR) amyloidosis causes progressive polyneuropathy resulting from transthyretin (TTR) amyloid deposition throughout the body, including the peripheral nerves. The efficacy and safety of inotersen, an antisense oligonucleotide inhibitor of TTR protein production, were demonstrated in the pivotal NEURO-TTR study in patients with hATTR polyneuropathy. Here, the long-term efficacy and safety of inotersen are assessed in an ongoing open-label extension (OLE) study.

METHODS

Patients who completed NEURO-TTR were eligible to enroll in the OLE (NCT02175004). Efficacy assessments included the modified Neuropathy Impairment Score plus seven neurophysiological tests composite score (mNIS + 7), the Norfolk Quality of Life - Diabetic Neuropathy (Norfolk QOL-DN) questionnaire total score and the Short-Form 36 Health Survey (SF-36) Physical Component Summary (PCS) score. Safety and tolerability were also assessed.

RESULTS

Overall, 97% (135/139) of patients who completed NEURO-TTR enrolled in the OLE. Patients who received inotersen for 39 cumulative months in NEURO-TTR and the OLE continued to show benefit; patients who switched from placebo to inotersen in the OLE demonstrated improvement or stabilization of neurological disease progression by mNIS + 7, Norfolk QOL-DN and SF-36 PCS. No new safety concerns were identified. There was no evidence of increased risk for grade 4 thrombocytopenia or severe renal events with increased duration of inotersen exposure.

CONCLUSION

Inotersen slowed disease progression and reduced deterioration of quality of life in patients with hATTR polyneuropathy. Early treatment with inotersen resulted in greater long-term disease stabilization than delayed initiation. Routine platelet and renal safety monitoring were effective; no new safety signals were observed.

Inotersen: new promise for the treatment of hereditary transthyretin amyloidosis

Hereditary transthyretin amyloidosis is a fatal autosomal dominant disorder characterized by deposition of transthyretin amyloid into the peripheral nervous system, heart, kidney, and gastrointestinal tract. Previous treatments using liver transplantation and small molecule stabilizers were not effective in stopping disease progression. Inotersen, a 2'-O-methyoxyethyl-modified antisense oligonucleotide, which acts by reducing the production of transthyretin, was recently demonstrated to improve disease course and quality of life in early hereditary transthyretin amyloidosis polyneuropathy in a 15-month Phase III study.

Hereditary transthyretin amyloidosis: baseline characteristics of patients in the NEURO-TTR trial

BACKGROUND

Hereditary transthyretin (ATTRm) amyloidosis is a rare, progressive and fatal disease with a range of clinical manifestations.

OBJECTIVE

This study comprehensively evaluates disease characteristics in a large, diverse cohort of patients with ATTRm amyloidosis.

METHODS

Adult patients (N = 172) with Stage 1 or Stage 2 ATTRm amyloidosis who had polyneuropathy were screened and enrolled across 24 investigative sites and 10 countries in the NEURO-TTR trial ( www.clinicaltrials.gov , NCT01737398). Medical and disease history, quality of life, laboratory data, and clinical assessments were analyzed.

RESULTS

The NEURO-TTR patient population was diverse in age, disease severity, TTR mutation, and organ involvement. Twenty-seven different TTR mutations were present, with Val30Met being the most common (52%). One third of patients reported early onset disease (before age 50) and the average duration of neuropathy symptoms was 5.3 years. Symptoms affected multiple organs and systems, with nearly 70% of patients exhibiting broad involvement of weakness, sensory loss, and autonomic disturbance. Over 60% of patients had cardiomyopathy, with highest prevalence in the United States (72%) and lowest in South America/Australasia (33%). Cardiac biomarker NT-proBNP correlated with left ventricular wall thickness (p<.001). Quality of life, measured by Norfolk QoL-DN and SF-36 patient-reported questionnaires, was significantly impaired and correlated with disease severity.

CONCLUSIONS

Baseline data from the NEURO-TTR trial demonstrates ATTRm amyloidosis as a systemic disease with deficits in multiple organs and body systems, leading to decreased quality of life. We report concomitant presentation of polyneuropathy and cardiomyopathy in most patients, and early involvement of multiple body systems.

Genotype-phenotype study in patients with valosin-containing protein mutations associated with multisystem proteinopathy

Mutations in valosin-containing protein (VCP), an ATPase involved in protein degradation and autophagy, cause VCP disease, a progressive autosomal dominant adult onset multisystem proteinopathy. The goal of this study is to examine if phenotypic differences in this disorder could be explained by the specific gene mutations. We therefore studied 231 individuals (118 males and 113 females) from 36 families carrying 15 different VCP mutations. We analyzed the correlation between the different mutations and prevalence, age of onset and severity of myopathy, Paget's disease of bone (PDB), and frontotemporal dementia (FTD), and other comorbidities. Myopathy, PDB and FTD was present in 90%, 42% and 30% of the patients, respectively, beginning at an average age of 43, 41, and 56 years, respectively. Approximately 9% of patients with VCP mutations had an amyotrophic lateral sclerosis (ALS) phenotype, 4% had been diagnosed with Parkinson's disease (PD), and 2% had been diagnosed with Alzheimer's disease (AD). Large interfamilial and intrafamilial variation made establishing correlations difficult. We did not find a correlation between the mutation type and the incidence of any of the clinical features associated with VCP disease, except for the absence of PDB with the R159C mutation in our cohort and R159C having a later age of onset of myopathy compared with other molecular subtypes.

Inotersen Treatment for Patients with Hereditary Transthyretin Amyloidosis

BACKGROUND

Hereditary transthyretin amyloidosis is caused by pathogenic single-nucleotide variants in the gene encoding transthyretin ( TTR) that induce transthyretin misfolding and systemic deposition of amyloid. Progressive amyloid accumulation leads to multiorgan dysfunction and death. Inotersen, a 2'- O-methoxyethyl-modified antisense oligonucleotide, inhibits hepatic production of transthyretin.

METHODS

We conducted an international, randomized, double-blind, placebo-controlled, 15-month, phase 3 trial of inotersen in adults with stage 1 (patient is ambulatory) or stage 2 (patient is ambulatory with assistance) hereditary transthyretin amyloidosis with polyneuropathy. Patients were randomly assigned, in a 2:1 ratio, to receive weekly subcutaneous injections of inotersen (300 mg) or placebo. The primary end points were the change in the modified Neuropathy Impairment Score+7 (mNIS+7; range, -22.3 to 346.3, with higher scores indicating poorer function; minimal clinically meaningful change, 2 points) and the change in the score on the patient-reported Norfolk Quality of Life-Diabetic Neuropathy (QOL-DN) questionnaire (range, -4 to 136, with higher scores indicating poorer quality of life). A decrease in scores indicated improvement.

RESULTS

A total of 172 patients (112 in the inotersen group and 60 in the placebo group) received at least one dose of a trial regimen, and 139 (81%) completed the intervention period. Both primary efficacy assessments favored inotersen: the difference in the least-squares mean change from baseline to week 66 between the two groups (inotersen minus placebo) was -19.7 points (95% confidence interval [CI], -26.4 to -13.0; P<0.001) for the mNIS+7 and -11.7 points (95% CI, -18.3 to -5.1; P<0.001) for the Norfolk QOL-DN score. These improvements were independent of disease stage, mutation type, or the presence of cardiomyopathy. There were five deaths in the inotersen group and none in the placebo group. The most frequent serious adverse events in the inotersen group were glomerulonephritis (in 3 patients [3%]) and thrombocytopenia (in 3 patients [3%]), with one death associated with one of the cases of grade 4 thrombocytopenia. Thereafter, all patients received enhanced monitoring.

CONCLUSIONS

Inotersen improved the course of neurologic disease and quality of life in patients with hereditary transthyretin amyloidosis. Thrombocytopenia and glomerulonephritis were managed with enhanced monitoring. (Funded by Ionis Pharmaceuticals; NEURO-TTR ClinicalTrials.gov number, NCT01737398 .).

Assessing mNIS+7Ionis and international neurologists' proficiency in a familial amyloidotic polyneuropathy trial

INTRODUCTION

Polyneuropathy signs (Neuropathy Impairment Score, NIS), neurophysiologic tests (m+7_Ionis ), disability, and health scores were assessed in baseline evaluations of 100 patients entered into an oligonucleotide familial amyloidotic polyneuropathy (FAP) trial.

METHODS

We assessed: (1) Proficiency of grading neurologic signs and correlation with neurophysiologic tests, and (2) clinometric performance of modified NIS+7 neurophysiologic tests (mNIS+7_Ionis ) and its subscores and correlation with disability and health scores.

RESULTS

The mNIS+7_Ionis sensitively detected, characterized, and broadly scaled diverse polyneuropathy impairments. Polyneuropathy signs (NIS and subscores) correlated with neurophysiology tests, disability, and health scores. Smart Somatotopic Quantitative Sensation Testing of heat as pain 5 provided a needed measure of small fiber involvement not adequately assessed by other tests.

CONCLUSIONS

Specially trained neurologists accurately assessed neuropathy signs as compared to referenced neurophysiologic tests. The score, mNIS+7_Ionis , broadly detected, characterized, and scaled polyneuropathy abnormality in FAP, which correlated with disability and health scores. Muscle Nerve 56: 901-911, 2017.

[Craniosynostosis and strabismus]

Craniosynostosis(CS), the premature fusion of cranial sutures leading to an abnormal shape and precocious maturity of skull, is classified into Non-syndromic Craniosynostosis (NSC) and Syndromic Craniosynostoses(SC).NCS only has different abnormality of skull according to which cranial suture is involved while extra malformation of midface and limbs present in SCS. Common SCS contains Crouzon Syndrome, Apert Syndrome, Pfeiffer Sydrome, and etc. The clinical manifestation of CS includes malformation of skull, intracranial hypertension, brain hernia, developmental disorder of cerebral function, strabismus, and etc, while SCS has more complex manifestation. Along with the improvement of multidisciplinary cooperation, the ophthalmic complication of CS, like strabismus, is recognised by oculists gradually. This review is summarizing the clinical manifestation, complicated strabismus, pathogenesis and multidisciplinary cure of CS. (Chin J Ophthalmol, 2016, 52: 626-630).

A randomized controlled trial of methotrexate for patients with generalized myasthenia gravis

OBJECTIVE

To determine the steroid-sparing effect of methotrexate (MTX) in patients with symptomatic generalized myasthenia gravis (MG).

METHODS

We performed a 12-month multicenter, randomized, double-blind, placebo-controlled trial of MTX 20 mg orally every week vs placebo in 50 acetylcholine receptor antibody-positive patients with MG between April 2009 and August 2014. The primary outcome measure was the prednisone area under the dose-time curve (AUDTC) from months 4 to 12. Secondary outcome measures included 12-month changes of the Quantitative Myasthenia Gravis Score, the Myasthenia Gravis Composite Score, Manual Muscle Testing, the Myasthenia Gravis Quality of Life, and the Myasthenia Gravis Activities of Daily Living.

RESULTS

Fifty-eight patients were screened and 50 enrolled. MTX did not reduce the month 4-12 prednisone AUDTC when compared to placebo (difference MTX - placebo: -488.0 mg, 95% confidence interval -2,443.4 to 1,467.3, p = 0.26); however, the average daily prednisone dose decreased in both groups. MTX did not improve secondary measures of MG compared to placebo over 12 months. Eight participants withdrew during the course of the study (1 MTX, 7 placebo). There were no serious MTX-related adverse events. The most common adverse event was nonspecific pain (19%).

CONCLUSIONS

We found no steroid-sparing benefit of MTX in MG over 12 months of treatment, despite being well-tolerated. This study demonstrates the challenges of conducting clinical trials in MG, including difficulties with recruitment, participants improving on prednisone alone, and the need for a better understanding of outcome measure variability for future clinical trials.

CLASSIFICATION OF EVIDENCE

This study provides Class I evidence that for patients with generalized MG MTX does not significantly reduce the prednisone AUDTC over 12 months of therapy.

Effect of trapped energetic particles on the resistive wall mode

A stability analysis for the resistive wall mode is studied in the presence of trapped energetic particles (EPs). When the EPs' beta exceeds a critical value, a fishbonelike bursting mode (FLM) with an external kink eigenstructure can exist. This offers the first analytic interpretation of the experimental observations [Phys. Rev. Lett. 103, 045001 (2009)]. The mode-particle resonances for the FLM and the q=1 fishbone occur in different regimes of the precession frequency of EPs. In certain ranges of the plasma rotation speed and the EPs' beta, a mode conversion can occur between the resistive wall mode and FLM.

Do A-waves help predict intravenous immunoglobulin response in multifocal motor neuropathy without block?

INTRODUCTION

Are there electrophysiological findings that predict response to intravenous immunoglobulin (IVIg) in patients with lower motor neuron (LMN) syndromes without multifocal conduction block (MCB)?

METHODS

We enrolled 9 patients with LMN syndromes without MCB to receive 18 weeks of IVIg therapy. Response was measured at weeks 2 and 18 using the Appel Amyotrophic Lateral Sclerosis (AALS) score (includes grip and pincer strength measures), ALS Functional Rating Scale (ALSFRS), and electrophysiological measures, including motor unit estimates (MUNEs).

RESULTS

No change occurred in AALS or ALSFRS scores posttreatment. Grip/pincer strength increased in 7 patients (P = 0.028) after initial treatment (responders); 2 showed no improvement (non-responders). No electrophysiological measure changed after treatment in either group but MUNEs trended higher (P = 0.055). "Abnormal A-waves" (complex, repetitive biphasic, or present in multiple nerves) occurred in pretreatment studies more often in responders (P = 0.028).

DISCUSSION

"Abnormal A-waves" may signal IVIg-responsive LMN syndromes even if conduction block is absent.

Patterns of neuropathy and autonomic failure in patients with amyloidosis

OBJECTIVE

To define the clinical patterns of peripheral neuropathy and autonomic testing abnormalities in patients with amyloidosis.

PATIENTS AND METHODS

A retrospective chart review was conducted of 65 patients who had biopsy-proven amyloidosis and autonomic function testing between January 1, 1985, and December 31, 1997, at Mayo Clinic's site in Rochester, MN. Patients were required to have neurologic evaluation, autonomic reflex screening, and tissue confirmation of amyloidosis.

RESULTS

We identified 5 clinical patterns of peripheral neuropathy: (1) generalized autonomic failure and polyneuropathy with pain (40 patients [62%]), (2) generalized autonomic failure and polyneuropathy without pain (11 [17%]), (3) isolated generalized autonomic failure (7 [11%]), (4) polyneuropathy without generalized autonomic failure (4 [6%]), and (5) generalized autonomic failure and small-fiber (ie, autonomic and somatic C-fiber) neuropathy (3 [5%]). Moderately severe generalized autonomic failure, involving adrenergic, cardiovagal, or sudomotor domains, was found in all patients, including those without clinically manifested autonomic failure. The diagnosis of amyloidosis was delayed in patients who did not have initial symptoms of pain or generalized autonomic failure (48 months to diagnosis in patients with polyneuropathy without autonomic failure vs 12 months to diagnosis in patients with autonomic failure and small-fiber neuropathy; P=.57).

CONCLUSION

Physicians should test for symptoms of generalized autonomic failure in patients who have peripheral neuropathy of unknown origin. Autonomic testing may give abnormal results in patients without overt symptoms of autonomic failure. Early recognition of autonomic failure may lead to earlier diagnosis of the underlying pathogenesis of amyloidosis, as well as earlier treatment for patients with this condition.

Botulinum toxin type A in primary palmar hyperhidrosis: randomized, single-blind, two-dose study

BACKGROUND

Primary palmar hyperhidrosis is characterized by excessive sweating due to increased sympathetic cholinergic sudomotor nerve traffic to the palmar surface of the hands. Clinical studies suggest that intradermal injections of botulinum toxin are effective in the treatment of palmar hyperhidrosis.

OBJECTIVES

To establish the effectiveness of intradermal botulinum toxin in reducing hyperhidrosis, to determine the most effective dose of toxin, and to examine its effect on muscle strength.

METHODS

In a prospective, single blind, randomized trial, 24 patients with severe palmar hyperhidrosis received either a low (50 U) or a high dose (100 U) of botulinum toxin type A (Botox, Allergan) injected intradermally in 20 sites in each palm.

RESULTS

Following injection with either dose, iodine starch test revealed a significant decrease in sweating within the first month. Six months after injection, the anhidrotic effect was still evident in two thirds of the patients in both groups. Handgrip strength was not affected with either dose but finger pinch strength, 2 weeks after the injection, decreased 23 +/- 27% with 50 U (p < 0.05) and 40 +/- 21% with 100 U (p < 0.001). Pinch strength improved gradually but 6 months after treatment it was still 7-11% lower than at baseline.

CONCLUSIONS

Both 50 and 100 U of botulinum toxin type A, injected intradermally in each hand, decreased sweating in patients with primary hyperhidrosis for at least 2 months in all the patients, and 6 months in most patients. Weakness in the intrinsic muscles of the hand was observed.

HIV-associated peripheral neuropathy: epidemiology, pathophysiology and treatment

Peripheral neuropathy is the most frequent neurological complication associated with human immunodeficiency virus type 1 (HIV) infection and advanced acquired immunodeficiency syndrome (AIDS). There are at least 6 patterns of HIV-associated peripheral neuropathy, although these diagnoses are often overlooked or misdiagnosed. Distal symmetrical polyneuropathy (DSP) is the most common form of peripheral neuropathy in HIV infection. DSP occurs mainly in patients with advanced immunosuppression and may also be secondary to the neurotoxicity of several antiretroviral agents. Treatment of painful DSP is primarily symptomatic, while pathogenesis-based therapies are under investigation. Reduction or discontinuation of neurotoxic agents should be considered if possible. Inflammatory demyelinating polyneuropathy (IDP) can present in an acute or chronic form. The acute form may occur at the time of primary HIV infection or seroconversion. Cerebrospinal fluid lymphocytic pleocytosis (10 to 50 cells/mm3) is helpful in the diagnosis of HIV-associated IDP. Treatment consists of immunomodulatory therapy. Progressive polyradiculopathy (PP) most commonly occurs in advanced immunosuppression and usually is caused by cytomegalovirus (CMV) infection. Rapidly progressive flaccid paraparesis, radiating pain and paresthesias, areflexia and sphincter dysfunction are the cardinal clinical features. Rapid diagnosis and treatment with anti-CMV therapy are necessary to prevent irreversible neurological deficits resulting from nerve root necrosis. Mononeuropathy multiplex (MM) that occurs in early HIV infection is characterised by self-limited sensory and motor deficits in the distribution of individual peripheral nerves. In advanced HIV infection, multiple nerves in two or more extremities or cranial nerves are affected. Treatment includes immunomodulation or anti-CMV therapy. Autonomic neuropathy may be caused by central or peripheral nervous system abnormalities. Treatment is supportive with correction of metabolic or toxic causes. Diffuse infiltrative lymphocytosis syndrome (DILS) presents as a Sjögren's-like disorder with CD8 T cell infiltration of multiple organs. Antiretroviral therapy and steroids may be effective treatments.

Effect of simple analgesics on quantitative sensation test threshold

Twenty individuals underwent quantitative sensation testing (QST) before and after 1 dose of aspirin, acetaminophen, or acetaminophen with codeine to determine the effect of analgesics on QST results. There was no significant change from baseline when mean QST results after placebo were compared to mean QST results after analgesics. We conclude that the effect of small doses of simple analgesics on QST results is either not present or is too small to necessitate withholding analgesics before sensory testing.

Heat sensitivity of sensory fibers in carpal tunnel syndrome

Elevations in temperature may produce conduction block in demyelinated neurons. A well-described phenomenon in multiple sclerosis, it has also been reported in some patients with inflammatory demyelinating polyneuropathies. We used carpal tunnel syndrome (CTS) as a model to study the effect of heat on nerves with focal demyelination secondary to chronic compression. Compound motor and sensory responses were measured in 12 CTS patients and 12 normal subjects at 32 degrees C and with heating to 42 degrees C. Changes in relative motor response amplitude and area were similar for both normal subjects and CTS patients. In CTS patients, however, sensory response amplitude and area decreased 34.3% and 48.9%, significantly more than the 25.2% and 39.1% reductions in normal subjects (P=0.021 and P=0.018 respectively). We hypothesize that these reductions in response amplitude are secondary to the occurrence of heat-induced conduction block in demyelinated sensory neurons.

High-temperature repetitive nerve stimulation in myasthenia gravis

High temperature enhances the decrement on repetitive nerve stimulation (RNS) in patients with myasthenia gravis (MG). However, the limit of this phenomenon at high temperature is unknown. Three-hertz ulnar RNS was performed in 7 patients with MG at a skin temperature of 32 degrees C and then with the hand in a 44 degrees C water bath. At 32 degrees C, the mean decrement preactivation was 5% (range, 0-24%); after 1 min of exercise, the mean decrement reached a maximum of 11% (range, 1-34%) 2 min postactivation. At a hand temperature of 42 degrees C, the mean decrement preactivation was 17% (range, 0-65%); after exercise, the mean decrement reached a maximum of 29% (range, 5-74%) 1 min postactivation. In 3 subjects, RNS was normal at 32 degrees C, but a definite decrement developed with heating. These findings demonstrate that very high temperature can improve the sensitivity of ulnar RNS for postsynaptic neuromuscular transmission defects.

Cooperative breeding and monogamy in prairie voles: influence of the sire and geographical variation

Mammalian monogamy is characterized by pair bonding and a relative absence of sexual dimorphism in body size. Alloparental behaviour is a characteristic of mammalian cooperative breeding systems. Studies of prairie voles, Microtus ochrogaster, from stock captured in a resource-abundant habitat in Illinois have supported the assumption that this species is a monogamous, cooperative breeder, while other studies of prairie voles from a more arid habitat in Kansas have called this assumption into question. We hypothesized that reported differences between these populations represented true intraspecific variation. Patterns of sexual dimorphism in body size, partner preferences and parental contact behaviour were compared in prairie voles from stocks originating in Illinois or Kansas. Both Illinois and Kansas voles showed a strong preference for a familiar partner, which is suggestive of monogamy. Sexual dimorphism in body size was observed in Kansas, but not Illinois voles. Illinois voles displayed significantly higher levels of parental contact behaviour than did voles from Kansas. When animals from Illinois and Kansas were crossed, the expression of parental contact behaviour of the 'hybrid' offspring followed the pattern seen in the population of origin of the sire. Removal of the sire prior to the birth of the litter increased alloparenting in Kansas voles, but removal of the sire was associated with lower levels of alloparenting in Illinois voles. Thus, some traits associated with the social system may show intraspecific variation and can be influenced by the presence or absence of the sire during rearing. Copyright 1998 The Association for the Study of Animal Behaviour. Copyright 1998 The Association for the Study of Animal Behaviour.

Neuroimaging findings in patients on immunosuppressive therapy: experience with tacrolimus toxicity

OBJECTIVE

The purpose of this study is to describe the neuroimaging (CT and MR imaging) findings in liver transplant patients who develop severe neurologic side effects during immunosuppressive therapy with tacrolimus and to correlate these findings with clinical signs and tacrolimus levels in blood.

SUBJECTS AND METHODS

Brain CT and/or MR imaging was performed on six patients who developed neurologic symptoms while receiving tacrolimus in the post-transplant period. All patients were evaluated by the neurology staff, and imaging studies were independently interpreted by three neuroradiologists. Trough tacrolimus levels in blood were measured with the IMX immunoassay and were correlated with neurologic symptoms and imaging findings.

RESULTS

Imaging abnormalities were observed in five of six patients during the course of their neurologic illnesses. For each patient, neurologic symptoms began when the tacrolimus level in blood was at a peak, exceeding the therapeutic limit in all but one case. In five patients, neurologic symptoms eventually resolved after the tacrolimus dose was reduced or after the drug was stopped. Multifocal low attenuation of white matter was the predominant finding seen on CT images, and matching hyperintense white matter foci were observed on long-TR MR images. In three patients, clinical recovery was accompanied by reversal of the white matter abnormalities seen on CT and MR images.

CONCLUSION

Immunosuppressive therapy with tacrolimus may produce neurologic side effects that are associated with brain CT and MR imaging abnormalities. Resolution of symptoms and reversal of imaging findings occur when the tacrolimus dose is reduced.

MR imaging of spinal cord and vertebral body infarction

PURPOSE

To study the usefulness of MR in the evaluation of spinal cord infarctions and associated findings.

MATERIALS AND METHODS

MR examinations of 12 patients (10 men and two women) were reviewed retrospectively. Onset of symptoms of spinal cord ischemia was abrupt in all patients; MR was performed 8 hr to 4 months after onset. Contrast-enhanced MR was performed in four of the patients.

RESULTS

Abnormal MR findings of the spinal cord included abnormal cord signal (11 of 12), best demonstrated on T2-weighted images, and morphologic changes (cord enlargement during the acute phase in nine patients and cord atrophy during the chronic phase in two), best demonstrated on T1-weighted images. Vascular abnormalities (aortic) were detected by MR in four of the 12 patients. Three of these four patients also had abnormal bone marrow signal, predominantly in the anterior half (one) or in multiple areas near the endplate and/or deep medullary portion of the vertebral body involving several vertebrae (two). T1-weighted images were not sensitive in detecting signal changes in either the bone marrow (two of three) or spinal cord (nine of 12). Enhanced MR imaging was performed in four patients (two in the acute phase and two in the chronic phase) and showed diffuse enhancement of the spinal cord proximal to a relatively unenhancing distal conus in one of the two patients imaged during the acute phase. No abnormal enhancement was noted in the other three patients.

CONCLUSION

MR is a useful means of detecting spinal cord infarction and associated vascular and bony changes. The patterns of bone marrow abnormalities reflect the underlying pathophysiology of the blood supply to the spinal cord and bone. The associated vascular and bone marrow abnormalities serve as additional information for the diagnosis of spinal cord infarction.