Are we creating a new phenotype? Physiological barriers and ethical considerations in the treatment of hereditary transthyretin-amyloidosis

Hereditary transthyretin (TTR) amyloidosis (ATTRv) is an autosomal dominant, systemic disease transmitted by amyloidogenic mutations in the TTR gene. To prevent the otherwise fatal disease course, TTR stabilizers and mRNA silencing antisense drugs are currently approved treatment options. With 90% of the amyloidogenic protein produced by the liver, disease progression including polyneuropathy and cardiomyopathy, the two most prominent manifestations, can successfully be halted by hepatic drug targeting or-formerly-liver transplantation. Certain TTR variants, however, favor disease manifestations in the central nervous system (CNS) or eyes, which is mostly associated with TTR production in the choroid plexus and retina. These compartments cannot be sufficiently reached by any of the approved medications. From liver-transplanted patients, we have learned that with longer lifespans, such CNS manifestations become more relevant over time, even if the underlying TTR mutation is not primarily associated with such. Are we therefore creating a new phenotype? Prolonging life will most likely lead to a shift in the phenotypic spectrum, enabling manifestations like blindness, dementia, and cerebral hemorrhage to come out of the disease background. To overcome the first therapeutic limitation, the blood-brain barrier, we might be able to learn from other antisense drugs currently being used in research or even being approved for primary neurodegenerative CNS diseases like spinal muscular atrophy or Alzheimer's disease. But what effects will unselective CNS TTR knock-down have considering its role in neuroprotection? A potential approach to overcome this second limitiation might be allele-specific targeting, which is, however, still far from clinical trials. Ethical standpoints underline the need for seamless data collection to enable more evidence-based decisions and for thoughtful consenting in research and clinical practice. We conclude that the current advances in treating ATTRv amyloidosis have become a meaningful example for mechanism-based treatment. With its great success in improving patient life spans, we will still have to face new challenges including shifts in the phenotype spectrum and the ongoing need for improved treatment precision. Further investigation is needed to address these closed barriers and open questions.

Real-world outcomes in non-endemic hereditary transthyretin amyloidosis with polyneuropathy: a 20-year German single-referral centre experience

BACKGROUND

Hereditary transthyretin amyloidosis is caused by pathogenic variants in the TTR gene and typically manifests, alongside cardiac and other organ dysfunctions, with a rapidly progressive sensorimotor and autonomic polyneuropathy (ATTRv-PN) leading to severe disability. While most prospective studies have focussed on endemic ATTRv-PN, real-world data on non-endemic, mostly late-onset ATTRv-PN are limited.

METHODS

This retrospective study investigated ATTRv-PN patients treated at the Amyloidosis Centre of Heidelberg University Hospital between November 1999 and July 2020. Clinical symptoms, survival, prognostic factors and efficacy of treatment with tafamidis were analysed. Neurologic outcome was assessed using the Coutinho ATTRv-PN stages, and the Peripheral Neuropathy Disability (PND) score.

RESULTS

Of 346 subjects with genetic TTR variants, 168 patients had symptomatic ATTRv-PN with 32 different TTR variants identified. Of these, 81.6% had the late-onset type of ATTRv-PN. Within a mean follow-up period of 4.1 ± 2.8 years, 40.5% of patients died. Baseline plasma N-terminal prohormone of brain natriuretic peptide (NT-proBNP) ≥900 ng/l (HR 3.259 [1.421-7.476]; p = .005) was the main predictor of mortality in multivariable analysis. 64 patients were treated with tafamidis and presented for regular follow-up examinations. The therapeutic benefit of tafamidis was more pronounced when treatment was started early in ATTRv-PN stage 1 (PND scores II vs. I; HR 2.718 [1.258-5.873]; p = .011).

CONCLUSIONS

In non-endemic, mostly late-onset ATTRv-PN, cardiac involvement assessed by NT-proBNP is a strong prognosticator for overall survival. Long-term treatment with tafamidis is safe and efficacious. Neurologic disease severity at the start of treatment is the main predictor for ATTRv-PN progression on tafamidis.

Chance or challenge, spoilt for choice? New recommendations on diagnostic and therapeutic considerations in hereditary transthyretin amyloidosis with polyneuropathy: the German/Austrian position and review of the literature

Hereditary transthyretin amyloidosis is caused by pathogenic variants (ATTR_v) in the TTR gene. Alongside cardiac dysfunction, the disease typically manifests with a severely progressive sensorimotor and autonomic polyneuropathy. Three different drugs, tafamidis, patisiran, and inotersen, are approved in several countries, including the European Union and the United States of America. By stabilizing the TTR protein or degrading its mRNA, all types of treatment aim at preventing amyloid deposition and stopping the otherwise fatal course. Therefore, it is of utmost importance to recognize both onset and progression of neuropathy as early as possible. To establish recommendations for diagnostic and therapeutic procedures in the follow-up of both pre-symptomatic mutation carriers and patients with manifest ATTR_v amyloidosis with polyneuropathy, German and Austrian experts elaborated a harmonized position. This paper is further based on a systematic review of the literature. Potential challenges in the early recognition of disease onset and progression are the clinical heterogeneity and the subjectivity of sensory and autonomic symptoms. Progression cannot be defined by a single test or score alone but has to be evaluated considering various disease aspects and their dynamics over time. The first-line therapy should be chosen based on individual symptom constellations and contra-indications. If symptoms worsen, this should promptly implicate to consider optimizing treatment. Due to the rareness and variability of ATTR_v amyloidosis, the clinical course is most importantly directive in doubtful cases. Therefore, a systematic follow-up at an experienced center is crucial to identify progression and reassure patients and carriers.

Magnetization transfer ratio quantifies polyneuropathy in hereditary transthyretin amyloidosis

Objective

To quantify peripheral nerve lesions in symptomatic and asymptomatic hereditary transthyretin amyloidosis with polyneuropathy (ATTRv‐PNP) by analyzing the magnetization transfer ratio (MTR) of the sciatic nerve, and to test its potential as a novel biomarker for macromolecular changes.

Methods

Twenty‐five patients with symptomatic ATTRv‐PNP, 30 asymptomatic carriers of the mutant transthyretin gene (mutTTR), and 20 age‐/sex‐matched healthy controls prospectively underwent magnetization transfer contrast imaging at 3 Tesla. Two axial three‐dimensional gradient echo sequences with and without an off‐resonance saturation rapid frequency pulse were conducted at the right distal thigh. Sciatic nerve regions of interest were manually drawn on 10 consecutive axial slices in the images without off‐resonance saturation, and then transferred to the corresponding slices that were generated by the sequence with the off‐resonance saturation pulse. Subsequently, the MTR and cross‐sectional area (CSA) of the sciatic nerve were evaluated. Detailed neurologic and electrophysiologic examinations were conducted in all ATTRv‐PNP patients and mutTTR‐carriers.

Results

Sciatic nerve MTR and CSA reliably differentiated between ATTRv‐PNP, mutTTR‐carriers, and controls. MTR was lower in ATTRv‐PNP (26.4 ± 0.7; P < 0.0001) and in mutTTR‐carriers (32.6 ± 0.8; P = 0.0005) versus controls (39.4 ± 2.1), and was also lower in ATTRv‐PNP versus mutTTR‐carriers (P = 0.0009). MTR correlated negatively with the NIS‐LL and positively with CMAPs and SNAPs. CSA was higher in ATTRv‐PNP (34.3 ± 1.7 mm³) versus mutTTR‐carriers (26.0 ± 1.1 mm³; P = 0.0005) and versus controls (20.4 ± 1.2 mm³; P < 0.0001). CSA was also higher in mutTTR‐carriers versus controls.

Interpretation

MTR is a novel imaging marker that can quantify macromolecular changes in ATTRv‐PNP and differentiate between symptomatic ATTRv‐PNP and asymptomatic mutTTR‐carriers and correlates with electrophysiology.

Transthyretin-Amyloidose (ATTR-Amyloidose): Empfehlungen zum Management in Deutschland und Österreich

Die Transthyretin-Amyloidose (ATTR-Amyloidose) ist eine seltene, rasch verlaufende neurodegenerative Erkrankung, verursacht durch Mutationen im Transthyretin-Gen. Aufgrund der Seltenheit ist sie wenig bekannt mit der Folge, dass die Diagnose in vielen Fällen nicht oder für eine effektive Therapie zu spät gestellt wird. Therapeutisch steht seit Anfang der 1990er-Jahre die Lebertransplantation zur Verfügung, seit 2011 der oral einzunehmende Transthyretinstabilisator Tafamidis. Weitere Substanzen sind in der klinischen Prüfung oder stehen vor der Zulassung. Hierzu zählen die gentherapeutischen Substanzen Inotersen und Patisiran, die auf dem Boden der RNA-Interferenz wirken, für die Behandlung der Polyneuropathie und Tafamidis zur Behandlung der Kardiomyopathie bei ATTR-Amyloidosen. Die vorliegende Arbeit deutschsprachiger Experten gibt Empfehlungen zu Diagnostik, Management und Therapie von ATTR-Amyloidosen und soll helfen, diese erbliche, heute aber gut behandelbare, Erkrankung einem weiteren Kreis von Ärzten bekannt zu machen.

MR neurography biomarkers to characterize peripheral neuropathy in AL amyloidosis

Objective

To detect, localize, and quantify peripheral nerve lesions in amyloid light chain (AL) amyloidosis by magnetic resonance neurography (MRN) in correlation with clinical and electrophysiologic findings.

Methods

We prospectively examined 20 patients with AL-polyneuropathy (PNP) and 25 age- and sex-matched healthy volunteers. After detailed neurologic and electrophysiologic testing, the patient group was subdivided into mild and moderate PNP. MRN in a 3.0 tesla scanner with anatomical coverage from the lumbosacral plexus and proximal thigh down to the tibiotalar joint was performed by using T2-weighted and dual-echo 2-dimensional sequences with spectral fat saturation and a 3-dimensional, T2-weighted inversion recovery sequence. Besides evaluation of nerve T2-weighted signal, detailed quantification of nerve injury by morphometric (nerve caliber) and microstructural MRN markers (proton spin density, T2 relaxation time) was conducted.

Results

Nerve T2-weighted signal increase correlated with disease severity: moderate (420.2 ± 60.1) vs mild AL-PNP (307.2 ± 17.9; p = 0.0003) vs controls (207.0 ± 6.4; p < 0.0001). Proton spin density was also higher in moderate (tibial: 525.5 ± 53.0; peroneal: 553.6 ± 64.5; sural: 492.0 ± 56.6) and mild AL-PNP (tibial: 431.6 ± 22.0; peroneal: 457.6 ± 21.7; sural: 404.8 ± 25.2) vs controls (tibial: 310.5 ± 14.1; peroneal: 313.6 ± 11.6; sural: 261.7 ± 11.0; p < 0.0001 for all nerves). T2 relaxation time was elevated in moderate AL-PNP only (tibial: p = 0.0106; peroneal: p = 0.0070; sural: p = 0.0190). Tibial nerve caliber was higher in moderate (58.0 ± 8.8 mm3) vs mild AL-PNP (46.5 ± 2.5 mm3; p = 0.008) vs controls (39.1 ± 1.2 mm3; p < 0.0001).

Conclusions

MRN detects and quantifies peripheral nerve injury in AL-PNP in vivo with high sensitivity and in close correlation with the clinical stage. Quantitative parameters are feasible new imaging biomarkers for the detection of early AL-PNP and might help to monitor microstructural nerve tissue changes under treatment.

Sural nerve injury in familial amyloid polyneuropathy: MR neurography vs clinicopathologic tools

OBJECTIVE

To detect and quantify lesions of the small-caliber sural nerve (SN) in symptomatic and asymptomatic transthyretin familial amyloid polyneuropathy (TTR-FAP) by high-resolution magnetic resonance neurography (MRN) in correlation with electrophysiologic and histopathologic findings.

METHODS

Twenty-five patients with TTR-FAP, 10 asymptomatic carriers of the mutated transthyretin gene (mutTTR), and 35 age- and sex-matched healthy controls were prospectively included in this cross-sectional case-control study. All participants underwent 3T MRN with high-structural resolution (fat-saturated, T2-weighted, and double-echo sequences). Total imaging time was ≈45 minutes per patient. Manual SN segmentation was performed from its origin at the sciatic nerve bifurcation to the lower leg with subsequent evaluation of quantitative microstructural and morphometric parameters. Additional time needed for postprocessing was ≈1.5 hours per participant. Detailed neurologic and electrophysiologic examinations were conducted in the TTR group.

RESULTS

T2 signal and proton spin density (ρ) reliably differentiated between TTR-FAP (198.0 ± 13.3, 429.6 ± 15.25), mutTTR carriers (137.0 ± 16.9, p = 0.0009; 354.7 ± 21.64, p = 0.0029), and healthy controls (90.0 ± 3.4, 258.2 ± 9.10; p < 0.0001). Marked differences between mutTTR carriers and controls were found for T2 signal (p = 0.0065) and ρ (p < 0.0001). T2 relaxation time was higher in patients with TTR-FAP only (p = 0.015 vs mutTTR carriers, p = 0.0432 vs controls). SN caliber was higher in patients with TTR-FAP vs controls and in mutTTR carriers vs controls (p < 0.0001). Amyloid deposits were histopathologically detectable in 10 of 14 SN specimens.

CONCLUSIONS

SN injury in TTR-FAP is detectable and quantifiable in vivo by MRN even in asymptomatic mutTTR carriers. Differences in SN T2 signal between controls and asymptomatic mutTTR carriers are derived mainly from an increase of ρ, which overcomes typical limitations of established diagnostic methods as a highly sensitive imaging biomarker for early detection of peripheral nerve lesions.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that MRN accurately identifies asymptomatic mutTTR carriers.

Lenalidomide/melphalan/dexamethasone in newly diagnosed patients with immunoglobulin light chain amyloidosis: results of a prospective phase 2 study with long-term follow up

Chemotherapy in light chain amyloidosis aims to normalize the involved free light chain in serum, which leads to an improvement, or at least stabilization of organ function in most responding patients. We performed a prospective single center phase 2 trial with 50 untreated patients not eligible for high-dose treatment. The treatment schedule comprised 6 cycles of oral lenalidomide, melphalan and dexamethasone every 4 weeks. After 6 months, complete remission was achieved in 9 patients (18%), very good partial remission in 16 (32%) and partial response in 9 (18%). Overall, organ response was observed in 24 patients (48%). Hematologic and cardiac toxicities were predominant adverse events. Mortality at 3 months was low at 4% (n=2) despite the inclusion of 36% of patients (n=18) with cardiac stage Mayo 3. After a median follow-up of 50 months, median overall and event-free survival were 67.5 months and 25.1 months, respectively. We conclude that the treatment of lenalidomide, melphalan and dexamethasone is very effective in achieving a hematologic remission, organ response and, consecutively, a long survival in transplant ineligible patients with light chain amyloidosis. However, as toxicity and tolerability are the major problems of a 3-drug regimen, a strict surveillance program is necessary and sufficient to avoid severe toxicities. clinicaltrials.gov Identifier: 00883623 (Eudract2008-001405-41).

In vivo detection of nerve injury in familial amyloid polyneuropathy by magnetic resonance neurography

See Morrow and Reilly (doi:10.1093/awu396) for a scientific commentary on this article.

Transthyretin familial amyloid polyneuropathy is a rare, autosomal-dominant multisystem disorder. Kollmer et al. show that high-resolution MR-neurography can quantify and localize lower limb nerve injury in vivo, both in symptomatic patients and in asymptomatic mutation carriers. Lesions appear at thigh-level and are predominantly proximal, although symptoms start and prevail distally.

Transthyretin familial amyloid polyneuropathy is a rare, autosomal-dominant inherited multisystem disorder usually manifesting with a rapidly progressive, axonal, distally-symmetric polyneuropathy. The detection of nerve injury by nerve conduction studies is limited, due to preferential involvement of small-fibres in early stages. We investigated whether lower limb nerve-injury can be detected, localized and quantified in vivo by high-resolution magnetic resonance neurography. We prospectively included 20 patients (12 male and eight female patients, mean age 47.9 years, range 26–66) with confirmed mutation in the transthyretin gene: 13 with symptomatic polyneuropathy and seven asymptomatic gene carriers. A large age- and sex-matched cohort of healthy volunteers served as controls (20 male and 20 female, mean age 48.1 years, range 30–73). All patients received detailed neurological and electrophysiological examinations and were scored using the Neuropathy Impairment Score–Lower Limbs, Neuropathy Deficit and Neuropathy Symptom Score. Magnetic resonance neurography (3 T) was performed with large longitudinal coverage from proximal thigh to ankle-level and separately for each leg (140 axial slices/leg) by using axial T₂-weighted (repetition time/echo time = 5970/55 ms) and dual echo (repetition time 5210 ms, echo times 12 and 73 ms) turbo spin echo 2D sequences with spectral fat saturation. A 3D T₂-weighted inversion-recovery sequence (repetition time/echo time 3000/202 ms) was acquired for imaging of the spinal nerves and lumbar plexus (50 axial slice reformations). Precise manual segmentation of the spinal/sciatic/tibial/common peroneal nerves was performed on each slice. Histogram-based normalization of nerve–voxel signal intensities was performed using the age- and sex-matched control group as normative reference. Nerve-voxels were subsequently classified as lesion-voxels if a threshold of >1.2 (normalized signal-intensity) was exceeded. At distal thigh level, where a predominant nerve–lesion–voxel burden was observed, signal quantification was performed by calculating proton spin density and T₂-relaxation time as microstructural markers of nerve tissue integrity. The total number of nerve–lesion voxels (cumulated from proximal-to-distal) was significantly higher in symptomatic patients (20 405 ± 1586) versus asymptomatic gene carriers (12 294 ± 3199; P = 0.036) and versus controls (6536 ± 467; P < 0.0001). It was also higher in asymptomatic carriers compared to controls (P = 0.043). The number of nerve–lesion voxels was significantly higher at thigh level compared to more distal levels (lower leg/ankle) of the lower extremities (f-value = 279.22, P < 0.0001). Further signal-quantification at this proximal site (thigh level) revealed a significant increase of proton-density (P < 0.0001) and T₂-relaxation-time (P = 0.0011) in symptomatic patients, whereas asymptomatic gene-carriers presented with a significant increase of proton-density only. Lower limb nerve injury could be detected and quantified in vivo on microstructural level by magnetic resonance neurography in symptomatic familial amyloid polyneuropathy, and also in yet asymptomatic gene carriers, in whom imaging detection precedes clinical and electrophysiological manifestation. Although symptoms start and prevail distally, the focus of predominant nerve injury and injury progression was found proximally at thigh level with strong and unambiguous lesion-contrast. Imaging of proximal nerve lesions, which are difficult to detect by nerve conduction studies, may have future implications also for other distally-symmetric polyneuropathies.

Cerebral amyloid angiopathy--an underdiagnosed entity in younger adults with lobar intracerebral hemorrhage?

Cerebral amyloid angiopathy (CAA) is a progressive microvascular amyloidosis affecting the small- and medium-sized arterioles and the capillaries of brain parenchyma and leptomeninges, and is recognized as a cause of lobar intracerebral hemorrhage (ICH). We report two patients who experienced recurrent ICH due to CAA at an age of 37 (A) and 42 (B) years, respectively. The classic and modified Boston criteria for the diagnosis of CAA include an age limit of 55 years if no biopsy or postmortem examination is performed; CAA is typically not considered in the differential diagnosis of lobar ICH in younger patients. We assume that sporadic CAA is an underdiagnosed entity in younger adults with lobar ICH.

Familial amyloidotic polyneuropathy: current and emerging treatment options for transthyretin-mediated amyloidosis

Transthyretin familial amyloid polyneuropathy (TTR-FAP) is a fatal clinical disorder characterized by extracellular deposition of abnormal fibrils derived from misfolded, normally soluble transthyretin (TTR) molecules. The disease is most commonly caused by a point mutation within the TTR gene inherited in an autosomal dominant fashion. Over 100 of such mutations have been identified, leading to destabilization of the physiological TTR tetramer. As a result, many monomers originate with a tendency for spontaneous conformational changes and self-aggregation. The main clinical feature of TTR-FAP is progressive sensorimotor and autonomic neuropathy. In the beginning, this polyneuropathy predominantly involves small unmyelinated nerve fibers with the result of dissociated sensory loss disproportionately affecting sensation of pain and temperature. Autonomic neuropathy typically accompanies sensory deficits early in the disease course. The symptoms include orthostatic hypotension, constipation alternating with diarrhea, erectile dysfunction, anhydrosis, and urinary retention or incontinence. Later, involvement of motor fibers causes rapidly progressive weakness and gait disturbances. In addition to the peripheral nervous system, the heart and the gut are frequently affected. Onset of symptoms is bimodal, with one peak at age 33 years (early onset) and another distinct peak in the sixth decade of life (late onset). The course of TTR-FAP is uniformly progressive and fatal. Death occurs an average of 10.8 years after the onset of symptoms in Portuguese patients, and 7.3 years in late-onset Japanese patients. Common causes include cachexia, cardiac failure, arrhythmia, and secondary infections. Liver transplantation is the standard therapy for patients who are in a clinical condition good enough to tolerate this intervention because it stops progression of neuropathy by removing the main source of mutant TTR. Recently, orally administered tafamidis meglumine has been approved by European authorities for treatment of FAP. The substance has been shown to stabilize the TTR tetramer, thereby improving the outcome of patients with TTR-FAP. Various other strategies have been studied in vitro to prevent TTR amyloidosis, including gene therapy, immunization, dissolution of TTR aggregates, and free radical scavengers, but none of them is ready for clinical use so far.

Transthyretin valine-94-alanine, a novel variant associated with late-onset systemic amyloidosis with cardiac involvement

A 63-year-old Caucasian male, diagnosed with dilated cardiomyopathy in 1993, remained clinically stable for several years. In 2003, a marked increase of N-terminal pro-natriuretic peptide serum level (611 ng/ml to 4926 ng/ml) was observed; left ventricular (LV) septum thickness was 10 mm. In addition, sensorimotor polyneuropathy and autonomic dysfunction occurred. Further progression of heart failure occurred despite unchanged systolic LV function. Endomyocardial biopsy in 2006 revealed transthyretin amyloidosis by Congo red and immunohistochemical staining, as well as Val94Ala substitution by transthyretin gene analysis. Cardiac amyloid deposition was quantified by technetium-99m-3,3-diphosphono-1,2-propanodicarboxylic acid (99mTc-DPD) scintigraphy. Mutational search of the relatives (n = 1) was unremarkable. The transthyretin Val94Ala mutation is characterized by sensorimotor polyneuropathy, autonomic dysfunction, and gastrointestinal and cardiac involvement with amyloid. This mutation is an addition to the growing spectrum of transthyretin mutations with late onset of clinical symptoms, but noteworthy because of progressive, finally disabling disease course. Final clinical assessment of severity of cardiac involvement in the present patient is rendered complex by possible concomitant or preceding idiopathic dilated cardiomyopathy.

[Critical illness myopathy in intensive care patients. Pathogenetic concepts and clinical management]

Intensive care patients are at increased risk of developing sepsis with multi-organ failure during treatment (severe sepsis) possibly leading to complications of the central and peripheral nervous system. Among these, septic encephalopathy, critical illness polyneuropathy (CIP) and critical illness myopathy (CIM) are the most important. Neuromuscular complications in particular are difficult to diagnose as they mostly become apparent only when sedation has ceased and the awakening patient experiences difficulties in weaning from the respirator and reduced voluntary strength. CIP and CIM are generally self-limiting, however, they greatly prolong ICU stay and rehabilitation, thus nowadays also imposing a real budget threat. The diagnostics, especially the differentiation between CIM and CIP is difficult and a multi-disciplinary approach involving ICU physicians, anesthetists and neurologists is needed. Our knowledge of the causes of the primary ICU myopathy, although rapidly evolving during recent years, is still in its infancy and specific treatment of CIM is not yet available. The present overview summarizes insights into clinical and new diagnostic strategies for early detection of neuromuscular dysfunction in ICU patients. This article focuses on current concepts and results revealing the pathomechanism(s) of CIM and some simple therapeutic or preventive measures have been deduced which are summarized and discussed.

Genetic microheterogeneity of human transthyretin detected by IEF

Mutations of the human transthyretin (TTR) gene have attracted medical interest as a cause of amyloidosis. Recently, we have described in detail an electrophoretic procedure with PAGE followed by IEF in urea gradients for the study of the microheterogeneity of TTR monomers (Altland, K., Winter, P., Sauerborn, M. K., Electrophoresis 1999, 20, 1349-1364). In this paper, we present a study on 49 different mutations of TTR including 33 that result in electrically neutral amino acid substitutions. The aims of the investigation were to test the sensitivity of the procedure to detect TTR variants in patients with TTR amyloidosis and their relatives and to identify some common characteristics that could explain the amyloidogenicity of these variants. We found that all tested amyloidogenic mutations could be detected by our method with the exception of those for which the corresponding variant was absent in plasma samples. Most of the electrically neutral amyloidogenic TTR variants had in common a reduced conformational stability of monomers by the activity of protons and urea. For three variants, e.g. TTR-F64L, TTR-I107V and TTR-V122I, the monomers had a conformational stability close to that of normal monomers but we found experimental and structural arguments for a weakening of the monomer-monomer contact. All types of amyloidogenic mutations affected the stability of TTR tetramers.

[Interdisciplinary guidelines on diagnosis and treatment for extracerebral amyloidoses--published by the German Society of Amyloid Diseases (www.amyloid.de)]

Within the past 10 years, a new range of knowledge has been achieved in the field of amyloidosis, especially with regard to pathogenesis, diagnosis and therapy. Amyloidosis leads to variable and distinct symptoms and is caused by different underlying conditions. Some amyloidoses are acquired secondary to a chronic condition; others are caused by genetic mutations. Amyloid and amyloidosis occur more frequently than they are perceived. Among the frequent localized forms are the cerebral amyloidosis linked to Alzheimer disease (AD) and the pancreatic amyloidosis linked to diabetes mellitus. Among the most frequent systemic (extracerebral) forms is AL amyloidosis, which often has a poor prognosis and if untreated can rapidly lead to death. Systemic amyloidosis that happen at infancy are mainly AA amyloidosis that can progress to death already at early or at middle adulthood. Amyloidosis can be treated but therapeutic success significantly depends upon early diagnosis and proper classification of the amyloid type. It is mandatory that differential diagnosis demonstrate the presence of amyloid and clearly identify the type of the disease. Development of methods and techniques have contributed to improvements in the diagnosis and treatment. Early diagnosis and proper classification of amyloid is decisive for therapeutic options and upon them depend quality of life and mortality. The therapeutic spectrum is various and includes organ transplantation, chemotherapy, and anti-inflammatory strategies. Gene therapy and biological active substances have to be considered in the near future.

Indications for Liver Transplantation in Patients with Amyloidosis: A Single-Center Experience with 11 Cases

Familial amyloidotic polyneuropathy (FAP) is an inherited disorder with the systemic deposition of amyloid fibrils containing mutant transthyretin variants. The mutant form of transthyretin amyloidosis is produced mainly in the liver. Successful liver transplantation (LTx) could eliminate the source of the variant transthyretin molecule, and is now the only known curative treatment. The aim of this study is to evaluate the results of LTx for FAP at the University of Heidelberg. Eleven patients who underwent LTx between 1985 and 2004 with the diagnosis of FAP were evaluated. Of 11 patients, seven (64%) were male and four (36%) were female. The mean age was 49.5 years (range 27-70). Met 30 (n=5) was the most common type of amyloidosis followed by Arg 50 (n=3), Val 107 (n=2), and Phe 33 (n=1). All of the patients were selected for LTx and Domino LTx was performed in six patients. The majority (80%) of the patients with type Met 30 amyloidosis are alive, whereas in other types of amyloidosis only 33% are living. This finding emphasizes better prognosis of Met 30 variant of FAP in comparison to other variants such as Arg 50, Val 107, and Phe 33. After LTx, improvement of clinical symptoms (completely or partially) was observed in six patients (55%). In conclusion, LTx is considered as the only therapeutic alternative in patients with amyloidosis accompanied by hepatic synthesis of the amyloid protein. The most important risk factors for LTx can be predicted by assessing the nutritional condition of the patient, the duration of the disease, and the amyloid variant. Therefore, precise diagnostic measures are required before listing a patient for LTx. Domino LTx is an acceptable form of LTx that can preserve the pool of organ donors. In order to stop the progression of FAP, LTx would be justified in a subgroup of patients with amyloidosis. Based on our results, we support the idea that the effectiveness of extended preoperative period before LTx or the transplantation of other transthyretin variants other than Met 30 is questionable.

Indications for High-Dose Chemotherapy with Autologous Stem Cell Support in Patients with Systemic Amyloid Light Chain Amyloidosis

Systemic amyloid light chain amyloidosis is a protein conformation disorder caused by a clonal plasma cell dyscrasia. Symptoms result from fibrillar extracellular deposits in kidney, heart, liver, gut, peripheral nervous system and other tissues. The deposits disrupt organ function and ultimately lead to death. The prognosis of systemic amyloid light chain (AL) amyloidosis is poor; less than 5% of all patients survive 10 years or longer. Using conventional chemotherapy, the median survival could be prolonged by 4 months. Treatment with high-dose melphalm (HDM) and autologous stem cell transplantation (ASCT) of selected patients has been shown to arrest and even to reverse the disease course. This procedure however remains controversial because treatment related mortality (TRM) in AL amyloidosis is substantially higher (15-40%) than in multiple myeloma (<5%). Here we review recent results of ASCT, eligibility criteria for HDM and report our own treatment results in 41 patients.

Understanding critical illness myopathy: approaching the pathomechanism

Myopathies occurring in critically ill patients have gained increasing interest during the past years. For the patient, they represent a crucial factor for prolonged intensive care unit treatment and secondary complications. Critical illness myopathies (CIMs) seem to be related to various pathogenic factors. Among those, the septic inflammatory response syndrome seems to play a major role. It has been suggested that, similar to sepsis-related multiorgan failure, CIM might be considered a failure of the organ muscle. Muscle function might be impaired by proposed "myotoxic" humoral factors. These could be endogenously produced during the innate immune response to sepsis. This article follows up recent evidence for such active fractions in the blood serum of CIM patients. To explain muscle weakness in CIM, serum fractions acutely modified membrane excitability and subcellular Ca2+ regulation in an animal model. From the differential serum effects, early-phase CIM seems to involve a reduction in the overall force generation in muscle but also a compensation by the membrane, increasing the excitability. Different animal models will help to elucidate the underlying mechanisms accounting for the specific proteolytic activities found in different forms of CIM. CIM represents a systemic rather than a local disorder. Humoral factors might initiate the local reaction of skeletal muscle clinically seen as muscle weakness, altered excitability, and proteolysis of contractile proteins. Establishing the interactions in the excitation-contraction cascade in CIM is a challenging task, not only to clarify its pathomechanism but also to deduce clinical interventions.

Critical illness myopathy serum fractions affect membrane excitability and intracellular calcium release in mammalian skeletal muscle

The pathogenesis of myopathies occurring in critically ill patients (critical illness myopathy, CIM) is poorly understood. Both local and systemic responses to sepsis and other severe insults to the body are presumed to be involved but the precise mechanisms by which muscle function is impaired are far from clear. To elucidate such mechanisms we investigated the effects of blood serum fractions (5 kDa to 100 kDa molecular weight cut-off, MWCO) from patients with CIM and from control persons on membrane and contractile functions in intact mammalian single skeletal muscle fibres and chemically skinned fibre bundles. In intact fibres, resting membrane potentials were less negative when exposed to CIM serum fractions compared with control serum fractions. Half-width and maximum rise time of action potentials (AP) were smaller in CIM serum low MWCO fractions vs. control serum. Peak amplitudes of fast inward sodium currents (I(Na)) were increased by low MWCO-CIM fractions compared with control sera fractions. Additionally, voltage dependent inactivation of I(Na) was shifted towards more positive potentials by high MWCO fractions of CIM sera. In skinned fibres, pCa-force relations were similar in CIM and control serum fractions but peak force of Ca2+ induced force transients was decreased by low MWCO-CIM vs. control serum fractions. Our results (i) provide the first evidence that serum from CIM patients affects membrane excitability and the excitation-contraction coupling process at the level of the sarcoplasmic reticulum Ca2+ release of mammalian muscle fibres and (ii) also show that even control serum fractions "per se" alter the response to important physiological membrane and contractility parameters compared with physiological saline.

[Niemann-Pick disease type C--a neurometabolic disease through disturbed intracellular lipid transport]

Niemann-Pick disease type C (NPC) is a rare, neurovisceral lipid storage disorder caused by genetic defects in lipid transporting proteins. It is distinct from Niemann-Pick types A and B (sphingomyelin lipidoses) and displays genetic (mutations in the NPC1 or NPC2[=HE1] gene), biochemical, and clinical heterogeneity. Late infantile to juvenile forms of NPC predominate and are characterised by atypical behaviour, ataxia, dysarthria, dysphagia, dystonia, cataplexy, vertical gaze palsy, splenomegaly, and dementia. In adult variants, psychosis and dementia are common, and dysarthria, ataxia, splenomegaly, and vertical gaze palsy are further facultative signs. Routine laboratory results including serum cholesterol are normal. In bone marrow smears, sea-blue histiocytes are often demonstrated and foam cells sometimes seen. The diagnosis is confirmed by detecting free cholesterol accumulation in perinuclear granules (lysosomes) and reduced cholesterol esterification after challenge with exogenous low-density lipoprotein in fibroblasts. Alternatively or additionally, mutational analysis can be performed. Treatment is restricted to symptomatic measures, since there is no specific therapy.

[Neurologic sequelae of chronic alcoholism]

Chronic alcohol abuse causes several distinct diseases of the central and peripheral nervous system. Widely known are the alcohol withdrawal syndrome, alcohol-induced epileptic seizures, alcoholic polyneuropathy and myopathy, and Wernicke's encephalopathy. Beside these complications, less common syndromes have been identified, including Marchiafava-Bignami syndrome, subacute encephalopathy with seizure activity (SESA syndrome), and tobacco alcohol amblyopia. These syndromes can be diagnosed by their characteristic features in cranial MRI or in EEG. Moreover, certain disorders in which alcohol abuse is only indirectly involved in the pathogenesis are more frequent in alcoholics than in nonalcoholics. In daily practice, it is important to differentiate these disorders when encountering patients with chronic alcohol abuse.

[Hereditary amyloidoses associated with transthyretin mutations]

Hereditary amyloidoses form a clinically and genetically heterogeneous group of autosomal-dominantly inherited diseases characterized by the ubiquitous extracellular deposit of fibrillary aggregated proteins. Main components of these unsolvable deposits are physiologic proteins that became amyloidogenic through genetically determined conformation changes resulting in an increase in beta-sheet structures. In the vast majority of cases, the offending protein is variant transthyretin (TTR), of which over 80 mutations are known. Among these, substitution of valine by methionine in position 30 (TTR-Met30) is the most commonly encountered. In typical cases, TTR amyloidoses present with polyneuropathy, carpal tunnel syndrome, autonomic insufficiency, cardiomyopathy, and gastrointestinal features, occasionally accompanied by vitreous opacities and renal insufficiency. Rarely, involvement of the leptomeningeal or meningovascular structures dominates the clinical picture. The clinical expression is highly variable, with many atypical manifestations. Asymptomatic mutations have recently been identified. The age of onset varies greatly between early adulthood and old age. Late-onset atypical manifestations and occurrence of asymptomatic carriers render identification of affected family members difficult despite autosomal-dominant inheritance. Orthotopic liver transplantation (OLT) is the only effective therapy available today. This OLT stops progression of the disease, which is otherwise invariably fatal, by removal of the main production site of the amyloidogenic protein. However, cardiac involvement may progress after OLT for unknown reasons. The indication for OLT and its success depend on the grade of cardiovascular and autonomic dysfunction at the time of surgery, age, comorbidity, and type of mutation. Alternative treatment modalities with drugs stabilizing the native tetrameric conformation of TTR, inhibiting fibril formation or breaking beta-sheet structures, are currently being intensively studied.

Neurological complications of sepsis: critical illness polyneuropathy and myopathy

Sepsis may cause not only failure of parenchymal organs but can also cause damage to peripheral nerves and skeletal muscles. It is now recognized that sepsis-mediated disorders of the peripheral nerves and the muscle, called critical illness polyneuropathy (CIP) and critical illness myopathy, are responsible for weakness and muscle atrophy occurring de novo in intensively treated patients. CIP represents an acute axonal neuropathy that develops during treatment of severely ill patients and remits spontaneously, once the critical condition is under control. The course is monophasic and self-limiting. Among the critical illness myopathies, three main types have been identified: a non-necrotizing "cachectic" myopathy (critical illness myopathy in the strict sense), a myopathy with selective loss of myosin filaments ("thick filament myopathy") and an acute necrotizing myopathy of intensive care. Clinical manifestations of both critical illness myopathies and CIP include delayed weaning from the respirator, muscle weakness, and prolonging of the mobilization phase. The pathogenesis of these neuromuscular complications of sepsis is not understood in detail but most authors assume that the inflammatory factors that mediate systemic inflammatory response and multiple organ failure are closely involved. In thick filament myopathy and acute necrotizing myopathy, administration of steroids and neuromuscular blocking agents may act as triggers. Specific therapies have not been discovered. Stabilization of the underlying critical condition and elimination of sepsis appear to be of major importance. Steroids and muscle relaxants should be avoided or administered at the lowest dose possible.

Critical illness polyneuropathy

Critical illness polyneuropathy is a self-limited acute axonal neuropathy that develops during treatment of severely ill patients and remits spontaneously once the critical condition is under control. Clinical manifestations include muscle weakness and atrophy, delayed weaning from the respirator, and prolongation of the mobilization phase. The pathogenesis is not understood in detail but most authors assume that the inflammatory cascade that mediates the systemic inflammatory response and multiple organ failure play a pivotal role. This review summarizes current knowledge of this common neuropathic complication during intensive care treatment.

Proper receptor signalling in a mutant catfish gonadotropin-releasing hormone receptor lacking the highly conserved Asp(90) residue

The negatively charged side chain of an Asp residue in transmembrane domain 2 is likely to play an important role in receptor signalling since it is highly conserved in the whole family of G protein-coupled receptors, except in mammalian gonadotropin-releasing hormone (GnRH) receptors. In this paper we show that the conserved Asp(90) of the catfish GnRH receptor can be substituted by a neutral Asn(90) without abolishing receptor signalling if another negatively charged Glu(93) is introduced in a proximal region of the receptor interior, thereby mimicking the Glu(90)-Lys(121) salt bridge of mammalian GnRH receptors.

Critical illness polyneuropathy: clinical findings and cell culture assay of neurotoxicity assessed by a prospective study

OBJECTIVE

First, to evaluate the role of typical intensive care-related conditions like sepsis, prolonged ventilation, drug effects and metabolic disorders in the pathogenesis of critical illness polyneuropathy (CIP); second, to investigate the possible significance of patient serum neurotoxicity assessed by an in vitro cytotoxicity assay with respect to CIP development.

DESIGN

Prospective study.

SETTING

Neurological intensive care unit.

PATIENTS AND PARTICIPANTS

Twenty-eight patients who were on mechanical respiratory support for at least 4 days during a 21-month study period.

RESULTS

Diagnosis of CIP was established by clinical and electrophysiological examination in 16 (57%) of 28 patients. Patients were investigated on days 4, 8 and 14 of mechanical ventilation. Two of 16 CIP patients had clinical signs of polyneuropathy at initial examination. Factors that correlated significantly with the development of CIP were: the multiple organ failure score on day 8 of ventilation, the total duration of respiratory support, the presence of weaning problems and the manifestation of complicating sepsis and/or lung failure. The in vitro toxicity assay showed serum neurotoxicity in 12 of 16 CIP patients. Electrophysiological investigations yielded false positive results of the toxicity assay in six patients (not developing CIP) and false negative results in four patients (developing clinical and electrophysiological signs of CIP). Statistical analysis did not reveal a significant correlation between the diagnosis of CIP and the finding serum neurotoxicity.

CONCLUSION

The results support the hypothesis of a multi-factorial aetiopathogenesis of CIP. We observed serum neurotoxicity in the majority of CIP patients, indicating the possible involvement of a so far unknown, low-molecular-weight neurotoxic agent in CIP pathogenesis.

Transthyretin-associated neuropathic amyloidosis. Pathogenesis and treatment

Hereditary amyloidoses form a clinically and genetically heterogeneous group of autosomal dominantly inherited diseases characterized by the deposit of insoluble protein fibrils in the extracellular matrix. They typically present with polyneuropathy, carpal tunnel syndrome, autonomic insufficiency, and cardiomyopathy and gastrointestinal features, occasionally accompanied by vitreous opacities and renal insufficiency. Other phenotypes are characterized by nephropathy, gastric ulcers, cranial nerve dysfunction, and corneal lattice dystrophy. Rarely, involvement of the leptomeningeal or cerebral structures dominates the clinical picture. The age at onset is as early as 17 and as late as 78 years. The basic constituents of amyloid fibers are physiologic proteins that have become amyloidogenic through genetically determined conformation changes. Mutated transthyretin (TTR), formerly termed prealbumin, is the most frequent offender in hereditary amyloidosis. Orthotopic liver transplantation (OLT) stops the progression of the disease, which is otherwise invariably fatal, by removing the main production site of amyloidogenic protein. The indications for OLT and its success depend on the grade of cardiovascular and autonomic dysfunction at the time of surgery, age, comorbidity, and type of mutation. Alternative treatment modalities with drugs stabilizing the native tetrameric conformation of TTR and inhibiting fibril formation are currently being studied.

Sepsis and catecholamine support are the major risk factors for critical illness polyneuropathy after open heart surgery'

BACKGROUND

Critical illness polyneuropathy (CIP) remains a problem after open heart surgery. Recently, we reported about a retrospectively performed study pointing out that sepsis, the application of higher amounts of catecholamines and intervention such as chronic venovenous hemodiafiltration may be involved in the onset of CIP. A prospectively performed study is presented in order to evaluate the significance of risk factors initially after open heart surgery.

METHODS

From June 1997 until September 1998, patients undergoing open heart surgery and being ventilated beyond 3 days were prospectively enrolled in the study and underwent a standard protocol of electromyographic investigation in order to determine CIP. Several items were recorded: amount of catecholamines, serum levels of urea, creatinine, albumin, and glucose. The duration of sepsis and chronic venovenous hemodiafiltration were reevaluated. Additionally the age, the left ventricular end-diastolic pressure prior to the operation, the time of ICU stay and the time of ventilatory support were compared.

RESULTS

Within the observation period, 37 adult patients could be enrolled in the study, whereas 12 patients did develop CIP and 7 patients did not. Patients developing CIP required significantly different amounts of epinephrine (0.17 +/- 0.02 vs. 0.09 +/- 0.01 mg/kg/day, p < 0.05, t-test) higher amounts of norepinephrine (0.06 +/- 0.02 vs. 0.02 +/- 0.01 mg/kg/day, p<0.05, t-test), and lesser dosages of dobutamine (2.2 +/- 0.5 vs. 4.9 +/- 0.7, p<0.05, t-test). After cardiac surgery, the plasma levels of urea was initially significantly elevated in patients developing CIP (127.4 +/- 10.5 vs 97.3 +/- 18.5, p<0.05, t-test) Patients suffering from CIP stayed significantly longer in the ICU (40.3 +/- 11.7 vs. 19.6 +/- 11.3 days, p < 0.05 t-test) with an extended time of ventilator support. (769.6 +/- 05.0 vs 295.0 +/- 134.0 hours, p<0.05, t-test). Patients of the CIP group were suffering significant longer from sepsis than patients without CIP.

CONCLUSIONS

Sepsis and catecholamine support and an increased level of urea were associated with the development of CIP. The prevention of sepsis and a modulation of the catecholamine support in order to improve microcirculatory flow may reduce the onset of CIP in patients undergoing open heart surgery.

Robustness testing of a reversed-phase high-performance liquid chromatographic assay: comparison of fractional and asymmetrical factorial designs

Robustness tests were performed on a reversed-phase HPLC assay for triadimenol. Different experimental designs were compared. Two-level fractional factorial designs with different resolutions were used to study the influence of procedure-related factors. The factors chromatographic column manufacturer at four levels and instrument at three levels were stepwise included in the study using asymmetrical factorial designs. The significance of the factor effects was determined statistically, using two types of error estimates in the calculation of critical effects, and graphically, by means of half-normal plots. The asymmetrical designs turned out to be an efficient and economic method to examine the influence of factors at different numbers of levels in the robustness testing of analytical methods.

Treatment of cerebral Langerhans cell histiocytosis

Cerebral Langerhans cell histiocytosis (LCH) is a rare granulomatous disorder which may be primary or secondary or solitary or multiple. Brain structures outside the hypothalamic-pituitary axis are only scarcely involved, even in multisystem varieties. Since there are neither controlled therapeutic trials nor systematic analyses of hitherto reported cases, optimal treatment strategies are not known. To evaluate the effect of different treatment modalities, we analyzed previous reports of extrahypothalamic LCH back to 1980 in which the diagnosis was made on the basis of examination of cerebral tissues. Thirty-five histologically examined cases were identified, including 10 patients presenting with multiple cerebral lesions. Adding one own case followed up for 10 years, 16 patients had cerebral involvement secondary to multisystem LCH, while another 20 patients had primary cerebral LCH. The peak incidence was far beyond the pediatric range for both primary and secondary cerebral LCH. Localized lesions can be treated successfully by surgery or radiation following biopsy. Chemotherapy may be an additional option. Multiple lesions can tentatively be controlled by chemotherapy and, possibly, radiation. The ultimate outcome is determined by whether or not recurrencies or de-novo lesions will appear and the course of the systemic disease. Studies addressing the effects of therapy in cerebral LCH are urgently needed.

Myopathy in critically ill patients

OBJECTIVE

To review myopathic changes occurring during intensive care treatment in the light of recent information about manifestation, clinical settings, pathophysiology, and histomorphologic changes.

DATA SOURCES

The computerized MEDLINE database, bibliography of pertinent articles, and the author's personal files.

STUDY SELECTION

Studies were selected according to their relevance to myopathic complications in critically ill patients.

DATA EXTRACTION

All applicable data were extracted.

DATA SYNTHESIS

Myopathic changes occur frequently in patients treated in the intensive care unit (ICU). Three main types have been identified: critical illness myopathy, myopathy with selective loss of myosin filaments, and acute necrotizing myopathy of intensive care. These histologic types probably represent variable expressions of a toxic effect not yet identified. Candidates for such myotoxic effects are the mediators of the systemic response in sepsis and high-dose administration of corticosteroids and muscle relaxants. The influence of these latter agents appears to be particularly important in the pathogenesis of myosin loss and myonecrosis. Experimental studies suggest that axonal damage attributable to critical illness neuropathy can be an additional factor triggering myopathies in the ICU. Muscle membrane inexcitability was recently identified as an alternative mechanism of severe weakness in ICU patients.

CONCLUSIONS

Myopathic changes are surprisingly frequent in critically ill patients. The clinical importance of this finding is still unknown, but it is likely that weakness caused by myopathy prolongs ICU stay and rehabilitation. Because corticosteroids and muscle relaxants appear to trigger some types of ICU myopathy, they should be avoided or administered at the lowest doses possible. Sepsis, denervation, and muscle membrane inexcitability may be additional factors. Studies addressing the pathophysiology of myopathy in critically ill patients are urgently needed.

Evaluation of the H-point standard additions method (HPSAM) and the generalized H-point standard additions method (GHPSAM) for the UV-analysis of two-component mixtures

The H-point standard additions method (HPSAM) and two versions of the generalized H-point standard additions method (GHPSAM) are evaluated for the UV-analysis of two-component mixtures. Synthetic mixtures of anhydrous caffeine and phenazone as well as of atovaquone and proguanil hydrochloride were used. Furthermore, the method was applied to pharmaceutical formulations that contain these compounds as active drug substances. This paper shows both the difficulties that are related to the methods and the conditions by which acceptable results can be obtained.

[Critical polyneuropathy]

Contrary to earlier belief, muscle weakness and atrophy in critically ill patients is not due to inactivity or disuse but rather caused by neuromuscular disorders arising de novo during the stay in the ICU. Clinical manifestations include delayed weaning from the respirator and prolongation of the rehabilitation phase. The available data indicate that critical illness polyneuropathy is the most frequent cause of such secondary neuromuscular problems. For differential diagnosis prolonged neuromuscular blockade and several myopathies have to be taken into consideration. The pathogenesis of critical illness polyneuropathy is unknown. It has been suggested that the factors mediating the systemic inflammatory response are also responsible for axonal damage in critical illness polyneuropathy. We recently described a neurotoxic activity present in the sera of affected patients, which can be reversed completely by NMDA antagonists. The critical illness per se is unrelated to the development of neuropathy. By contrast, occurrence of myopathies may be triggered by exogenous factors such as high-dose glucosteroids and non-depolarizing muscle blocking agents. Detailed electrodiagnostic studies are desirable in patients with long-lasting ICU stays, whenever possible as weekly monitoring. In doubtful cases, muscle biopsy might be necessary for proper diagnosis and management.

[Continuous monitoring of the recurrent laryngeal nerve]

A new "all in one" sensing device for tracing and continuous intraoperative monitoring of the recurrent laryngeal nerve during thyroid surgery is described. The system, based on a double ballooned endotracheal tube, is atraumatic, easy to use and sensitive even to imminent trauma to the nerves. The most striking feature of this instrument is that it operates outside the sterile operating field and truly monitors continuously throughout the operation.

Critical illness polyneuropathy: a new iatrogenically induced syndrome after cardiac surgery?

OBJECTIVE

Critical illness polyneuropathy (CIP) is a newly described severe complication after open heart surgery leading to tetraplegia for weeks to months. The purpose of the study was to gather further information on critical illness polyneuropathy developing in patients after cardiac surgery and to evaluate the hypothetical risk factors possibly related to the onset of this neurological disorder.

METHODS

From July 1994 to October 1995, 7 out of 1511 patients undergoing open heart surgery developed critical illness polyneuropathy, which was diagnosed on the basis of electromyographic and nerve conduction features. The only common clinical finding was an intensive care unit (ICU) stay beyond seven days, therefore a similar group of 37 patients staying longer than seven days in the intensive care unit during the same period of time was evaluated and retrospectively compared to the 7 patients developing critical illness polyneuropathy. Univariate analysis of several traits was performed to evaluate possible risk factors.

RESULTS

4 Out of 7 patients in the CIP group died, all due to multiple organ failure, in contrast to 3/37 patients in the control group, again due to multiple organ failure. Patients developing CIP were staying significantly longer in the ICU (62+/-3 versus 14+/-8 days, P < 0.01) and had a significantly longer time on ventilator support (50+/-28 versus 7+/-13 days, P < 0.01) The incidence of sepsis was significantly higher in the CIP group than in the control group (85.7 versus 10.8%, P < 0.01). Compared to the control group the proportion of patients receiving corticosteroids (100 versus 10.8%, P < 0.01) and increased dosages of epinephrine and norepinephrine was higher in the CIP group (85.7 versus 35.1%, P < 0.05). Furthermore, the proportion of patients requiring chronic venovenous hemodiafiltration was significantly elevated in the CIP group (85.7 versus 5.4%, P < 0.01).

CONCLUSIONS

CIP, despite it's benign nature due to it's spontaneous remission in patients who survive, is a disturbing complication following cardiac surgery which is associated with high mortality, a prolonged stay in the ICU, as well as an extended time on ventilator support. Interventions like chronic hemodiafiltration, the application of corticosteroids and the administration of high doses of catecholamines are more frequent in patients with CIP. Whether this indicates a causal relationship remains to be elucidated.

Serum neuron-specific enolase as early predictor of outcome after cardiac arrest

OBJECTIVE

To examine the prognostic value of serum neuron-specific enolase for early prediction of outcome in patients at risk for anoxic encephalopathy after cardiac arrest.

DESIGN

Prospective study.

SETTING

Coronary intensive care unit of the University of Heidelberg.

PATIENTS

Forty-three patients (66.8 +/- 12.7 [SD] yrs, range 33 to 85) who had had either primary or secondary cardiac arrest, followed by cardiopulmonary resuscitation (CPR).

INTERVENTIONS

Serial blood samples and clinical examinations.

MEASUREMENTS AND MAIN RESULTS

Serum neuron-specific enolase concentrations were determined after CPR on 7 consecutive days. Twenty-five patients remained comatose and subsequently died; 18 patients survived the first 3 months and had no relevant functional deficit at 3-month follow-up. Neuron-specific enolase concentrations were correlated with neurologic outcome. Concentrations of >33 ng/mL predicted persistent coma with a high specificity (100%) and a positive predictive value of 100%. Overall sensitivity was 80%, with a negative predictive value of 78%. Serum concentrations of neuron-specific enolase exceeded this cutoff value no more than 3 days after cardiac arrest in 95% of patients in whom these concentrations had exceeded 33 ng/mL.

CONCLUSIONS

In patients who have been resuscitated after cardiac arrest, serum neuron-specific enolase concentrations of >33 ng/mL predict persistent coma with a high specificity. Values below this cutoff level do not necessarily indicate complete recovery, because this method has a sensitivity of 80%.

Neurocritical care for acute ischemic stroke

Treatment strategies for acute ischemic stroke include general and specific measures. The rationale for these strategies is discussed, and the current practice in the acute phase of ischemic stroke is presented. Special attention is given to the patient requiring intensive care.