Brigitte Stemper

Enzyme replacement therapy improves function of C-, Aδ-, and Aβ-nerve fibers in Fabry neuropathy

Background: Peripheral neuropathy in Fabry disease predominantly involves small nerve fibers. Recently, enzyme replacement therapy (ERT) with recombinant human α-galactosidase A has become available. Objective: To evaluate whether ERT improves Fabry neuropathy. Methods: In 22 Fabry patients (age 27.9 ± 8.0 years) undergoing ERT with recombinant human α-galactosidase A (agalsidase beta) for 18 (n = 11) or 23 (n = 11) months and in 25 control subjects (age 29.0 ± 10.4 years), the authors performed quantitative sensory testing using the 4, 2, and 1 stepping algorithm (CASE IV™). Detection thresholds of vibration (VDT) on the first toe were assessed; cold detection thresholds (CDT), heat-pain onset (HP 0.5), and intermediate heat-pain (HP 5.0) assessments were made on the dorsum of the feet. Patient values above mean + 2.5 SD of control values were considered abnormal. Results: Before ERT, VDT, CDT, HP 0.5, and HP 5.0 were higher in patients than control subjects (p < 0.05). Following ERT, patients developed lower thresholds than prior to ERT for VDT (15.5 ± 3.5 vs 14.3 ± 4.1; p < 0.05), HP 0.5 (22.3 ± 6.7 vs 19.4 ± 1.3; p < 0.01), and HP 5.0 (27.3 ± 5.6 vs 22.5 ± 2.3; p < 0.01). Moreover, fewer patients had abnormal results of VDT (2 vs 4), CDT (7 vs 12), HP 0.5 (0 vs 9), and HP 5.0 (4 vs 20) after than before ERT. Conclusions: ERT therapy with agalsidase beta significantly improves function of C-, Aδ-, and Aβ-nerve fibers and intradermal vibration receptors in Fabry neuropathy. Lack of recovery in some patients with abnormal cold or heat-pain perception suggests the need for early ERT, prior to irreversible nerve fiber loss.

Small fiber dysfunction predominates in Fabry neuropathy.

Summary Fabry disease is an X-linked recessive disease with a reduction of lysosomal &agr; galactosidase A and consecutive storage of glycolipids e.g., in the brain, kidney, skin, and nerve fibers. Cardinal neurologic findings are hypohidrosis, painful episodes, and peripheral neuropathy. So far, the neurophysiological findings regarding the extent of large and small fiber dysfunction are contradictory. This study evaluated large and small nerve fiber function in a homogeneous group of Fabry patients. In 24 of 30 Fabry patients with creatinine below 194.7 mmol/L the authors assessed median, ulnar, and peroneal motor conduction velocity (MCV) and median, ulnar, and sural sensory conduction velocity (SCV) nerve conduction to study the function of thickly myelinated nerve fibers. In addition, the authors studied sympathetic skin responses (SSR) at both hands and feet in 24 patients. To evaluate A &bgr; nerve fiber function, the authors determined vibratory detection thresholds (VDT) at the first toe in 30 patients. Function of A &dgr; and C fibers was assessed by quantitative sensory testing of cold detection threshold (CDT) and heat-pain detection thresholds (HPDT). Nerve conduction studies showed significantly decreased amplitudes of MCVs and SCVs in Fabry patients as compared to controls. However, individual results of MCV and SCV studies were only mildly impaired. SSRs were present in all tested patients but SSR amplitudes were significantly decreased in Fabry patients in comparison to controls. VDT, CDT, and HPDT were significantly elevated in Fabry patients as compared to controls. However, only six patients had pathologic VDT, 19 had increased CDT, and 25 had elevated HPDT at a high level of stimulation. In Fabry patients, small fiber dysfunction is more prominent than large fiber dysfunction, confirming previous findings of sural nerve biopsies. The results suggest a higher vulnerability of small-diameter nerve fibers than of the thickly myelinated fibers.

Intravitreal aflibercept injection for macular edema due to central retinal vein occlusion: two-year results from the COPERNICUS study.

PURPOSE To evaluate the efficacy and safety of intravitreal aflibercept injection (IAI) for the treatment of macular edema secondary to central retinal vein occlusion (CRVO). DESIGN Randomized, double-masked, phase 3 trial. PARTICIPANTS A total of 188 patients with macular edema secondary to CRVO. METHODS Patients received IAI 2 mg (IAI 2Q4) (n = 114) or sham injections (n = 74) every 4 weeks up to week 24. During weeks 24 to 52, patients from both arms were evaluated monthly and received IAI as needed, or pro re nata (PRN) (IAI 2Q4 + PRN and sham + IAI PRN). During weeks 52 to 100, patients were evaluated at least quarterly and received IAI PRN. MAIN OUTCOME MEASURES The primary efficacy end point was the proportion of patients who gained ≥ 15 letters in best-corrected visual acuity (BCVA) from baseline to week 24. This study reports week 100 results. RESULTS The proportion of patients gaining ≥ 15 letters was 56.1% versus 12.3% (P<0.001) at week 24, 55.3% versus 30.1% (P<0.001) at week 52, and 49.1% versus 23.3% (P<0.001) at week 100 in the IAI 2Q4 + PRN and sham + IAI PRN groups, respectively. The mean change from baseline BCVA was also significantly higher in the IAI 2Q4 + PRN group compared with the sham + IAI PRN group at week 24 (+17.3 vs. -4.0 letters; P<0.001), week 52 (+16.2 vs. +3.8 letters; P<0.001), and week 100 (+13.0 vs. +1.5 letters; P<0.0001). The mean reduction from baseline in central retinal thickness was 457.2 versus 144.8 μm (P<0.001) at week 24, 413.0 versus 381.8 μm at week 52 (P = 0.546), and 390.0 versus 343.3 μm at week 100 (P = 0.366) in the IAI 2Q4 + PRN and sham + IAI PRN groups, respectively. The mean number (standard deviation) of PRN injections in the IAI 2Q4 + PRN and sham + IAI PRN groups was 2.7 ± 1.7 versus 3.9 ± 2.0 during weeks 24 to 52 and 3.3 ± 2.1 versus 2.9 ± 2.0 during weeks 52 to 100, respectively. The most frequent ocular serious adverse event from baseline to week 100 was vitreous hemorrhage (0.9% vs. 6.8% in the IAI 2Q4 + PRN and sham + IAI PRN groups, respectively). CONCLUSIONS The visual and anatomic improvements after fixed dosing through week 24 and PRN dosing with monthly monitoring from weeks 24 to 52 were diminished after continued PRN dosing, with a reduced monitoring frequency from weeks 52 to 100.

QUANTITATIVE THERMAL PERCEPTION TESTING IN ADULTS

In 225 adults aged 18 to 80 years, normative warm and cold perception thresholds were assessed at the volar distal forearm, thenar eminence, lower medial calf, and lateral dorsal foot using the method of limits and a Thermotest (Somedic, Stockholm, Sweden). A 1.5-cm x 2.5-cm thermode, a 1 degrees C/s stimulus change rate, and a 32 degrees C baseline temperature were applied. Thresholds of five consecutive stimuli were averaged. At the thenar eminence a 3 degrees C/s stimulation was applied in addition to the 1 degree C/s stimulation. Effects of spatial summation were studied at the calf and forearm by additional testing with a 2.5-cm x 5.0-cm thermode. To evaluate the influence of skin temperature, thresholds were correlated with the pretest skin temperature at the tested sites. Reproducibility of stimulus perception was determined by comparing the lowest to the highest response to five consecutive stimuli. Results showed sufficient accuracy of thermal perception thresholds. Thresholds were higher with the 3 degrees C/s stimulation than with the 1 degree C/s stimulation. Thresholds were lower with the large than with the small probe. Skin temperature had only minimal influence on thresholds. The use of a 32 degrees C baseline temperature and a 1 degree C/s stimulus change rate is recommended. The large probe should be used at body sites where the entire thermode surface adjusts planely to the skin. Warming up the tested skin area is not necessary before thermotesting.

Intravitreal Aflibercept for Macular Edema Secondary to Central Retinal Vein Occlusion: 18-Month Results of the Phase 3 GALILEO Study

PURPOSE To evaluate intravitreal aflibercept for treatment of macular edema secondary to central retinal vein occlusion (CRVO). DESIGN Randomized, double-masked, phase 3 study. METHODS A total of 177 patients with macular edema secondary to CRVO were randomized to receive 2 mg intravitreal aflibercept (n = 106) or sham (n = 71) every 4 weeks for 20 weeks. From weeks 24 to 48, patients were monitored every 4 weeks; the former group received intravitreal aflibercept as needed (PRN), and the sham group received sham. From weeks 52 to 76, patients were monitored every 8 weeks, and both groups received intravitreal aflibercept PRN. The primary endpoint (proportion of patients who gained ≥15 letters) was at week 24. This study reports exploratory outcomes at week 76. RESULTS The proportion of patients who gained ≥15 letters in the intravitreal aflibercept and sham groups was 60.2% vs 22.1% at week 24 (patients discontinued before week 24 were considered nonresponders; P < .0001), 60.2% vs 32.4% at week 52 (last observation carried forward, P < .001), and 57.3% vs 29.4% at week 76 (last observation carried forward; P < .001). Mean μm change from baseline central retinal thickness was -448.6 vs -169.3 at week 24 (P < .0001), -423.5 vs -219.3 at week 52 (P < .0001), and -389.4 vs -306.4 at week 76 (P = .1122). Over 76 weeks, the most common ocular serious adverse event in the intravitreal aflibercept group was macular edema (3.8%). CONCLUSIONS The visual and anatomic improvements seen after fixed, monthly dosing at week 24 were largely maintained when treatment intervals were extended. Patients with macular edema following CRVO benefited from early treatment with intravitreal aflibercept.

Reduced cerebral blood flow velocity and impaired cerebral autoregulation in patients with Fabry disease

Abstract.In Fabry disease, there is glycosphingolipid storage in vascular endothelial and smooth muscle cells and neurons of the autonomic nervous system. Vascular or autonomic dysfunction is likely to compromise cerebral blood flow velocities and cerebral autoregulation. This study was performed to evaluate cerebral blood flow velocities and cerebral autoregulation in Fabry patients. In 22 Fabry patients and 24 controls, we monitored resting respiratory frequency, electrocardiographic RR-intervals, blood pressure, and cerebral blood flow velocities (CBFV) in the middle cerebral artery using transcranial Doppler sonography. We assessed the Resistance Index, Pulsatility Index, Cerebrovascular Resistance, and spectral powers of oscillations in RR-intervals, mean blood pressure and mean CBFV in the high (0.15–0.5 Hz) and sympathetically mediated low frequency (0.04–0.15 Hz) ranges using autoregressive analysis. Cerebral autoregulation was determined from the transfer function gain between the low frequency oscillations in mean blood pressure and mean CBFV. Mean CBFV (P < 0.05) and the powers of mean blood pressure (P < 0.01) and mean CBFV oscillations (P < 0.05) in the low frequency range were lower,while RR-intervals, Resistance Index (P < 0.01), Pulsatility Index, Cerebrovascular Resistance (P < 0.05), and the transfer function gain between low frequency oscillations in mean blood pressure and mean CBFV (P < 0.01) were higher in patients than in controls. Mean blood pressure, respiratory frequency and spectral powers of RR-intervals did not differ between the two groups (P > 0.05). The decrease of CBFV might result from downstream stenoses of resistance vessels and dilatation of the insonated segment of the middle cerebral artery due to reduced sympathetic tone and vessel wall pathology with decreased elasticity. The augmented gain between blood pressure and CBFV oscillations indicates inability to dampen blood pressure fluctuations by cerebral autoregulation. Both, reduced CBFV and impaired cerebral autoregulation, are likely to be involved in the increased risk of stroke in patients with Fabry disease.

Lower limb cold exposure induces pain and prolonged small fiber dysfunction in Fabry patients.

Abstract In Fabry disease, an X‐linked &agr;‐galactosidase A deficiency, painful crises and limb paresthesias are possibly linked to thermal exposure. Small nerve fiber function has not yet been tested after cold challenge. In two Fabry patients (15 and 17 years old), their heterozygote mother, their healthy sister, and eight controls, we determined warm and cold perception thresholds at the dorsal foot and the lower medial calf (method of limits, Somedic‐Thermotest™), before and 1, 5, 10 and 15 min after 30 s immersion of one leg into 5°C water. Discomfort was rated from 0 to 10. At baseline, thermal thresholds of all participants were normal. In contrast to controls, the patients tolerated 30 s cold stimulation only with interruptions. The mother aborted stimulation after 6 s because of pain. The patients and their mother reported intense burning pain and numbness during and after stimulation. After cold exposure, thermal sensation was highly abnormal for 20 min in one and 80 min in the other brother. In controls, thermal thresholds were somewhat elevated after stimulation but normalized within 10.0±4.6 min. Discomfort during cold exposure was rated 8–10 by the patients and their mother, but 3–5 by the healthy persons. We assume that glycolipid accumulation in cutaneous and vasa nervorum vessels as well as small nerve axons accounts for skin and small fiber malperfusion during cold induced vasoconstriction. Transitory ischemia initiated burning pain and prolonged small fiber dysfunction.

Long-term impact of interferon beta-1b in patients with CIS: 8-year follow-up of BENEFIT

Objective To examine the long-term impact of early treatment initiation of interferon beta-1b (IFNB1b, Betaferon/Betaseron) in patients with a first event suggestive of multiple sclerosis (MS). Methods In the original placebo-controlled phase of BENEFIT, patients were randomised to IFNB1b 250 μg or placebo subcutaneously every other day. After 2 years or diagnosis of clinically definite MS (CDMS), all patients were offered open-label IFNB1b treatment for a maximum duration of 5 years. Thereafter, patients were enrolled in an observational extension study for up to 8.7 years. Results Of the initial 468 patients, 284 (60.7%; IFNB1b: 178 (61.0% of the original arm), placebo: 106 (60.2% of original arm)) were enrolled in the extension study. 94.2% of patients were receiving IFNB1b. Patients originally randomised to IFNB1b had a reduced risk of developing CDMS by 32.2% over the 8-year observation period (HR 0.678; 95% CI 0.525 to 0.875; p=0.0030), a longer median time to CDMS by 1345 days (95% CI 389 to 2301), and a lower annualised relapse rate (0.196 (95% CI 0.176 to 0.218) versus 0.255 (95% CI 0.226 to 0.287), p=0.0012), with differences mainly emerging in the first year of the study. Cognitive outcomes remained higher in the early treated patients. EDSS remained low over time with a median of 1.5 in both arms. Conclusions These 8-year results provide further evidence supporting early initiation of treatment with IFNB1b in patients with a first event suggestive of MS.

Deep brain stimulation improves orthostatic regulation of patients with Parkinson disease

Objective: To evaluate whether subthalamic nucleus (STN) stimulation has an effect on the orthostatic regulation of patients with Parkinson disease (PD), we studied cardiovascular regulation during on and off phases of STN stimulation. Methods: We examined 14 patients with PD (mean age 58.1 ± 5.8 years, 4 women, 10 men) with bilateral STN stimulators. Patients underwent 3 minutes of head-up tilt (HUT) testing during STN stimulation and after 90 minutes interruption of stimulation. We monitored arterial blood pressure (BP), RR intervals (RRI), respiration, and skin blood flow (SBF). Baroreflex sensitivity (BRS) was assessed as the square root of the ratio of low-frequency power of RRI to the low-frequency power of systolic BP for coherences above 0.5. Results: During the on phase of the STN stimulation, HUT induced no BP decrease, a significant tachycardia, and a significant decrease of SBF. During the off phase of stimulation, HUT resulted in significant decreases in BPsys and RRI and only a slight SBF decrease. HUT induced no change of BRS during stimulation, but lowered BRS when the stimulator was off (p < 0.05). Conclusions: STN stimulation of patients with PD increases peripheral vasoconstriction and BRS and stabilizes BP, thereby improving postural hypotension in patients with PD. The results indicate that STN stimulation not only alleviates motor deficits but also influences autonomic regulation in patients with PD.

Effects of interferon beta-1b on cognitive performance in patients with a first event suggestive of multiple sclerosis

Background: Cognitive dysfunction occurs at the earliest stages of multiple sclerosis (MS), including the stage of clinically isolated syndrome (CIS). Methods: We evaluated the impact of interferon beta-1b (IFNβ-1b) 250 µg on cognitive performance during the CIS stage in the BENEFITstudy. Cognition was assessed by Paced Auditory Serial Addition Test-3” (PASAT-3”) scores. Results: Improvement in PASAT-3” score from baseline to year two was greater for IFNβ-1b treatment than placebo in patients not reaching clinically definite MS (CDMS) by year two. The treatment effect was maintained at year five and was statistically significant. Conclusions: To conclude, early IFNβ-1b treatment had a sustained positive effect on PASAT-3” score over the 5-year BENEFIT study.