Ingela Nilsson Remahl

Familial insensitivity to pain (HSAN V) and a mutation in the NGFB gene. A neurophysiological and pathological study.

We have studied a large Swedish family with a mutation in the nerve growth factor beta (NGFB) gene causing insensitivity to deep pain without anhidrosis (hereditary sensory and autonomic neuropathy, type V; HSAN V). Painfree joint destruction and fractures were common. Peripheral nerve conduction was normal, but temperature thresholds were increased. Sural nerve biopsies showed a moderate loss of Aδ fibers and a severe reduction of C fibers. The three most severely affected cases were all born to consanguineous parents, and were homozygotes for the causal genetic mutation. Treatment of these patients is discussed. Muscle Nerve, 2004

Fluconazole-induced intoxication with phenytoin in a patient with ultra-high activity of CYP2C9

PurposeThe cytochrome P450 enzyme CYP2C9 metabolizes several important drugs, such as warfarin and oral antidiabetic drugs. The enzyme is polymorphic, and all known alleles, for example, CYP2C9*2 and*3, give decreased activity. Ultra-high activity of the enzyme has not yet been reported.MethodsWe present a patient with Behçet’s disease who required treatment with high doses of phenytoin. When fluconazole, a potent inhibitor of CYP2C9, was added to the treatment regimen, the patient developed ataxia, tremor, fatigue, slurred speech and somnolence, indicating phenytoin intoxication. On suspicion of ultra-high activity of CYP2C9, a phenotyping test for CYP2C9 with losartan was performed.ResultsThe patient was shown to have a higher activity of CYP2C9 than any of the 190 healthy Swedish Caucasians used as controls.ConclusionsOur finding of an ultrarapid metabolism of losartan and phenytoin may apply to other CYP2C9 substrates, where inhibition of CYP2C9 may cause severe adverse drug reactions.

Utilization and safety of onabotulinumtoxinA for the prophylactic treatment of chronic migraine from an observational study in Europe

Objective To examine treatment utilization patterns and safety of onabotulinumtoxinA for the prophylactic treatment of chronic migraine in routine clinical practice. Background Clinical trials support onabotulinumtoxinA for the prophylaxis of headache in patients with chronic migraine, but real-world data are limited. Design/methods A prospective, observational, post-authorization study in adult patients with chronic migraine treated with onabotulinumtoxinA. Data were collected at the first study injection and approximately every three months for ≤52 weeks for utilization and ≤64 weeks for safety data, and summarized using descriptive statistics. Results Eighty-five physicians (81% neurologists) at 58 practices in the United Kingdom, Germany, Spain, and Sweden participated and recruited 1160 patients (84.2% female, median age 46.6 years). At baseline, 85.8% of patients had physician diagnoses of chronic migraine/transformed migraine and reported an average of 11.3 (SD = 6.9) severe headache days per 28 days; 50.6% had previously used onabotulinumtoxinA for chronic migraine. A total of 4017 study treatments were observed. The median number of injection sites (n = 31) and total dose (155 U) were consistent across all treatment sessions, with a median 13.7 weeks observed between sessions. At least one treatment-related adverse event was reported by 291 patients (25.1%); the most frequently reported treatment-related adverse event was neck pain (4.4%). Most patients (74.4%) were satisfied/extremely satisfied with onabotulinumtoxinA treatment. Conclusions Patient demographics/characteristics are consistent with published data on the chronic migraine population. Utilization of onabotulinumtoxinA treatment for chronic migraine appears to be consistent with the Summary of Product Characteristics and published PREEMPT injection paradigm. No new safety signals were identified.

Observations at the CNS-PNS border of ventral roots connected to a neuroma

Previous studies have shown that numerous sprouts originating from a neuroma, after nerve injury in neonatal animals, can invade spinal nerve roots. However, no study with a focus on how such sprouts behave when they reach the border between the central and peripheral nervous system (CNS–PNS border) has been published. In this study we have in detail examined the CNS–PNS border of ventral roots in kittens with light and electron microscopy after early postnatal sciatic nerve resection. A transient ingrowth of substance P positive axons was observed into the CNS, but no spouts remained 6 weeks after the injury. Using serial sections and electron microscopy it was possible to identify small bundles of unmyelinated axons that penetrated from the root fascicles for a short distance into the CNS. These axons ended blindly, sometimes with a growth cone-like terminal swelling filled with vesicles. The axon bundles were accompanied by p75 positive cells in both the root fascicles and the pia mater, but not in the CNS. It may thus be suggested that neurotrophin presenting p75 positive cells could facilitate axonal growth into the pia mater and that the lack of such cells in the CNS compartment might contribute to the failure of growth into the CNS. A maldevelopment of myelin sheaths at the CNS–PNS border of motor axons was observed and it seems possible that this could have consequences for the propagation of action potential across this region after neonatal nerve injury. Thus, in this first detailed study on the behavior of recurrent sprouts at the CNS–PNS border.