Comparative analysis of the scope of European Union paediatric investigation plans with corresponding orphan designations

BACKGROUND

Market forces may not be sufficient to stimulate research and development of medicines for small patient populations, such as children and patients with rare diseases. Both the European Union Orphan and Paediatric Regulations were introduced to address the unmet public health needs of these smaller patient populations through the use of incentives, rewards and obligations. Developers for new medicines for rare diseases must agree a paediatric investigation plan (PIP) or waiver with the European Medicines Agency's (EMA) Paediatric Committee (PDCO), and can also apply for an orphan designation (OD) from the EMA's Committee of Orphan Medicinal Products (COMP). The scope of both the OD and the PIP (or waiver) is defined by the agreed condition.

OBJECTIVES

The aim of this study was to analyse the approach of PDCO and COMP in defining the appropriate condition for a PIP or OD, respectively, in order to investigate potential challenges in the paediatric development of orphan medicines which have to meet the requirements of both legislations.

METHODS

A comparative analysis of PIP conditions and OD conditions was performed for medicines that have been reviewed by both Committees.

RESULTS

We found that in the substantial majority of cases there is no divergence between the conclusions of COMP and PDCO with regard to the condition for which a medicine is to be developed.

CONCLUSION

These findings demonstrate that a collaborative approach allows both Regulations to work synergistically to foster pharmaceutical development for rare diseases in childhood.

Balancing drug resistance and growth rates via compensatory mutations in the Plasmodium falciparum chloroquine resistance transporter

The widespread use of chloroquine to treat Plasmodium falciparum infections has resulted in the selection and dissemination of variant haplotypes of the primary resistance determinant PfCRT. These haplotypes have encountered drug pressure and within-host competition with wild-type drug-sensitive parasites. To examine these selective forces in vitro, we genetically engineered P. falciparum to express geographically diverse PfCRT haplotypes. Variant alleles from the Philippines (PH1 and PH2, which differ solely by the C72S mutation) both conferred a moderate gain of chloroquine resistance and a reduction in growth rates in vitro. Of the two, PH2 showed higher IC50 values, contrasting with reduced growth. Furthermore, a highly mutated pfcrt allele from Cambodia (Cam734) conferred moderate chloroquine resistance and enhanced growth rates, when tested against wild-type pfcrt in co-culture competition assays. These three alleles mediated cross-resistance to amodiaquine, an antimalarial drug widely used in Africa. Each allele, along with the globally prevalent Dd2 and 7G8 alleles, rendered parasites more susceptible to lumefantrine, the partner drug used in the leading first-line artemisinin-based combination therapy. These data reveal ongoing region-specific evolution of PfCRT that impacts drug susceptibility and relative fitness in settings of mixed infections, and raise important considerations about optimal agents to treat chloroquine-resistant malaria.

Proteomic analysis of the Plasmodium male gamete reveals the key role for glycolysis in flagellar motility

Background

Gametogenesis and fertilization play crucial roles in malaria transmission. While male gametes are thought to be amongst the simplest eukaryotic cells and are proven targets of transmission blocking immunity, little is known about their molecular organization. For example, the pathway of energy metabolism that power motility, a feature that facilitates gamete encounter and fertilization, is unknown.

Methods

Plasmodium berghei microgametes were purified and analysed by whole-cell proteomic analysis for the first time. Data are available via ProteomeXchange with identifier PXD001163.

Results

615 proteins were recovered, they included all male gamete proteins described thus far. Amongst them were the 11 enzymes of the glycolytic pathway. The hexose transporter was localized to the gamete plasma membrane and it was shown that microgamete motility can be suppressed effectively by inhibitors of this transporter and of the glycolytic pathway.

Conclusions

This study describes the first whole-cell proteomic analysis of the malaria male gamete. It identifies glycolysis as the likely exclusive source of energy for flagellar beat, and provides new insights in original features of Plasmodium flagellar organization.

Electronic supplementary material

The online version of this article (doi:10.1186/1475-2875-13-315) contains supplementary material, which is available to authorized users.

Tricks in Plasmodium's molecular repertoire--escaping 3'UTR excision-based conditional silencing of the chloroquine resistance transporter gene

In the human malaria parasite Plasmodium falciparum, the major determinant of chloroquine resistance, P. falciparum chloroquine resistance transporter (pfcrt), likely plays an essential role in asexual blood stages, thus precluding conventional gene targeting approaches. We attempted to conditionally silence the expression of its ortholog in Plasmodium berghei (pbcrt) through Flp recombinase-mediated excision of the 3'untranslated region (UTR) during mosquito passage. However, parasites maintained pbcrt expression despite 3'UTR excision. Characterisation of these pbcrt mRNAs, by 3'rapid amplification of cDNA ends, identified several replacement 3'UTR sequences. Our observations demonstrate the astounding genetic plasticity of this parasite when faced with the loss of an essential gene.

Evidence that mutant PfCRT facilitates the transmission to mosquitoes of chloroquine-treated Plasmodium gametocytes

Resistance of the human malarial parasite Plasmodium falciparum to the antimalarial drug chloroquine has rapidly spread from several independent origins and is now widely prevalent throughout the majority of malaria-endemic areas. Field studies have suggested that chloroquine-resistant strains might be more infective to mosquito vectors. To test the hypothesis that the primary chloroquine resistance determinant, mutations in PfCRT, facilitates parasite transmission under drug pressure, we have introduced a mutant or wild-type pfcrt allele into the rodent model malarial parasite Plasmodium berghei. Our results show that mutant PfCRT from the chloroquine-resistant 7G8 strain has no effect on asexual blood stage chloroquine susceptibility in vivo or ex vivo but confers a significant selective advantage in competitive mosquito infections in the presence of this drug, by protecting immature gametocytes from its lethal action. Enhanced infectivity to mosquitoes may have been a key factor driving the worldwide spread of mutant pfcrt.

How can we identify parasite genes that underlie antimalarial drug resistance?

This article outlines genome-scale approaches that can be used to identify mutations in malaria (Plasmodium) parasites that underlie drug resistance and contribute to treatment failure. These approaches include genetic mapping by linkage or genome-wide association studies, drug selection and characterization of resistant mutants, and the identification of genome regions under strong recent selection. While these genomic approaches can identify candidate resistance loci, genetic manipulation is needed to demonstrate causality. We therefore also describe the growing arsenal of available transfection approaches for direct incrimination of mutations suspected to play a role in resistance. Our intention is both to review past progress and highlight promising approaches for future investigations.

Microbial translocation in simian immunodeficiency virus (SIV)-infected rhesus monkeys (Macaca mulatta)

BACKGROUND

Chronic immune activation is a hallmark of HIV infection and has been postulated as major factor in the pathogenesis of AIDS. Recent evidence suggests that activation of immune cells is triggered by microbial translocation through the impaired gastrointestinal barrier.

METHODS

To determine the association between microbial translocation and disease progression, we have retrospectively analyzed microbial products, viral load and markers of immune activation in a cohort of 37 simian immunodeficiency virus-infected rhesus monkeys, divided in two groups with distinct disease courses.

RESULTS

As seen in HIV-infected patients, we found elevated levels of lipopolysaccharide (LPS) in infected animals. However, LPS levels or LPS control mechanisms like endotoxin core antibodies or LPS-binding protein did not differ between groups with different disease progression. In contrast, neopterin, a metabolic product of activated macrophages, was higher in fast progressors than in slow progressors.

CONCLUSION

Our data indicate that translocation of microbial products is not the major driving force of immune activation in HIV infection.

Paternal effect of the nuclear formin-like protein MISFIT on Plasmodium development in the mosquito vector

Malaria parasites must undergo sexual and sporogonic development in mosquitoes before they can infect their vertebrate hosts. We report the discovery and characterization of MISFIT, the first protein with paternal effect on the development of the rodent malaria parasite Plasmodium berghei in Anopheles mosquitoes. MISFIT is expressed in male gametocytes and localizes to the nuclei of male gametocytes, zygotes and ookinetes. Gene disruption results in mutant ookinetes with reduced genome content, microneme defects and altered transcriptional profiles of putative cell cycle regulators, which yet successfully invade the mosquito midgut. However, developmental arrest ensues during the ookinete transformation to oocysts leading to malaria transmission blockade. Genetic crosses between misfit mutant parasites and parasites that are either male or female gamete deficient reveal a strict requirement for a male misfit allele. MISFIT belongs to the family of formin-like proteins, which are known regulators of the dynamic remodeling of actin and microtubule networks. Our data identify the ookinete-to-oocyst transition as a critical cell cycle checkpoint in Plasmodium development and lead us to hypothesize that MISFIT may be a regulator of cell cycle progression. This study offers a new perspective for understanding the male contribution to malaria parasite development in the mosquito vector.

The unicellular protozoan parasites that cause malaria must undergo sexual development and subsequent proliferation in mosquitoes before they can infect humans and cause malaria. We characterized the first protein with paternal effect on the development of malaria parasites in the mosquito. This protein, which we named MISFIT, is produced in the progenitor cells of male gametes and found in the nuclei of these cells as well as in the nuclei of zygotes and their invasive forms, termed ookinetes. Disruption of the gene that encodes MISFIT leads to ookinetes with reduced DNA content, a defective secretory machinery and altered expression of various regulators of DNA replication and cell division. These mutant parasites stop developing immediately after traversing the mosquito gut, leading to malaria transmission blockage. Our study offers a new perspective for understanding the sexual development of malaria parasites in the mosquito vector, which leads to transmission of one of the most devastating diseases of mankind.

The dark and the bright side of Stat3: proto-oncogene and tumor-suppressor

Stat transcription factors have been implicated in tumorigenesis in mice and men. Stat3 and Stat5 are considered powerful proto-oncogenes, whereas Stat1 has been demonstrated to suppress tumor formation. We demonstrate here for the first time that a constitutive active version of Stat3alpha (Stat3alphaC) may also suppress transformation. Mouse embryonic fibroblasts (MEFs) deficient for p53 can be transformed with either c-myc or with rasV12 alone. Interestingly, transformation by c-myc is efficiently suppressed by co-expression of Stat3alphaC, but Stat3alphaC does not interfere with transformation by the rasV12-oncogene. In contrast, transplantation of bone marrow cells expressing Stat3alphaC induces the formation of a highly aggressive T cell leukemia in mice. The leukemic cells invaded multiple organs including lung, heart, salivary glands, liver and kidney. Interestingly, transplanted mice developed a similar leukemia when the bone marrow cells were transduced with Stat3beta, which is also constitutively active when expressed at significant levels. Our experiments demonstrate that Stat3 has both - tumor suppressing and tumor promoting properties.

Reverse genetics screen identifies six proteins important for malaria development in the mosquito

Transmission from the vertebrate host to the mosquito vector represents a major population bottleneck in the malaria life cycle that can successfully be targeted by intervention strategies. However, to date only about 25 parasite proteins expressed during this critical phase have been functionally analysed by gene disruption. We describe the first systematic, larger scale generation and phenotypic analysis of Plasmodium berghei knockout (KO) lines, characterizing 20 genes encoding putatively secreted proteins expressed by the ookinete, the parasite stage responsible for invasion of the mosquito midgut. Of 12 KO lines that were generated, six showed significant reductions in parasite numbers during development in the mosquito, resulting in a block in transmission of five KOs. While expression data, time point of essential function and mutant phenotype correlate well in three KOs defective in midgut invasion, in three KOs that fail at sporulation, maternal inheritance of the mutant phenotype suggests that essential function occurs during ookinete formation and thus precedes morphological abnormalities by several days.

Female inheritance of malarial lap genes is essential for mosquito transmission

Members of the LCCL/lectin adhesive-like protein (LAP) family, a family of six putative secreted proteins with predicted adhesive extracellular domains, have all been detected in the sexual and sporogonic stages of Plasmodium and have previously been predicted to play a role in parasite–mosquito interactions and/or immunomodulation. In this study we have investigated the function of PbLAP1, 2, 4, and 6. Through phenotypic analysis of Plasmodium berghei loss-of-function mutants, we have demonstrated that PbLAP2, 4, and 6, as previously shown for PbLAP1, are critical for oocyst maturation and sporozoite formation, and essential for transmission from mosquitoes to mice. Sporozoite formation was rescued by a genetic cross with wild-type parasites, which results in the production of heterokaryotic polyploid ookinetes and oocysts, and ultimately infective Δpblap sporozoites, but not if the individual Δpblap parasite lines were crossed amongst each other. Genetic crosses with female-deficient (Δpbs47) and male-deficient (Δpbs48/45) parasites show that the lethal phenotype is only rescued when the wild-type pblap gene is inherited from a female gametocyte, thus explaining the failure to rescue in the crosses between different Δpblap parasite lines. We conclude that the functions of PbLAPs1, 2, 4, and 6 are critical prior to the expression of the male-derived gene after microgametogenesis, fertilization, and meiosis, possibly in the gametocyte-to-ookinete period of differentiation. The phenotypes detectable by cytological methods in the oocyst some 10 d after the critical period of activity suggests key roles of the LAPs or LAP-dependent processes in the regulation of the cell cycle, possibly in the regulation of cytoplasm-to-nuclear ratio, and, importantly, in the events of cytokinesis at sporozoite formation. This phenotype is not seen in the other dividing forms of the mutant parasite lines in the liver and blood stages.

Malaria parasites are transmitted between human hosts by female mosquitoes. Following fertilization between male and female gametes in the blood meal, zygotes develop into motile ookinetes that, 24 hours later, cross the mosquito midgut epithelium and encyst on the midgut wall. During this development, parasite numbers fall dramatically and as such, this may be an ideal point at which to disrupt transmission, but first essential parasite targets need to be identified. A protein family implicated in the interactions between parasites and mosquitoes is the LCCL/lectin adhesive-like protein (LAP) family. LAPs are highly expressed in the sexual and ookinete stages, yet when we removed genes encoding each of four LAPs from the genome of a rodent model malaria parasite, a developmental defect was only observed in the oocyst some ten days after the protein was first expressed. These “knockout” parasites did not undergo normal replication and consequently could not be transmitted to mice. Through genetic crosses with parasite mutants producing exclusively either female or male gametes, we demonstrate that parasites can only complete their development successfully if a wild-type lap gene is inherited through the female cell. These data throw new light on the regulation of parasite development in the mosquito, suggesting that initial development is maternally controlled, and that the LAPs may be candidates for intervention.

Camelpox virus encodes a schlafen-like protein that affects orthopoxvirus virulence

Camelpox virus (CMLV) gene 176R encodes a protein with sequence similarity to murine schlafen (m-slfn) proteins. In vivo, short and long members of the m-slfn family inhibited T-cell development, whereas in vitro, only short m-slfns caused arrest of fibroblast growth. CMLV 176 protein (v-slfn) is most closely related to short m-slfns; however, when expressed stably in mammalian cells, v-slfn did not inhibit cell growth. v-slfn is a predominantly cytoplasmic 57 kDa protein that is expressed throughout infection. Several other orthopoxviruses encode v-slfn proteins, but the v-slfn gene is fragmented in all sequenced variola virus and vaccinia virus (VACV) strains. Consistent with this, all 16 VACV strains tested do not express a v-slfn detected by polyclonal serum raised against the CMLV protein. In the absence of a small animal model to study CMLV pathogenesis, the contribution of CMLV v-slfn to orthopoxvirus virulence was studied via its expression in an attenuated strain of VACV. Recombinant viruses expressing wild-type v-slfn or v-slfn tagged at its C terminus with a haemagglutinin (HA) epitope were less virulent than control viruses. However, a virus expressing v-slfn tagged with the HA epitope at its N terminus had similar virulence to controls, implying that the N terminus has an important function. A greater recruitment of lymphocytes into infected lung tissue was observed in the presence of wild-type v-slfn but, interestingly, these cells were less activated. Thus, v-slfn is an orthopoxvirus virulence factor that affects the host immune response to infection.

Plasmodium berghei calcium-dependent protein kinase 3 is required for ookinete gliding motility and mosquito midgut invasion

Apicomplexan parasites critically depend on a unique form of gliding motility to colonize their hosts and to invade cells. Gliding requires different stage and species-specific transmembrane adhesins, which interact with an intracellular motor complex shared across parasite stages and species. How gliding is regulated by extracellular factors and intracellular signalling mechanisms is largely unknown, but current evidence suggests an important role for cytosolic calcium as a second messenger. Studying a Plasmodium berghei gene deletion mutant, we here provide evidence that a calcium-dependent protein kinase, CDPK3, has an important function in regulating motility of the ookinete in the mosquito midgut. We show that a cdpk3^– parasite clone produces morphologically normal ookinetes, which fail to engage the midgut epithelium, due to a marked reduction in their ability to glide productively, resulting in marked reduction in malaria transmission to the mosquito. The mutant was successfully complemented with an episomally maintained cdpk3 gene, restoring mosquito transmission to wild-type level. cdpk3^– ookinetes maintain their full genetic differentiation potential when microinjected into the mosquito haemocoel and cdpk3^– sporozoites produced in this way are motile and infectious, suggesting an ookinete-limited essential function for CDPK3.

The demonstration of progesterone, but not of estrogen, receptors in the developing human placenta

Since presence of steroid receptors in the human placenta has been the subject of dispute, we have investigated the existence of estrogen (ER) and progesterone (PR) receptors in trophoblasts across gestational age by a variety of different techniques. Fresh human placental tissue of trimesters 1 to 3 was paraffin-embedded or snap-frozen (-80 degrees C) and sliced (5 microns). Other tissue fragments from identical placentae were dispersed and incubated in monolayer cultures for up to 5 days. Immunocytochemistry (ICC) was performed for ER and PR in both trophoblast cells in culture and in whole tissue slices, using the sandwich antibody technique with subsequent horse-radish peroxidase reaction for colorization. In addition, long-term perifusion studies were conducted with explants of term placentae, using perifusion medium with estradiol (E, 2 ng/ml) and/or progesterone (P, 200 ng/ml). Perifused explants were then subjected to further ICC staining. Furthermore, RT-PCR for both ER and PR mRNA was performed for detection of the gene products in placentae of different gestational ages. Lastly, binding studies with iodine or tritium-labeled E and P were conducted on cytosol fractions. In placental sections and cultured trophoblasts, PR was clearly demonstrable in all placentae across different gestational ages. Abundant PR signal was found adjacent to the nuclei, and additionally in the dendrite-like pseudopods of syncytiotrophoblast cells. In contrast, no such staining signal was detected for the ER; this finding applied under all conditions investigated and at all gestational ages. Again, no staining for ER by ICC was detected in any tissue after perifusion with sex steroids. RT-PCR revealed no product for ER, but only for PR, in placentae across all gestational ages. Binding studies with labeled E and P showed no binding for either compound. Taken together, these observations suggest the presence of PR, but not of ER, in human placenta throughout gestation. Our failure to detect the ER does not entirely preclude the presence of this receptor in human trophoblasts, but might be attributed to a relatively low number and density of ER on these cells. Alternatively, estrogen's action on the placenta may be mediated by a different type of ER, such as by a non-classical membrane-bound receptor.

Relaxin triggers calcium transients in human granulosa-lutein cells

Although the peptide hormone relaxin is synthesized by the human corpus luteum in vivo, its potential to serve as a local factor in the regulation of luteal function is not clear. Using an enzyme-linked immunosorbent assay for human relaxin, we detected relaxin in the culture medium of human granulosa-lutein cells as early as after 6 days in culture. Moreover, 1 x 10(5) IU/l human chorionic gonadotropin stimulated relaxin release about fourfold during a 48-h incubation on culture days 6-8 (and 7-9), but not earlier (on days 1, 3 and 4). The stimulatory action of human chorionic gonadotropin on progesterone release was not influenced by relaxin, and relaxin alone was without stimulatory effect. However, human recombinant relaxin (between 0.1 and 12.5 micrograms/l) increased intracellular free Ca2+ basal levels to maximal peak levels exceeding 1000 nmol/l in about 64% of all tested cells (N = 168) with no obvious dependency on the culture day. The relaxin-induced Ca2+ signal was not affected by removal of extracellular Ca2+. As depletion of intracellular Ca2+ stores by ionomycin rendered the cells unresponsive to relaxin or diminished their ability to respond, these results point to an intracellular source of the Ca2+ signal. In summary, our data indicate the presence of a functional relaxin receptor on human granulosa-lutein cells, which is linked to Ca2+ release from intracellular stores.

Measles virus-specific dsRNAs are targets for unwinding/modifying activity in neural cells in vitro

Biased hypermutation events found predominantly in the matrix gene of measles virus isolated from persistent human CNS infections have been attributed to the action of a cellular unwinding/modifying activity (UMA). To define the level and distribution of this activity in brain cells, fractionated extracts were prepared from the nuclei and cytoplasm of human glioblastoma (D-54, U-251) and neuroblastoma (IMR-32, SKN-MC) cells and analyzed for their ability to modify synthetic dsRNAs specific for the measles virus (MV) matrix (M) gene. On a quantitative basis we could show that the activity localized to both the nuclear and cytoplasmic compartments of both cell types analyzed independent of cell proliferation. The presence of significant levels of UMA in the cytoplasm of human brain cells following growth arrestment in vitro with retinoic acid supports the interpretation that UMA may contribute to the attenuation of MV gene functions during the primary infection of brain cells, thereby supporting the establishment of virus persistence.

Synaptobrevin cleavage by the tetanus toxin light chain is linked to the inhibition of exocytosis in chromaffin cells

Exocytosis of secretory granules by adrenal chromaffin cells is blocked by the tetanus toxin light chain in a zinc specific manner. Here we show that cellular synaptobrevin is almost completely degraded by the tetanus toxin light chain within 15 min. We used highly purified adrenal secretory granules to show that synaptobrevin, which can be cleaved by the tetanus toxin light chain, is localized in the vesicular membrane. Proteolysis of synaptobrevin in cells and in secretory granules is reversibly inhibited by the zinc chelating agent dipicolinic acid. Moreover, cleavage of synaptobrevin present in secretory granules by the tetanus toxin light chain is blocked by the zinc peptidase inhibitor captopril and by synaptobrevin derived peptides. Our data indicate that the tetanus toxin light chain acts as a zinc dependent protease that cleaves synaptobrevin of secretory granules, an essential component of the exocytosis machinery in adrenal chromaffin cells.

Purification and properties of N5-methyltetrahydromethanopterin:coenzyme M methyltransferase from Methanobacterium thermoautotrophicum

N5-Methyltetrahydromethanopterin:coenzyme M meth-yltransferase is an integral membrane protein found in methanogenic archaea. It catalyzes an energy-conserving step in methane formation from CO2 and from acetate. The enzyme from Methanobacterium thermoautotrophicum (strain Marburg) has been purified 30-fold to apparent homogeneity. The purified enzyme had an apparent molecular mass of 670 kDa and was composed of seven different polypeptides of 34 kDa, 28 kDa, 24 kDa, 23 kDa, 21 kDa, 13 kDa, and 12 kDa. The N-terminal amino acid sequences of these polypeptides were determined. The native 670-kDa enzyme was found to contain 7.6 mol 5-hydroxybenzimidazolyl cobamide/mol, 37 mol non-heme iron/mol and 34 mol acid-labile sulfur/mol. Cobalt analyses after sodium dodecyl sulfate/polyacrylamide gel electrophoresis revealed that the corrinoid was bound to the 23-kDa polypeptide. The apparent molecular masses of the polypeptides given above were determined by sodium dodecyl sulfate/polyacrylamide gel electrophoresis without boiling the samples prior to analysis. When the samples were boiled, as is usually done, the 23-kDa polypeptide changed its apparent molecular mass to 33 kDa and the 21-kDa, 24-kDa, and 28-kDa polypeptides formed aggregates. The specific activity (apparent Vmax) of the purified methyltransferase preparation was 11.6 mumol.min-1.mg protein-1. The apparent Km for N5-methyltetrahydromethanopterin was 260 microM and that for coenzyme M was 60 microM. The preparation was absolutely dependent on the presence of Ti(III) for activity. ATP enhanced the activity 1.5-2-fold.

Norepinephrine in reflex sympathetic dystrophy: an hypothesis

Reflex sympathetic dystrophy (RSD) usually occurs in an individual who has been experiencing significant personal stress, a state associated with increased discharge of norepinephrine (NE) from perivascular postganglionic sympathetic neurons. RSD is often precipitated by this sequence: traumatic arterial spasm, regional ischemia, neurogenic inflammation, and ischemic/edematous damage to membranes of preterminal perivascular nociceptive neurons. In the natural repair of these membranes, it is suggested that adrenoceptors appear and are ordinarily transitory; but in RSD, they are retained by the increased adjacent NE. This process delays further healing, produces pain, and releases inflammatory substances, resulting in interacting pathophysiologic vicious cycles.

Prolonged relief of tic douloureux from partial root destruction is associated with localized analgesia

Fifty-eight patients who had been relieved of tic douloureux (TD) for least 3 years after partial destruction of the trigeminal sensory root by injection of minimal amounts of alcohol were reexamined 3 1/2 to 21 years after treatment. Of 41 patients still in remission at a median of 10 years after treatment, 32 had analgesia; i.e., sensation of pain from pinprick was absent in all 52 originally neuralgic areas. The other 9 patients in remission had some pain on pinprick in their neuralgic areas. In contrast, of 17 patients with recurrence of TD 3 1/2 to 11 years (median, 6 years) after treatment, at least 15 had demonstrable pain on pinprick in the neuralgic areas. It is concluded that continuing absence of pain on pinprick in the affected facial mucocutaneous area (or areas) is associated with prolonged relief of tic douloureux.

Precise selective alcoholic Gasserian injection for tic douloureux. Recent advances in technic and results

The Ecker-Perl method of alcoholic trigeminal rhizolysis has proved to be a safe and effective method of treating tic douloureux in a consecutive series of 324 patients over a period of 21 years.