Orthopedic aspects of familial insensitivity to pain due to a novel nerve growth factor beta mutation

The Implications of Brain-Derived Neurotrophic Factor in the Biological Activities of Platelet-Rich Plasma

Platelet-rich plasma (PRP) is a biological blood-derived therapeutic obtained from whole blood that contains higher levels of platelets. PRP has been primarily used to mitigate joint degeneration and chronic pain in osteoarthritis (OA). This clinical applicability is based mechanistically on the release of several proteins by platelets that can restore joint homeostasis. Platelets are the primary source of brain-derived neurotrophic factor (BDNF) outside the central nervous system. Interestingly, BDNF and PRP share key biological activities with clinical applicability for OA management, such as anti-inflammatory, anti-apoptotic, and antioxidant. However, the role of BDNF in PRP therapeutic activities is still unknown. Thus, this work aimed to investigate the implications of BDNF in therapeutic outcomes provided by PRP therapy in vitro and in-vivo, using the MIA-OA animal model in male Wistar rats. Initially, the PRP was characterized, obtaining a leukocyte-poor-platelet-rich plasma (LP-PRP). Our assays indicated that platelets activated by Calcium release BDNF, and suppression of M1 macrophage polarization induced by LP-PRP depends on BDNF full-length receptor, Tropomyosin Kinase-B (TrkB). OA animals were given LP-PRP intra-articular and showed functional recovery in gait, joint pain, inflammation, and tissue damage caused by MIA. Immunohistochemistry for activating transcriptional factor-3 (ATF-3) on L4/L5 dorsal root ganglia showed the LP-PRP decreased the nerve injury induced by MIA. All these LP-PRP therapeutic activities were reversed in the presence of TrkB receptor antagonist. Our results suggest that the therapeutic effects of LP-PRP in alleviating OA symptoms in rats depend on BDNF/TrkB activity.

Bilateral Total Knee Arthroplasties in a Patient with Bilateral Below-Knee Amputations and Osseointegration Limb Replacements: A Case Report

CASE

A 38-year-old man with congenital pain insensitivity underwent bilateral below-knee amputations. After his subsequent bilateral osseointegration (OI) limb replacements, he rapidly developed severe bilateral knee arthritis and varus deformity. In lieu of performing bilateral above-knee amputations, he underwent bilateral staged total knee arthroplasties (TKA) with excellent clinical and radiographic evaluation at 1-year follow-up.

CONCLUSION

To address both the limited bone stock and OI implant stem location, TKA after OI limb replacement in congenital pain insensitivity patients can be successfully achieved with a nonkeeled cementless tibial component and augmentation with a tibial cone.

From the Destruction of Two Lumbar Segments to Thoracic-Lumbar-Pelvic Fusion: A Case Caused by Congenital Insensitivity to Pain with Anhidrosis and Literature Review

BACKGROUND

Congenital insensitivity to pain with anhidrosis (CIPA) with Charcot arthropathy is a rare combination in orthopaedic clinical practice. The experience dealing with such patients is limited. Here with this case of approximately 10 years follow-up, we wish to shed light on the choices of strategies of surgeries and alerting clinicians with post-surgery complications. The possible underlying reasons for the recurrent Charcot arthropathies as well as strategies for peri-operative management for such surgical cases are also discussed.

CASE PRESENTATION

The patient underwent a surgery to correct her severe kyphosis caused by CIPA-related Charcot spine. Multiple post-surgery complications occurred during her follow-up, including hardware migration, adjacent segment disease (ASD), and loosening pedicle screws. Five revision surgeries were conducted consequently. From the limited experience on the management of CIPA-related Charcot spine, surgical correction is still the first-line treatment.

CONCLUSIONS

Of all the 16 cases reviewed (including our case), loosening pedicle screws, hardware migration, and ASDs are the common post-surgery complications. Large-scale removal of damaged vertebrae and subsequent reconstruction are not recommended, which might increase the risk of hardware migration. A 360° long-segment fusion might be of help to reduce the risk of ASDs. In the meantime, comprehensive management including careful nursing, proper rehabilitation exercises, and treatments targeting bone mineral metabolism is also critical.

A rare case of hereditary sensory and autonomic neuropathy type II

We describe the follow-up of a 29-year-old man diagnosed with hereditary sensory and autonomic neuropathy type II, including the different complications that presented since his childhood. Despite efforts to maintain an optimal quality of life, the lack of an early diagnosis led to an unfavorable prognosis and life condition.

Arthroplasty of a Charcot Knee in a Patient With Congenital Insensitivity to Pain

Hereditary sensory and autonomic neuropathies (HSANs) include hereditary disorders that cause congenital insensitivity to pain. Moreover, patients diagnosed with such disorders are known to have genetic mutations that alter their deep pain sensation, making them more prone to developing bone and joint complications such as repetitive fractures, joint swelling, and Charcot arthropathy. Neuropathic arthropathy (Charcot joint) is a rare and relatively poorly understood condition; it is suggested to be caused by autonomic dysfunction and repetitive microtrauma and characterized by instability and joint destruction. Diagnosing the idiopathic Charcot joint is challenging and is considered to be a diagnosis of exclusion. In addition, there are limited cases of Charcot knees managed by arthroplasty. Patients with Charcot knees are commonly characterized by profound bone loss, diffuse synovitis, and instability in the knee joint. In this article, we report the case of a 13-year-old patient with known NTRK1 gene mutation who presented with recurrent knee joint swelling episodes and instability without pain. She was diagnosed with Charcot knee joint and underwent right hinged total knee replacement. At one-year follow-up, she continued to have good knee stability and an overall functional gait. Our findings suggest that managing Charcot knee joint with total knee replacement in patients with HSAN may show improvement in terms of stability, swelling, and overall gait.

Targeting Nerve Growth Factor for Pain Management in Osteoarthritis-Clinical Efficacy and Safety

Nerve growth factor (NGF) is a neurotrophin that mediates pain sensitization in pathologic states, including osteoarthritis. In clinical trials, antibodies to NGF reduce pain and improve physical function due to osteoarthritis of the knee or hip and have a long duration of action. Rapidly progressive osteoarthritis is a dose-dependent adverse event with these agents, and additional joint safety signals, such as subchondral insufficiency fractures and increased rates of total joint replacement, are reported. The effects on pain and potential mechanisms behind these joint events both are of considerable importance in the consideration of future use of anti-NGF therapies for osteoarthritis.

A missense point mutation in nerve growth factor (NGFR100W) results in selective peripheral sensory neuropathy

The R100W mutation in nerve growth factor is associated with hereditary sensory autonomic neuropathy V in a Swedish family. These patients develop severe loss of perception to deep pain but with apparently normal cognitive functions. To better understand the disease mechanism, we examined a knockin mouse model of HSAN V. The homozygous mice showed significant structural deficits in intra-epidermal nerve fibers (IENFs) at birth. These mice had a total loss of pain perception at ∼2 months of age and often failed to survive to adulthood. Heterozygous mutant mice developed a progressive degeneration of small sensory fibers both behaviorally and functionally: they showed a progressive loss of IENFs starting at the age of 9 months accompanied with progressive loss of perception to painful stimuli such as noxious temperature. Quantitative analysis of lumbar 4/5 dorsal root ganglia revealed a significant reduction in small size neurons, while analysis of sciatic nerve fibers revealed the heterozygous mutant mice had no reduction in myelinated nerve fibers. Significantly, the amount of NGF secreted from mouse embryonic fibroblasts were reduced from both heterozygous and homozygous mice compared to their wild-type littermates. Interestingly, the heterozygous mice showed no apparent structural alteration in the brain: neither the anterior cingulate cortex nor the medial septum including NGF-dependent basal forebrain cholinergic neurons. Accordingly, these animals did not develop appreciable deficits in tests for brain function. Our study has thus demonstrated that the NGFR100W mutation likely affects the structure and function of peripheral sensory neurons.

Mutation Carriers with Reduced C-Afferent Density Reveal Cortical Dynamics of Pain-Action Relationship during Acute Pain

The evidence that action shapes perception has become widely accepted, for example, in the domain of vision. However, the manner in which action-relevant factors might influence the neural dynamics of acute pain processing has remained underexplored, particularly the functional roles of anterior insula (AI) and midanterior cingulate cortex (mid-ACC), which are frequently implicated in acute pain. To address this, we examined a unique group of heterozygous carriers of the rare R221W mutation on the nerve growth factor (NGF) gene. R221W carriers show a congenitally reduced density of C-nociceptor afferent nerves in the periphery, but can nonetheless distinguish between painful and nonpainful stimulations. Despite this, carriers display a tendency to underreact to acute pain behaviorally, thus exposing a potential functional gap in the pain–action relationship and allowing closer investigation of how the brain integrates pain and action information. Heterozygous R221W carriers and matched controls performed a functional magnetic resonance imaging (fMRI) task designed to dissociate stimulus type (painful or innocuous) from current behavioral relevance (relevant or irrelevant), by instructing participants to either press or refrain from pressing a button during thermal stimulation. Carriers’ subjective pain thresholds did not differ from controls’, but the carrier group showed decreased task accuracy. Hemodynamic activation in AI covaried with task performance, revealing a functional role in pain–action integration with increased responses for task-relevant painful stimulation (“signal,” requiring button-press execution) over task-irrelevant stimulation (“noise,” requiring button-press suppression). As predicted, mid-ACC activation was associated with action execution regardless of pain. Functional connectivity between AI and mid-ACC increased as a function of reported urge to withdraw from the stimulus, suggesting a joint role for these regions in motivated action during pain. The carrier group showed greater activation of primary sensorimotor cortices—but not the AI and mid-ACC regions—during pain and action, suggesting compensatory processing. These findings indicate a critical role for the AI–mid-ACC axis in supporting a flexible, adaptive action selection during pain, alongside the accompanying subjective experience of an urge to escape the pain.

No pain, no gain? The effects of pain-promoting neuropeptides and neurotrophins on fracture healing

Neuropeptides and neurotrophins are key regulators of peripheral nociceptive nerves and contribute to the induction, sensitization, and maintenance of pain. It is now known that these peptides also regulate non-neuronal tissues, including bone. Here, we review the effects of numerous neuropeptides and neurotrophins on fracture healing. The neuropeptides calcitonin-gene related peptide (CGRP), substance P (SP), vasoactive intestinal peptide (VIP), and pituitary adenylate cyclase-activating peptide (PACAP) have varying effects on osteoclastic and osteoblastic activity. Ultimately, CGRP and SP both accelerate fracture healing, while VIP and PACAP seem to negatively impact healing. Unlike the aforementioned neuropeptides, the neurotrophins nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) have more uniform effects. Both factors upregulate osteoblastic activity, osteoclastic activity, and, in vivo, stimulate osteogenesis to promote fracture healing. Future research will need to clarify the exact mechanism by which the neuropeptides and neurotrophins influence fracture healing. Specifically, understanding the optimal expression patterns for these proteins in the fracture healing process may lead to therapies that can maximize their bone-healing capabilities and minimize their pain-promoting effects. Finally, further examination of protein-sequestering antibodies and/or small molecule agonists and antagonists may lead to new therapies that can decrease the rate of delayed union/nonunion outcomes and fracture-associated pain.

An ultrafast system for signaling mechanical pain in human skin

The canonical view is that touch is signaled by fast-conducting, thickly myelinated afferents, whereas pain is signaled by slow-conducting, thinly myelinated ("fast" pain) or unmyelinated ("slow" pain) afferents. While other mammals have thickly myelinated afferents signaling pain (ultrafast nociceptors), these have not been demonstrated in humans. Here, we performed single-unit axonal recordings (microneurography) from cutaneous mechanoreceptive afferents in healthy participants. We identified A-fiber high-threshold mechanoreceptors (A-HTMRs) that were insensitive to gentle touch, encoded noxious skin indentations, and displayed conduction velocities similar to A-fiber low-threshold mechanoreceptors. Intraneural electrical stimulation of single ultrafast A-HTMRs evoked painful percepts. Testing in patients with selective deafferentation revealed impaired pain judgments to graded mechanical stimuli only when thickly myelinated fibers were absent. This function was preserved in patients with a loss-of-function mutation in mechanotransduction channel PIEZO2. These findings demonstrate that human mechanical pain does not require PIEZO2 and can be signaled by fast-conducting, thickly myelinated afferents.

Hereditary Sensory and Autonomic Neuropathies: Adding More to the Classification

PURPOSE OF REVIEW

Hereditary sensory and autonomic neuropathies (HSANs) are a clinically heterogeneous group of inherited neuropathies featuring prominent sensory and autonomic involvement. Classification of HSAN is based on mode of inheritance, genetic mutation, and phenotype. In this review, we discuss the recent additions to this classification and the important updates on management with a special focus on the recently investigated disease-modifying agents.

RECENT FINDINGS

In this past decade, three more HSAN types were added to the classification creating even more diversity in the genotype-phenotype. Clinical trials are underway for disease-modifying and symptomatic therapeutics, targeting mainly HSAN type III. Obtaining genetic testing leads to accurate diagnosis and guides focused management in the setting of such a diverse and continuously growing phenotype. It also increases the wealth of knowledge on HSAN pathophysiologies which paves the way toward development of targeted genetic treatments in the era of precision medicine.

Targeted Mutation (R100W) of the Gene Encoding NGF Leads to Deficits in the Peripheral Sensory Nervous System

Nerve growth factor (NGF) exerts multifaceted functions through different stages of life. A missense mutation (R100W) in the beta-NGF gene was found in hereditary sensory autonomic neuropathy V (HSAN V) patients with severe loss of pain perception but without overt cognitive impairment. To better understand the pathogenesis of HSAN V, we generated the first NGFR100W knock in mouse model for HSAN V. We found that the homozygotes exhibited a postnatal lethal phenotype. A majority of homozygous pups died within the first week. Some homozygous pups could ingest more milk and survived up to 2 months by reducing litter size. Whole mount in situ hybridization using E10.5 embryos revealed that, compared to wild type, R100W mutation did not alter the gene expression patterns of TrkA and P75NTR in the homozygotes. We also found that the homozygotes displayed normal embryonic development of major organs (heart, lung, liver, kidney, and spleen). Furthermore, the homozygotes exhibited severe loss of PGP9.5-positive intra-epidermal sensory fibers. Taken together, our results suggest that, as with HSAN V patients, the R100W mutation primarily affects the peripheral sensory nervous system in the mouse model. This novel mouse model makes it possible to further study in vivo how NGFR100W uncouple trophic function from nociception of NGF.

Charcot spinal arthropathy in patients with congenital insensitivity to pain: a report of two cases and review of the literature

Charcot spine, or neuropathic spinal arthropathy, involves the progressive destruction of the spinal joint due to the lack of normal protective sensations and proprioception. A rare cause of Charcot spine is congenital insensitivity to pain, which is an absent or abnormal response to painful stimuli. There are few case reports describing this condition, and long-term follow-up data are limited. The presentation and treatment of two patients with Charcot spine secondary to congenital insensitivity to pain are described. Both cases were characterized by lumbar involvement and were treated with circumferential decompression and an extended lumbo-pelvic fusion construct. The cases described here demonstrate stable neurological status at 1.5 and 5 years follow-up. Patient characteristics, pre- and post-operative imaging, operative approach, and outcomes are described. The literature regarding this rare condition is also reviewed, with an emphasis on operative management and outcomes. Surgical management is traditionally complicated by a high rate of hardware failure and adjacent segment degeneration. The current review highlights the importance of prompt and aggressive management following diagnosis of Charcot spine, as well as extended follow-up.

Rare human nerve growth factor-β mutation reveals relationship between C-afferent density and acute pain evaluation

The rare nerve growth factor-β (NGFB) mutation R221W causes a selective loss of thinly myelinated fibers and especially unmyelinated C-fibers. Carriers of this mutation show altered pain sensation. A subset presents with arthropathic symptoms, with the homozygous most severely affected. The aim of the present study was to investigate the relationship between peripheral afferent loss and pain evaluation by performing a quantification of small-fiber density in the cornea of the carriers, relating density to pain evaluation measures. In vivo corneal confocal microscopy (CCM) was used to quantify C-fiber loss in the cornea of 19 R221W mutation carriers (3 homozygous) and 19 age-matched healthy control subjects. Pain evaluation data via the Situational Pain Questionnaire (SPQ) and the severity of neuropathy based on the Neuropathy Disability Score (NDS) were assessed. Homozygotes, heterozygotes, and control groups differed significantly in corneal C-nerve fiber density, with the homozygotes showing a significant afferent reduction. Importantly, peripheral C-fiber loss correlated negatively with pain evaluation, as revealed by SPQ scores. This study is the first to investigate the contribution of small-fiber density to the perceptual evaluation of pain. It demonstrates that the lower the peripheral small-fiber density, the lower the degree of reported pain intensity, indicating a functional relationship between small-fiber density and higher level pain experience.

Hereditary sensory and autonomic neuropathy types 4 and 5: Review and proposal of a new rehabilitation method

Although pain is unpleasant, it should serve as a reminder for individuals to avoid similar damaging incidents in the future. Hereditary sensory and autonomic neuropathy (HSAN) includes genetic disorders involving various sensory and autonomic dysfunctions. They are classified by the mode of inheritance, clinical features, and related genes. HSAN type 4 (HSAN-4) and type 5 (HSAN-5) are characterized by insensitivity to pain and thermal sensation. Further, HSAN-4 is accompanied by decreased sweating and intellectual disabilities. These characteristics of HSAN-4 and -5 result in many clinical features, such as pediatric, psychiatric, orthopedic, oral, dermatological, and ophthalmological problems. Orthopedic problems include destructive injuries such as multiple fractures and joint dislocation. Studies on gait have shown greater speed and higher heel contact angular velocity in HSAN-4 and -5 patients compared with controls. Studies on grasp-lift-holding tasks have shown higher grasp force and fluctuations in acceleration of the object. We believe that these findings represent outcomes of deficient motor learning. We propose a new rehabilitation method for patients with HSAN-4 and -5, with the aim of decreasing their destructive injuries.

Pain in the Blood? Envisioning Mechanism-Based Diagnoses and Biomarkers in Clinical Pain Medicine

Chronic pain is highly prevalent, and pain medicine lacks objective biomarkers to guide diagnosis and choice of treatment. The current U.S. “opioid epidemic” is a reminder of the paucity of effective and safe treatment options. Traditional pain diagnoses according to the International Classification of Diseases are often unspecific, and analgesics are often prescribed on a trial-and-error basis. In contrast to this current state of affairs, the vision of future mechanism-based diagnoses of chronic pain conditions is presented in this non-technical paper, focusing on the need for biomarkers and the theoretical complexity of the task. Pain is and will remain a subjective experience, and as such is not objectively measurable. Therefore, the concept of “noci-marker” is presented as an alternative to “pain biomarker”, the goal being to find objective, measurable correlates of the pathophysiological processes involved in different chronic pain conditions. This vision entails a call for more translational pain research in order to bridge the gap between clinical pain medicine and preclinical science.

Hereditary sensory and autonomic neuropathy types IV and V in Japan

Hereditary sensory and autonomic neuropathy (HSAN) is a group of genetic disorders involving varying sensory and autonomic dysfunction. HSAN types IV and V are characterized by congenital generalized loss of pain and thermal sensation. HSAN type IV is additionally accompanied by decreased sweating and intellectual disability. From 2010 to 2013, we (members of the Japanese Research Group on Congenital Insensitivity to Pain) carried out research on HSAN types IV and V. Research by this group included epidemiological data, examination of clinical findings, solutions of disease etiology, investigation of complications and development of their management. Complications were categorized into musculoskeletal complications, oral/dental complications, dermal complications, ocular complications, complications resulting from impaired thermal control, anesthetic considerations, other complications possibly related to autonomic dysfunction, and abnormal mental development and behavior. Treatment and care for patients with HSAN types IV and V require a wide range of knowledge and experience, and a multidisciplinary team approach. Therefore, we produced the "Guideline of Total Management and Care for Congenital Insensitivity to Pain (Ver.1)" in 2012, to provide information for medical specialists based on our knowledge and experience. This guideline includes medical issues, as well as descriptions of social participation and welfare. This review outlines the situation of HSAN types IV and V in Japan, and the recommendations of treatment and care for patients, mostly based on research conducted by the Japanese Research Group.

Exuberant sprouting of sensory and sympathetic nerve fibers in nonhealed bone fractures and the generation and maintenance of chronic skeletal pain

Skeletal injury is a leading cause of chronic pain and long-term disability worldwide. While most acute skeletal pain can be effectively managed with nonsteroidal anti-inflammatory drugs and opiates, chronic skeletal pain is more difficult to control using these same therapy regimens. One possibility as to why chronic skeletal pain is more difficult to manage over time is that there may be nerve sprouting in nonhealed areas of the skeleton that normally receive little (mineralized bone) to no (articular cartilage) innervation. If such ectopic sprouting did occur, it could result in normally nonnoxious loading of the skeleton being perceived as noxious and/or the generation of a neuropathic pain state. To explore this possibility, a mouse model of skeletal pain was generated by inducing a closed fracture of the femur. Examined animals had comminuted fractures and did not fully heal even at 90+days post fracture. In all mice with nonhealed fractures, exuberant sensory and sympathetic nerve sprouting, an increase in the density of nerve fibers, and the formation of neuroma-like structures near the fracture site were observed. Additionally, all of these animals exhibited significant pain behaviors upon palpation of the nonhealed fracture site. In contrast, sprouting of sensory and sympathetic nerve fibers or significant palpation-induced pain behaviors was never observed in naïve animals. Understanding what drives this ectopic nerve sprouting and the role it plays in skeletal pain may allow a better understanding and treatment of this currently difficult-to-control pain state.

Congenital insensitivity to pain in a child attending a paediatric fracture clinic

Congenital insensitivity to pain is a rare condition that is often undiagnosed until patients present with a variety of musculoskeletal problems. A major sequel of these orthopaedic manifestations is the development of heterotopic ossification and callus formation following fractures, eventually leading to the development of a Charcot's joint. This case reports on a 7-year-old child who was diagnosed with congenital insensitivity to pain type V, after he presented in our clinic with fractures of the metatarsals in his left foot while continuing to weight bear, without any discomfort. The patient failed to attend the follow-up in paediatric neurology clinic despite multiple invitations. This case highlights the importance of establishing an early diagnosis and keeping a close eye on this rare entity, which can present for the first time in a paediatric fracture clinic.

Hereditary sensory and autonomic neuropathy type IV and orthopaedic complications

Hereditary sensory and autonomic neuropathy type IV (HSAN-IV) is a very rare autosomal recessive disorder characterized by recurrent episodes of unexplained fever, extensive anhidrosis, total insensitivity to pain, hypotonia, and mental retardation. The most frequent complications of this disease are corneal scarring, multiple fractures, joint deformities, osteomyelitis, and disabling self-mutilations. We reported the case of a 12-year-old boy. The goal was to discuss our decision-making and compare this case with cases described in the literature.

Consanguineous marriage and increased risk of idiopathic congenital talipes equinovarus: a case-control study in a rural area

BACKGROUND

The purpose of this study is to evaluate if there is any relationship between consanguineous marriages and idiopathic congenital talipes equinovarus (CTEV).

METHODS

A case-control study on CTEV screening was conducted in a rural eastern city of Turkey between 2009 and 2011 and a total of 28 cases (infants with idiopathic CTEV) and 575 controls (healthy infants) were recruited. Sociodemographic status of the infants, including gestational age and birth weights, maternal characteristics and, if any, the degree of consanguinity, were recorded. As an inclusion criterion, only singleton, full-term, live births were accepted. A backward stepwise logistic regression model was used to evaluate the relationship between idiopathic CTEV and parental consanguinity. Unadjusted and adjusted odds ratios (OR) with 95% confidence interval (CI) were calculated.

RESULTS

Among maternal and infant characteristics, significant risk factors for idiopathic CTEV in the regression analysis were work status (employed), consanguineous marriage, sex (male), and gestational age (>42 wk). Babies born to first-cousin parents had >4 times the risk of idiopathic CTEV [OR, 4.138, (95% CI, 1.484, 11.538)] and the risk for those born to distant relatives was 2.9 times higher [OR, 2.941, (95% CI, 1.070, 8.087)] than for children of unrelated parents.

CONCLUSIONS

Consanguineous marriage was significantly associated with an increased risk of idiopathic CTEV. This association remained significant even after adjusting for potential confounding variables. To obtain more accurate results, a population-based screening study with an increased number of cases and controls should be performed in future studies.

LEVEL OF EVIDENCE

Case-control study investigating the effect of a patient characteristic on the outcome of disease (level-III).

A novel NGF mutation clarifies the molecular mechanism and extends the phenotypic spectrum of the HSAN5 neuropathy

Background

Nerve growth factor β (NGFβ) and tyrosine kinase receptor type A (TRKA) are a well studied neurotrophin/receptor duo involved in neuronal survival and differentiation. The only previously reported hereditary sensory neuropathy caused by an NGF mutation, c.661C>T (HSAN5), and the pathology caused by biallelic mutations in the TRKA gene (NTRK1) (HSAN4), share only some clinical features. A consanguineous Arab family, where five of the six children were completely unable to perceive pain, were mentally retarded, did not sweat, could not discriminate temperature, and had a chronic immunodeficiency, is reported here. The condition is linked to a new homozygous mutation in the NGF gene, c.[680C>A]+[681_682delGG].

Methods

Genetic linkage and standard sequencing techniques were used to identify the causative gene. Using wild-type or mutant over-expression constructs transfected into PC12 and COS-7 cells, the cellular and molecular consequences of the mutations were investigated.

Results

The mutant gene produced a precursor protein V232fs that was unable to differentiate PC12 cells. V232fs was not secreted from cells as mature NGFβ.

Conclusions

Both the clinical and cellular data suggest that the c.[680C>A]+[681_682delGG] NGF mutation is a functional null. The HSAN5 phenotype is extended to encompass HSAN4-like characteristics. It is concluded that the HSAN4 and HSAN5 phenotypes are parts of a phenotypic spectrum caused by changes in the NGF/TRKA signalling pathway.

Routine MRI findings of the asymptomatic foot in diabetic patients with unilateral Charcot foot

BACKGROUND

Imaging studies of bones in patients with sensory deficits are scarce.

AIM

To investigate bone MR images of the lower limb in diabetic patients with severe sensory polyneuropathy, and in control subjects without sensory deficits.

METHODS

Routine T1 weighted and T2-fat-suppressed-STIR-sequences without contrast media were performed of the asymptomatic foot in 10 diabetic patients with polyneuropathy and unilateral inactive Charcot foot, and in 10 matched and 10 younger, non-obese unmatched control subjects. Simultaneously, a Gadolinium containing phantom was also assessed for reference. T1 weighted signal intensity (SI) was recorded at representative regions of interest at the peritendineal soft tissue, the tibia, the calcaneus, and at the phantom. Any abnormal skeletal morphology was also recorded.

RESULTS

Mean SI at the soft tissue, the calcaneus, and the tibia, respectively, was 105%, 105% and 84% of that at the phantom in the matched and unmatched control subjects, compared to 102% (soft tissue), 112% (calcaneus) and 64% (tibia) in the patients; differences of tibia vs. calcaneus or soft tissue were highly significant (p < 0.005). SI at the tibia was lower in the patients than in control subjects (p < 0.05). Occult traumatic skeletal lesions were found in 8 of the 10 asymptomatic diabetic feet (none in the control feet).

CONCLUSION

MR imaging did not reveal grossly abnormal bone marrow signalling in the limbs with severe sensory polyneuropathy, but occult sequelae of previous traumatic injuries.

Orthodontic treatment and management of limited mouth opening and oral lesions in a patient with congenital insensitivity to pain: case report

Congenital insensitivity to pain is a rare clinical syndrome characterized by dramatic impairment of pain perception since birth and is generally caused by a hereditary sensory and autonomic neuropathy with loss of the small-calibre, nociceptive nerve fibres. We report a 9-year-old case, with a generalized congenital insensitivity to pain. The patient was referred to our Department by a private orthodontist for severe limited mouth opening and multiple oral ulcers which greatly worsened after starting the orthodontic treatment. The management of his oral lesions of the limited mouth opening and of the orthodontic treatment are described. The management approach aimed to improve mandibular range of motion and associated stretching and a self-modeling mouthguard to avoid cheek self-biting. This protocol allowed continuing the orthodontic treatment to restore the occlusion. Finally, good occlusion, normal function and better quality of patient's life were achieved.

Fracture mechanisms and fracture pattern in men and women aged 50 years and older: a study of a 12-year population-based injury register, Umeå, Sweden

In a study of a 12-year population-based injury register, Umeå, Sweden, we analyzed the fracture mechanisms and fracture pattern in men and women 50 years and older. Low-energy trauma was responsible for the major and costliest part of the fracture panorama, but the pattern differs between age groups.

INTRODUCTION

Osteoporosis-related fracture is a major health problem: the number of hip fractures is expected to double to 2030. While osteoporosis is one of many risk factors, trauma is almost always involved. Therefore, we analyzed injury mechanisms in patients aged over 50.

METHODS

We registered injury mechanism, cause, diagnosis in all trauma patients at Umeå University hospital, Sweden. This population-based register (1993-2004) comprises a total of 113,668 injuries (29,189 fractures). Patients >or=50 years contributed to 13,279 fractures.

RESULTS

Low-energy trauma (fall <1 m) caused 53% of all fractures >or=50 years and older. In those over 75 low-energy trauma caused >80%. The seasonal variation of fractures was maximally 25%. With increasing age, proximal fractures became more common, in both upper and lower extremities. Proximal locations predominate in older age groups.

CONCLUSIONS

Low-energy trauma was responsible for the largest and costliest part of the fracture panorama. In fact, almost all fractures in middle-aged and old people were caused by low-energy mechanisms; thus, most fractures in these patients have a fragility component, and the contribution of osteoporosis-related fractures is more important than previously thought. A better understanding of injury mechanisms also in low-energy trauma is a prerequisite for preventive interventions.

Nonoperative treatment of neuro-osteoarthropathy of the foot: do we need new criteria?

The worst manifestation of neuro-osteoarthropathy of the pain-insensitive foot is the Charcot foot with its devastating osteoarticular destructions and irreversible deformities. New diagnostic tools such as MRI have revealed that mechanical injury and overuse is the origin of the condition. Traditionally, only feet with bone and joint damage apparent on plain radiographs (fracture and dislocation injuries) have undergone nonoperative treatment with off-loading and immobilization; however, treating painless, seemingly asymptomatic nonfracture injuries (bone bruise or bone marrow edema) with off-loading and immobilization has proven highly effective in preventing the Charcot foot. Whether pharmaceutical treatment has a role in terms of prevention or healing of osteoarticular destructions remains to be demonstrated.

Genetic predictors of acute and chronic pain

Although broad agreement exists that genetic factors are important contributors to individual differences in pain sensitivity and risk for developing painful clinical conditions, the field of pain genetics is still in its infancy. This article reviews recent human studies of the genetics of acute and chronic pain, which implicate polymorphisms in genes coding for catechol-O-methyltransferase activity and micro-opioid receptors, among a number of others, as influential in explaining variability among the pain responses of individuals. Growing interest in pain genetics and accelerating methodologic advances in the field will almost certainly alter our understanding of which genes contribute to nociception and how dynamic interactions between multiple genes and environmental events shape the human experience of pain.