Bioinformatics-Based Identification of Expanded Repeats: A Non-reference Intronic Pentamer Expansion in RFC1 Causes CANVAS

Genomic technologies such as next-generation sequencing (NGS) are revolutionizing molecular diagnostics and clinical medicine. However, these approaches have proven inefficient at identifying pathogenic repeat expansions. Here, we apply a collection of bioinformatics tools that can be utilized to identify either known or novel expanded repeat sequences in NGS data. We performed genetic studies of a cohort of 35 individuals from 22 families with a clinical diagnosis of cerebellar ataxia with neuropathy and bilateral vestibular areflexia syndrome (CANVAS). Analysis of whole-genome sequence (WGS) data with five independent algorithms identified a recessively inherited intronic repeat expansion [(AAGGG)exp] in the gene encoding Replication Factor C1 (RFC1). This motif, not reported in the reference sequence, localized to an Alu element and replaced the reference (AAAAG)11 short tandem repeat. Genetic analyses confirmed the pathogenic expansion in 18 of 22 CANVAS-affected families and identified a core ancestral haplotype, estimated to have arisen in Europe more than twenty-five thousand years ago. WGS of the four RFC1-negative CANVAS-affected families identified plausible variants in three, with genomic re-diagnosis of SCA3, spastic ataxia of the Charlevoix-Saguenay type, and SCA45. This study identified the genetic basis of CANVAS and demonstrated that these improved bioinformatics tools increase the diagnostic utility of WGS to determine the genetic basis of a heterogeneous group of clinically overlapping neurogenetic disorders.

Periventricular White Matter Abnormalities on Diffusion Tensor Imaging of Postural Instability Gait Disorder Parkinsonism

BACKGROUND AND PURPOSE

Postural instability gait disorder is a motor subtype of Parkinson disease associated with predominant gait dysfunction. We investigated the periventricular white matter comprising longitudinal, thalamic, and callosal fibers using diffusion tensor MR Imaging and examined clinical correlates in a cohort of patients with Parkinson disease and postural instability gait disorder and healthy controls.

MATERIALS AND METHODS

All subjects underwent the Tinetti Gait and Balance Assessment and brain MR imaging. The DTI indices (fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity) from ROIs dropped over the superior and inferior longitudinal fasciculi, inferior fronto-occipital fasciculus, anterior thalamic radiation, anterior and posterior limbs of the internal capsule, and the genu and body of corpus callosum were evaluated.

RESULTS

Our findings showed that the superior longitudinal fasciculus, inferior longitudinal fasciculus, inferior fronto-occipital fasciculus, anterior thalamic radiation, genu of the corpus callosum, and body of the corpus callosum are more affected in postural instability gait disorder than in those with Parkinson disease or healthy controls, with more group differences among the longitudinal fibers. Only the callosal fibers differentiated the postural instability gait disorder and Parkinson disease groups. DTI measures in the superior longitudinal fasciculus, frontostriatal fibers (anterior thalamic radiation, anterior limb of the internal capsule), and genu of the corpus callosum fibers correlated with clinical gait severity.

CONCLUSIONS

Findings from this case-control cohort lend further evidence to the role of extranigral pathology and, specifically, the periventricular fibers in the pathophysiology of postural instability gait disorder.

Evaluation of the cutaneous sensation of the face in patients with different clinical forms of leprosy

Background

Leprosy can be considered to be the most common peripheral neuropathy of infectious etiology and constitutes a public health problem. The standard routine examination for assessing sensory impairment in leprosy neuropathy basically evaluates hands, feet and eyes. However, evaluation of facial cutaneous sensation is not routinely performed.

Objectives

The aim of this study was to evaluate facial cutaneous sensation in patients with different clinical forms of leprosy and compare the findings with those from healthy individuals.

Methodology

19 healthy controls and 71 leprosy patients who were being treated at a national reference center for leprosy in Brazil underwent facial sensation assessment using the Semmes-Weinstein monofilament test. This test was applied over the facial areas corresponding to the ophthalmic, maxillary and mandibular distal branches of the trigeminal nerve.

Results

The predominant clinical form in terms of changes to facial cutaneous sensation was lepromatous leprosy (LL), followed by the borderline-borderline (BB), and borderline-lepromatous (BL) forms, in comparison with healthy individuals. The distal branches most affected were the zygomatic (28.2%; 20/71), buccal (23.9%; 17/71) and nasal (22.5%; 16/71). There was asymmetrical sensory impairment of the face in 62.5% (20/32) of the cases.

Conclusion

The face is just as impaired in leprosy as are the feet, hands and eyes, but facial impairment is underdiagnosed. Our evaluation on the different sensory branches and evidence of asymmetrical impairment of the face confirm the classically described pattern of leprosy neuropathy, i.e. consisting of asymmetrical and predominantly sensory peripheral neuropathy.

Pathobiology of Christianson syndrome: Linking disrupted endosomal-lysosomal function with intellectual disability and sensory impairments

Christianson syndrome (CS) is a recently described rare neurogenetic disorder presenting early in life with a broad range of neurological symptoms, including severe intellectual disability with nonverbal status, hyperactivity, epilepsy, and progressive ataxia due to cerebellar atrophy. CS is due to loss-of-function mutations in SLC9A6, encoding NHE6, a sodium-hydrogen exchanger involved in the regulation of early endosomal pH. Here we review what is currently known about the neuropathogenesis of CS, based on insights from experimental models, which to date have focused on mechanisms that affect the CNS, specifically the brain. In addition, parental reports of sensory disturbances in their children with CS, including an apparent insensitivity to pain, led us to explore sensory function and related neuropathology in Slc9a6 KO mice. We present new data showing sensory deficits in Slc9a6 KO mice, which had reduced behavioral responses to noxious thermal and mechanical stimuli (Hargreaves and Von Frey assays, respectively) compared to wild type (WT) littermates. Immunohistochemical and ultrastructural analysis of the spinal cord and peripheral nervous system revealed intracellular accumulation of the glycosphingolipid GM2 ganglioside in KO but not WT mice. This cellular storage phenotype was most abundant in neurons of lamina I-II of the dorsal horn, a major relay site in the processing of painful stimuli. Spinal cords of KO mice also exhibited changes in astroglial and microglial populations throughout the gray matter suggestive of a neuroinflammatory process. Our findings establish the Slc9a6 KO mouse as a relevant tool for studying the sensory deficits in CS, and highlight selective vulnerabilities in relevant cell populations that may contribute to this phenotype. How NHE6 loss of function leads to such a multifaceted neurological syndrome is still undefined, and it is likely that NHE6 is involved with many cellular processes critical to normal nervous system development and function. In addition, the sensory issues exhibited by Slc9a6 KO mice, in combination with our neuropathological findings, are consistent with NHE6 loss of function impacting the entire nervous system. Sensory dysfunction in intellectually disabled individuals is challenging to assess and may impair patient safety and quality of life. Further mechanistic studies of the neurological impairments underlying CS and other genetic intellectual disability disorders must also take into account mechanisms affecting broader nervous system function in order to understand the full range of associated disabilities.

Levodopa response differs in Parkinson's motor subtypes: A task-based effective connectivity study

Parkinson's disease (PD) is a circuit-level disorder with clinically-determined motor subtypes. Despite evidence suggesting each subtype may have different pathophysiology, few neuroimaging studies have examined levodopa-induced differences in neural activation between tremor dominant (TD) and postural instability/gait difficulty (PIGD) subtype patients during a motor task. The goal of this functional MRI (fMRI) study was to examine task-induced activation and connectivity in the cortico-striatal-thalamo-cortical motor circuit in healthy controls, TD patients, and PIGD patients before and after levodopa administration. Fourteen TD and 12 PIGD cognitively-intact patients and 21 age- and sex-matched healthy controls completed a right-hand, paced tapping fMRI paradigm. Collectively, PD patients off medication (OFF) showed hypoactivation of the motor cortex relative to healthy controls, even when controlling for performance. After levodopa intake, the PIGD patients had significantly increased activation in the left putamen compared with TD patients and healthy controls. Psychophysiological interaction analysis revealed that levodopa increased effective connectivity between the posterior putamen and other areas of the motor circuit during tapping in TD patients, but not in PIGD patients. This novel, levodopa-induced difference in the neural responses between PD motor subtypes may have significant implications for elucidating the mechanisms underlying the distinct phenotypic manifestations and enabling the classification of motor subtypes objectively using fMRI.

Neonatal Restriction of Tactile Inputs Leads to Long-Lasting Impairments of Cross-Modal Processing

Optimal behavior relies on the combination of inputs from multiple senses through complex interactions within neocortical networks. The ontogeny of this multisensory interplay is still unknown. Here, we identify critical factors that control the development of visual-tactile processing by combining in vivo electrophysiology with anatomical/functional assessment of cortico-cortical communication and behavioral investigation of pigmented rats. We demonstrate that the transient reduction of unimodal (tactile) inputs during a short period of neonatal development prior to the first cross-modal experience affects feed-forward subcortico-cortical interactions by attenuating the cross-modal enhancement of evoked responses in the adult primary somatosensory cortex. Moreover, the neonatal manipulation alters cortico-cortical interactions by decreasing the cross-modal synchrony and directionality in line with the sparsification of direct projections between primary somatosensory and visual cortices. At the behavioral level, these functional and structural deficits resulted in lower cross-modal matching abilities. Thus, neonatal unimodal experience during defined developmental stages is necessary for setting up the neuronal networks of multisensory processing.

Reducing unisensory experience during neonatal development causes permanent disruption of connectivity between primary sensory cortices, resulting in impaired multisensory abilities.

Our senses, working together, enable us to interact with the environment. To obtain a unified percept of the world, diverse sensory inputs need to be bound together within distributed but strongly interconnected neuronal networks. Many multisensory abilities emerge or mature late in life, long after the maturation of the individual senses, yet the factors and mechanisms controlling their development are largely unknown. Here, we provide evidence for the critical role of unisensory experience during early postnatal life for the development of multisensory integration. Focusing on visual-tactile interactions in pigmented rats with good visual acuity, we show that a transient reduction of tactile inputs during neonatal development leads to sparser direct connections between adult primary visual and somatosensory cortices. As a result, these animals showed reduced neuronal activation following co-occurring tactile and visual stimuli, as well as impaired communication within visual-somatosensory networks. The structural and functional deficits resulting from an early manipulation of tactile experience had major behavioral consequences, impairing the rats’ ability to transfer information about encountered objects between senses. Thus, unisensory experience during early development shapes the neuronal networks of multisensory processing and the ability to transfer cross-modal information.

Case of the month: April 1998--30 year old male with perineal numbness

A 30-year-old male presented with a 2 year progressive course of bowel and bladder dysfunction, mild leg weakness and sensory abnormalities in sacral dermatomes. MRI showed an intra-axial conus medullaris lesion which was excised and identified as a ganglioglioma. The case presents the typical clinical course and histopathology of this unusual lesion which carries a favorable prognosis after gross total removal. Preoperative neurological function in such patients is highly predictive of post-operative outcome.

FMRI reveals abnormal central processing of sensory and pain stimuli in ill Gulf War veterans

Many veterans chronically ill from the 1991 Gulf War exhibit symptoms of altered sensation, including chronic pain. In this study of 55 veterans of a Construction Battalion previously examined in 1995-1996 and 1997-1998, brain activation to innocuous and noxious heat stimuli was assessed in 2008-2009 with a quantitative sensory testing fMRI protocol in control veterans and groups representing three syndrome variants. Testing outside the scanner revealed no significant differences in warm detection or heat pain threshold among the four groups. In the fMRI study, Syndrome 1 and Syndrome 2, but not Syndrome 3, exhibited hypo-activation to innocuous heat and hyper-activation to noxious heat stimuli compared to controls. The results indicate abnormal central processing of sensory and painful stimuli in 2 of 3 variants of Gulf War illness and call for a more comprehensive study with a larger, representative sample of veterans.

Requirement of mouse BCCIP for neural development and progenitor proliferation

Multiple DNA repair pathways are involved in the orderly development of neural systems at distinct stages. The homologous recombination (HR) pathway is required to resolve stalled replication forks and critical for the proliferation of progenitor cells during neural development. BCCIP is a BRCA2 and CDKN1A interacting protein implicated in HR and inhibition of DNA replication stress. In this study, we determined the role of BCCIP in neural development using a conditional BCCIP knock-down mouse model. BCCIP deficiency impaired embryonic and postnatal neural development, causing severe ataxia, cerebral and cerebellar defects, and microcephaly. These development defects are associated with spontaneous DNA damage and subsequent cell death in the proliferative cell populations of the neural system during embryogenesis. With in vitro neural spheroid cultures, BCCIP deficiency impaired neural progenitor's self-renewal capability, and spontaneously activated p53. These data suggest that BCCIP and its anti-replication stress functions are essential for normal neural development by maintaining an orderly proliferation of neural progenitors.

Development of animal model for vasculatic neuropathy: Induction by ischemic-reperfusion in the rat femoral artery

Ischemic-reperfusion (I/R) is common in various pathological conditions like diabetic complication, complex regional pain syndrome type II (CRPS II), necrotizing vascular occlusive disease and trauma. We have developed an animal model of ischemic-reperfusion injury induced nociceptive sensory neuropathy in rats. The model was validated after 2, 4 and 6h of ischemia followed by prolonged reperfusion. The sensory behavioral assessment revealed thermal and mechanical hyperalgesia in paw and in tail which expressed the peripheral and central neuropathic pain respectively. We observed a decrease in the serum IL-10 and nerve conduction velocity and increase in the serum nitrate, malondialdehyde (MDA) and TNF-alpha levels in the 4 and 6h I/R groups in biochemical and electrophysiological evaluations. Histopathological study had revealed the decrease in nerve fiber density in the moderate and severe I/R groups. We selected the moderate (4h) ischemic-reperfusion injury as beneficial model because of the good correlation with clinical status for the development of neuropathy in human associated with severe pain disorders. This model can be used to explore pathophysiological mechanisms implied in the genesis of neuropathic pain and also to evaluate the new analgesic agents, peripheral neuro-vasoactive substances and neuroprotective drugs.

Bilateral cervical contusion spinal cord injury in rats

There is increasing motivation to develop clinically relevant experimental models for cervical SCI in rodents and techniques to assess deficits in forelimb function. Here we describe a bilateral cervical contusion model in rats. Female Sprague-Dawley rats received mild or moderate cervical contusion injuries (using the Infinite Horizons device) at C5, C6, or C7/8. Forelimb motor function was assessed using a grip strength meter (GSM); sensory function was assessed by the von Frey hair test; the integrity of the corticospinal tract (CST) was assessed by biotinylated dextran amine (BDA) tract tracing. Mild contusions caused primarily dorsal column (DC) and gray matter (GM) damage while moderate contusions produced additional damage to lateral and ventral tissue. Forelimb and hindlimb function was severely impaired immediately post-injury, but all rats regained the ability to use their hindlimbs for locomotion. Gripping ability was abolished immediately after injury but recovered partially, depending upon the spinal level and severity of the injury. Rats exhibited a loss of sensation in both fore- and hindlimbs that partially recovered, and did not exhibit allodynia. Tract tracing revealed that the main contingent of CST axons in the DC was completely interrupted in all but one animal whereas the dorsolateral CST (dlCST) was partially spared, and dlCST axons gave rise to axons that arborized in the GM caudal to the injury. Our data demonstrate that rats can survive significant bilateral cervical contusion injuries at or below C5 and that forepaw gripping function recovers after mild injuries even when the main component of CST axons in the dorsal column is completely interrupted.

Impairment of postural control in rabbits with extensive spinal lesions

Our previous studies on rabbits demonstrated that the ventral spinal pathways are of primary importance for postural control in the hindquarters. After ventral hemisection, postural control did not recover, whereas after dorsal or lateral hemisection it did. The aim of this study was to examine postural capacity of rabbits after more extensive lesion (3/4 section of the spinal cord at T(12) level), that is, with only one ventral quadrant spared (VQ animals). They were tested before (control) and after lesion on the platform periodically tilted in the frontal plane. In control animals, tilts of the platform regularly elicited coordinated electromyographic (EMG) responses in the hindlimbs, which resulted in generation of postural corrections and in maintenance of balance. In VQ rabbits, the EMG responses appeared only in a part of tilt cycles, and they could be either correctly or incorrectly phased in relation to tilts. Because of a reduced value and incorrect phasing of EMG responses on both sides, this muscle activity did not cause postural corrective movements in the majority of rabbits, and the body swayed together with the platform. In these rabbits, the ability to perform postural corrections did not recover during the whole period of observation (< or =30 days). Low probability of correct EMG responses to tilts in most rabbits as well as an appearance of incorrect responses to tilts suggest that the spinal reflex chains, necessary for postural control, have not been specifically selected by a reduced supraspinal drive transmitted via a single ventral quadrant.

[Sensory syndrome and aphasia after left insular infarct]

INTRODUCTION

Sensorial impairment without hemiplegia is usually caused by a thalamic lesion.

CASE REPORT

A 28-year-old woman presented with hemianesthesia associated with aphasia following a left insular lesion, subsequent to subarachnoid hemorrhage. Brain MRI Flair sequence revealed a high intensity signal in the left insular and frontal subcortical regions. Insular infarct was diagnosed, associated with hemorrhagic sequelae.

DISCUSSION/CONCLUSION

Study of the normal and pathologic insular cortex suggest several implications of the region in somatosensory and language functions. However, the insular cortex has been mainly associated with central pain. Lasting objective hypoesthesia has been very rarely documented. The left insular cortex has also been implicated in speech apraxia but our patient presented with fluent aphasia mostly affecting the rhythm of speech, as it has been observed in thalamic aphasia.

Oculo-auriculo-vertebral spectrum: associated anomalies, functional deficits and possible developmental risk factors

Swedish patients with the oculo-auriculo-vertebral (OAV) spectrum participated in a prospective multidisciplinary investigation. The aims of the study were to describe their systemic and functional defects, especially autism spectrum disorders, and to search for possible etiologic risk factors. Available medical records were studied and the mothers answered a questionnaire on history of prenatal events. A clinical examination evaluating systemic findings, vision, hearing, speech, oral and swallowing function, and neuropsychiatric function, especially autism, was made. Eighteen patients, (11 males, 7 females) aged 8 months to 17 years with OAV were studied. Most frequent systemic malformations included, ear abnormalities (100%), ocular malformations (72%), vertebral deformities (67%), cerebral anomalies (50%), and congenital heart defects (33%). Functional defects consisted of hearing impairment (83%), visual impairment (28%), both visual and hearing impairment (28%), difficulties in feeding/eating (50%), speech (53%), mental retardation (39%), and severe autistic symptoms (11%). Three children were born following assisted fertilization (two intracytoplasmatic sperm injection, one in vitro fertilization), two mothers reported early bleedings, and six (33%) mothers had smoked during pregnancy.

Epidural lornoxicam administration -- innocent

We aimed to determine the analgesic efficacy and clinical or histopathological neurotoxicity of epidural single-dose lornoxicam. Caudal epidural catheters were inserted into 28 rabbits, divided into four groups, on day 1. Pain latency and degree of motor and sensory loss for each animal for different concentrations of lornoxicam were determined on day 2. All animals were sacrificed on day 3 and laminectomy was performed. Five-mum thick sections of spinal cord, obtained from two segments caudal and two segments rostral from tip of the catheter, were fixed and were stained and evaluated by light microscopy. Lornoxicam produced dose-dependent analgesia (increase in pain latency), brief, mild and reversible motor and sensory block, and histopathological signs of neurotoxicity. Clinical application of epidural lornoxicam should proceed with caution.

Ataxic vs painful form of paraneoplastic neuropathy

OBJECTIVE

To characterize the clinicopathologic features of ataxic and painful forms of paraneoplastic neuropathy.

METHODS

Clinical, electrophysiologic, and histopathologic findings were assessed in 17 patients with paraneoplastic neuropathy.

RESULTS

Clinical features can be categorized into two groups: one group (13 patients) with predominantly deep sensory disturbance and a second group (4 patients) with predominantly superficial sensory disturbance. The former group showed severe sensory ataxia and predominantly large myelinated fiber loss in the sural nerve. The latter group showed marked pain, in particular, severe mechanical hyperalgesia, and predominantly small myelinated and unmyelinated fiber loss. Nerve conduction assessment indicated an axonal neuropathy pattern in both groups, while sensory action potentials were more markedly diminished in the sensory ataxic form. Anti-Hu antibodies were detected in half of the patients in both groups. Treatment for cancer was effective to improve or stabilize neuropathic symptoms in some cases from both groups. Immunotherapy was effective only for a short time.

CONCLUSIONS

Paraneoplastic neuropathy can be characterized into two groups by the presence of sensory ataxia or severe spontaneous pain and severe mechanical hyperalgesia. Preferential small myelinated and unmyelinated fiber loss correlated to the cases of severe pain.

Dorsal root ganglionectomy for the diagnosis of sensory neuropathies. Surgical technique and results

BACKGROUND

Inflammatory diseases stand out among sensory neuronopathies because, in their active phase, they can be treated with immunosuppressive agents. Immunosuppressive therapy may present severe adverse effects and requires previous inflammatory activity confirmation. Sensory neuronopathies are diagnosed based on clinical and EMG findings. Diagnostic confirmation and identification of inflammatory activity are based on sensory ganglion histopathological examination. We describe the surgical technique used for dorsal root ganglionectomy in patients with clinical/EMG diagnosis of sensory neuronopathies.

METHODS

The sensory ganglion was obtained from 15 patients through a small T7-T8 hemilaminectomy and foraminotomy to expose the C7 root from its origin to the spinal nerve bifurcation. In 6 patients, the dural cuff supposed to contain the ganglion was resected en bloc; and in 9 patients, the ganglion was obtained through a longitudinal incision of the dural cuff and microsurgical dissection from the ventral and dorsal roots and radicular arteries. All ganglia were histopathologically examined.

RESULTS

No ganglion was found in the dural cuff in 2 patients submitted to en bloc removal, and the ganglion was removed in all patients who underwent microsurgical dissection. All but 2 patients that had ganglion examination presented a neuronopathy of nerve cell loss, 3 with mononuclear inflammatory infiltrate. These patients underwent immunosuppressive therapy, and 2 of them presented clinical improvement. No surgical complications were observed.

CONCLUSIONS

Microsurgical dorsal root ganglionectomy for diagnosing inflammatory sensory ganglionopathies was effective and safe. Although safe, en bloc resection of the proximal dural cuff was not effective for this purpose.

White matter changes in Leber's hereditary optic neuropathy: MRI findings

Leber's hereditary optic neuropathy is a mitochondrial disorder causing bilateral optic nerve degeneration. It is sometimes associated with clinical signs of multiple sclerosis. We report MRI findings in two patients with LHON-MS and comment on possible distinguishing features of this disease entity.

Sphingosine 1-phosphate (S1P) signaling is required for maintenance of hair cells mainly via activation of S1P2

Hearing requires the transduction of vibrational forces by specialized epithelial cells in the cochlea known as hair cells. The human ear contains a finite number of terminally differentiated hair cells that, once lost by noise-induced damage or toxic insult, can never be regenerated. We report here that sphingosine 1-phosphate (S1P) signaling, mainly via activation of its cognate receptor S1P2, is required for the maintenance of vestibular and cochlear hair cells in vivo. Two S1P receptors, S1P2 and S1P3, were found to be expressed in the cochlea by reverse transcription-PCR and in situ hybridization. Mice that are null for both these receptors uniformly display progressive cochlear and vestibular defects with hair cell loss, resulting in complete deafness by 4 weeks of age and, with complete penetrance, balance defects of increasing severity. This study reveals the previously unknown role of S1P signaling in the maintenance of cochlear and vestibular integrity and suggests a means for therapeutic intervention in degenerative hearing loss.

Unexplained neurologic symptoms: An fMRI study of sensory conversion disorder

We investigated three subjects with unexplained sensory loss meeting criteria for conversion disorder using brain fMRI during unilateral and bilateral vibrotactile stimulation. In each subject, stimulation of the affected limb did not produce activation of the contralateral primary somatosensory (S1) region, whereas bilateral limb stimulation did. These findings implicate selective alterations in primary sensorimotor cortex activity in conversion disorder, and may also reconcile the discordant results of previous studies.

Diabetic neuropathy

In this review, an in-depth anatomic and molecular pathogenesis of diabetic neuropathy is provided. Classifications and clinical manifestations of diabetic neuropathy are discussed. The current modalities of treatment and clinical research on this disorder are summarized.

Sensorimotor and cognitive deficits after transient middle cerebral artery occlusion in the mouse

Whereas behavioral impairments after stroke are increasingly studied in the rat, little is known about the long-term functional consequences of focal ischemia in the mouse. To address this issue, Swiss mice underwent transient (60 min) intraluminal occlusion of the middle cerebral artery (MCAo) or sham surgery. Sensorimotor (chimney, accelerating rotarod, pole, corner, adhesive removal and staircase tests) and cognitive (passive avoidance and Morris water maze) performances were regularly assessed during 1 month, after which the final histological lesion was measured. Motor coordination and balance, assessed by the chimney and rotarod tests, were transiently altered by MCAo. Moreover, bradykinesia was evidenced by the pole test. The most striking and long-lasting (1 month) sensorimotor deficits were postural asymmetries on the corner test, bilateral skilled forepaw reaching deficits on the staircase test and a contralateral sensorimotor impairment on the adhesive removal test. MCAo animals showed normal spatial learning abilities on the Morris water maze test, but they displayed learning deficits measured by the passive avoidance test. This latter deficit was significantly correlated with both cortical and striatal damage. Our findings demonstrate the usefulness of three tests that had never been reported in the mouse after ischemia: the adhesive removal, staircase and pole tests, which showed deficits 1 month after ischemia and should therefore constitute meaningful tools in mice for assessing both neuroprotective and regenerative therapies in stroke preclinical studies.

Acute sensory neuronopathy as the presenting symptom of Sjögren’s syndrome

Sensory neuronopathy associated with Sjögren's syndrome (SS) usually has a subacute or chronic onset. We report the case of a 37-year-old woman who presented with an unusual hyperacute form of SS ganglionopathy. She initially developed paresthesias of her fingertips and rapidly became severely ataxic. Nerve conduction studies revealed abnormal sensory but normal motor functions. Lip biopsy showed findings consistent with SS. Sural nerve biopsy showed severe axonal loss. The patient showed modest improvement with immunosuppressive therapies.

Long-term changes of functional MRI-based brain function, behavioral status, and histopathology after transient focal cerebral ischemia in rats

BACKGROUND AND PURPOSE

The relation between recovery of brain function and neurological status after clinical and experimental cerebral ischemia is incompletely characterized. We assessed the evolution of ischemic injury, behavioral status, and brain activity at acute to chronic periods after transient middle cerebral artery occlusion (tMCAO) in rats.

METHODS

Male Sprague-Dawley rats were subjected to 20-minute tMCAO (n=10) or sham operation (n=10). Sensorimotor behavioral testing and multimodal (diffusion, perfusion, T2, and functional) MRI, as well as postmortem hematoxylin-eosin staining, were performed before and up to 21 days after tMCAO. MRI and histological parameters were evaluated in 5 regions of interest within the sensorimotor network. Diffusion, perfusion, and T2 lesion volumes were calculated according to previously established viability thresholds.

RESULTS

Diffusion and perfusion lesions were present during occlusion but disappeared completely and permanently within 30 minutes after reperfusion, with no T2 lesions seen. Functional MRI and behavioral deficits did not normalize until 1 and 21 days after tMCAO, respectively. Histology demonstrated selective neuronal cell death at 7 and 21 days after reperfusion.

CONCLUSIONS

Twenty-minute tMCAO produced distinct changes on multimodal MRI, histology, and behavioral parameters acutely and chronically. Normal findings on MRI after transient ischemia may not indicate normal tissue status, as behavioral and histological anomalies remain. Behavioral dysfunction persisting long after the recovery of MRI parameters may relate to the subtle neuronal damage seen on histology. Together, these results may help explain unremitting neurological deficits in stroke or transient ischemic attack patients with normal MRI findings.

Characteristics of patients with sensory neuropathy diagnosed with abnormal small nerve fibres on skin biopsy

Clinical, laboratory and electrodiagnostic (EDX) characteristics of 62 patients with sensory neuropathy with abnormal skin biopsies were reviewed. Reduced epidermal nerve fibre density (ENFD) was seen in 71% and morphological changes with normal ENFD were seen in 29% of the patients. Patients with small fibre sensory neuropathy may have associated large fibre loss undetected by routine EDX. Identified associations included abnormal glucose metabolism, Lyme vaccination, monoclonal gammopathy, vitamin B12 deficiency, coeliac disease, and diseases of the connective tissue, inflammatory bowel and thyroid. Sensory neuropathy remained undetermined in 50% of the patients.

Ross syndrome: a rare or a misknown disorder of thermoregulation? A skin innervation study on 12 subjects

Ross syndrome is described as a rare disorder of sweating associated with areflexia and tonic pupil. Since Ross's first description in 1958, approximately 40 cases have been described. We assessed the involvement of cutaneous innervation in 12 subjects with Ross syndrome using quantitative sensory testing, sweating assessment and immunohistochemical study of anhidrotic and hyperhidrotic skin. This evaluation was repeated over time in 4 out of 12 subjects. In addition, we enrolled four subjects with Holmes-Adie syndrome (areflexia and tonic pupil) to investigate similarities between the two conditions. We found in Ross patients a complex and progressive involvement of cutaneous sensory and autonomic innervation underlying the impairment of heat production and heat dissipation through both loss of sweating and loss of cutaneous blood flow regulation. In Holmes-Adie subjects we found a mild impairment of sweating without thermoregulatory problems. The persistence of a sudomotor vasoactive intestinal peptide-immunoreactive (VIP-ir) innervation, although deranged and poor, definitely differentiated Holmes-Adie from Ross patients. Ross syndrome is a progressive and complex disorder of thermoregulation difficult to differentiate from the probably pathogenetically related Holmes-Adie syndrome. Sweating assessment and skin biopsy are suitable tools to define a boundary between them. Owing to the large number of Ross patients observed in only 5 years, and to the long and complex medical history of most of them, doubts arise on the effective rarity of this condition, and we warn family doctors and other specialists, besides neurologists, to become aware of this complex disorder.

Oxaliplatin-related neurotoxicity: how and why?

In early clinical trials, oxaliplatin has demonstrated significant activity against colorectal cancer in combination with 5-fluorouracil (5-FU) and folinic acid (FA), both in metastatic as in radically resected disease. The drug differs from the other two most important platinum compounds (cisplatin and carboplatin) for the absence of nephrotoxicity or for the reduced drug-induced ototoxicity. During its administration, two different types of neurological symptoms can be experienced: the first one occurs during or immediately after the end of the infusion and it appears as a transient peripheral sensory neuropathy manifesting as paresthesias and dysesthesia in the extremities sometimes accompanied by muscular contractions of the extremities or the jaw (triggered or enhanced by exposure to cold). The second one occurs after long-term administration of oxaliplatin presenting with deep sensory loss, sensory ataxia and functional impairment (similar to those observed with cisplatin). This type of neurotoxicity is usually late-onset and correlated with the cumulative-dose of oxaliplatin. The aim of this review is to analyse the mechanism underlying induction of neurotoxicity and the possible treatments to prevent and to treat it.

Sensory neuropathy in human immunodeficiency virus/acquired immunodeficiency syndrome patients: protease inhibitor-mediated neurotoxicity

OBJECTIVE

Human immunodeficiency virus-associated sensory neuropathy (HIV-SN) is a common and disabling disorder, often associated with antiretroviral therapy (ART) use. We investigated the clinical features and associated pathogenic determinants of HIV-SN in a neurological cohort of HIV-infected patients, together with a novel model of HIV-SN.

METHODS

HIV-infected patients with neurological disease were investigated in terms of clinical and laboratory aspects together with ART exposure focusing on symptomatic HIV-SN. Rat-derived dorsal root ganglion (DRG) cultures, transgenic for human CD4 and CCR5 treated with ARTs or HIV infected, or both, were studied with respect to quantitative neuronal injury.

RESULTS

Among 221 patients assessed from 1998 to 2004, 120 had no sensory neuropathy, whereas 101 displayed HIV-SN, including 64 with distal sensory neuropathy and 37 with antiretroviral toxic neuropathy. HIV-SN patients exhibited significantly greater mean age, peak plasma viral loads, and exposure to neurotoxic dideoxynucleosides and protease inhibitors, including indinavir, saquinavir, or ritonavir. HIV-infected DRG cultures exposed to indinavir or didanosine showed significant neuronal atrophy, neurite retraction, and process loss, compared with controls. Indinavir was selectively cytotoxic to DRG macrophages compared with other ARTs.

INTERPRETATION

Protease inhibitor exposure is an unrecognized risk factor for the development of HIV-SN, which may potentiate neuronal damage in HIV-infected DRGs, possibly through the loss of macrophage-derived trophic factors.

Chronic progressive sensory ataxic neuropathy associated with limited systemic sclerosis

We report the case of a 33-year-old woman with limited systemic sclerosis and chronic progressive sensory ataxic neuropathy. Sural nerve biopsy showed loss of myelinated fibers mostly those of large diameter, axonal degeneration and infiltration of macrophages, but no signs of vasculitis. Physical examination, laboratory testing, neurophysiological and neuroradiological examinations suggested that the dorsal root was primarily affected in this patient. Cytokine analysis by multiplex bead array assay revealed that IL-1beta and GM-CSF were increased both in serum and CSF. Although her symptoms did not respond to corticosteroid therapy, intravenous immunoglobulin (IVIg) therapy resulted in marked improvement. IVIg could be effective in case of immune-mediated reversible neuronal dysfunction associated with collagen disease without vasculitis.

Spinocerebellar ataxia type 4 (SCA4): Initial pathoanatomical study reveals widespread cerebellar and brainstem degeneration

Spinocerebellar ataxia type 4 (SCA4), also known as 'hereditary ataxia with sensory neuropathy', represents a very rare, progressive and untreatable form of an autosomal dominant inherited cerebellar ataxia (ADCA). Due to a lack of autopsy cases, no neuropathological or clinicopathological studies had yet been performed in SCA4. In the present study, the first available cerebellar and brainstem tissue of a clinically diagnosed and genetically-confirmed German SCA4 patient was pathoanatomically studied using serial thick sections. During this systematic postmortem investigation, along with an obvious demyelinization of cerebellar and brainstem fiber tracts we observed widespread cerebellar and brainstem neurodegeneration with marked neuronal loss in the substantia nigra and ventral tegmental area, central raphe and pontine nuclei, all auditory brainstem nuclei, in the abducens, principal trigeminal, spinal trigeminal, facial, superior vestibular, medial vestibular, interstitial vestibular, dorsal motor vagal, hypoglossal, and prepositus hypoglossal nuclei, as well as in the nucleus raphe interpositus, all dorsal column nuclei, and in the principal and medial subnuclei of the inferior olive. Severe neuronal loss was seen in the Purkinje cell layer of the cerebellum, in the cerebellar fastigial nucleus, in the red, trochlear, lateral vestibular, and lateral reticular nuclei, the reticulotegmental nucleus of the pons, and the nucleus of Roller. In addition, immunocytochemical analysis using the anti-polyglutamine antibody 1C2 failed to detect any polyglutamine-related immunoreactivity in the central nervous regions of this SCA4 patient studied. In view of the known functional role of affected nuclei and related fiber tracts, the present findings not only offer explanations for the well-known disease symptoms of SCA4 patients (i.e. ataxic symptoms, dysarthria and somatosensory deficits), but for the first time help to explain why diplopia, gaze-evoked nystagmus, auditory impairments and pathologically altered brainstem auditory evoked potentials, saccadic smooth pursuits, impaired somatosensory functions in the face, and dysphagia may occur during the course of SCA4. Finally, the results of our immunocytochemical studies support the concept that SCA4 is not a member of the CAG-repeat or polyglutamine diseases.

Persistent motor deficit following infusion of autologous blood into the periventricular region of neonatal rats

Periventricular hemorrhage (PVH) in the brain of premature infants is often associated with developmental delay and persistent motor deficits. Our goal is to develop a rodent model that mimics the behavioral phenotype. We hypothesized that autologous blood infusion into the periventricular germinal matrix region of neonatal rats would lead to immediate and long-term behavioral changes. Tail blood or saline was infused into the periventricular region of 1-day-old rats. Magnetic resonance (MR) imaging was used to demonstrate the hematoma. Rats with blood infusion, as well as saline and intact controls, underwent behavior tests until 10 weeks age. Blood-infused rats displayed significant delay in motor development (ambulation, righting response, and negative geotaxis) to 22 days of age. As young adults, they exhibited impaired ability to stay on a rotating rod and to reach for food pellets. MR imaging at 10 weeks demonstrated subsets of rats with normal appearing brains, focal cortical infarcts, or mild hydrocephalus. There was a good correlation between MR imaging and histological findings. Some rats exhibited periventricular heterotopia and/or subtle striatal abnormalities not apparent on MR images. We conclude that autologous blood infusion into the brain of neonatal rats successfully models some aspects of periventricular hemorrhage that occurs after premature birth in humans.

Sensory nerve-dominant nerve degeneration and remodeling in the mutant mice lacking complex gangliosides

Gangliosides, sialic acid-containing glycosphingo-lipids, are enriched in the mammalian nervous system. Since mutant mice with disrupted beta1,4-N-acetylgalactosaminyl-transferase (GM2/GD2 synthase) were generated, there have been several studies on the pathology of the mutant mice, i.e. mild functional disorders and Wallerian degeneration in the peripheral nervous system. To further analyze the chronological alteration in the mutant mice, we examined the peripheral and CNS mainly with morphological approaches, such as electron microscopy and immunohistochemistry. Accordingly with the sensory dysfunction, neural degeneration, glial proliferation and synaptic remodeling in the dorsal horn of the spinal cord were found in adult mice. Thick astrocytic processes with densely packed glial filaments were extended among the neuropils and around blood vessels. Morphological changes in the synaptic vesicles and modes of synaptic contacts with central terminals were detected, suggesting synaptic remodeling following the degeneration. These results suggest that complex gangliosides are essential in the maintenance of integrity in architecture and function of the nervous system, lack of which results in neural degeneration in a sensory nerve-dominant manner.

The wide spectrum of clinical manifestations in Sjögren's syndrome-associated neuropathy

We assessed the clinicopathological features of 92 patients with primary Sjögren's syndrome-associated neuropathy (76 women, 16 men, 54.7 years, age at onset). The majority of patients (93%) were diagnosed with Sjögren's syndrome after neuropathic symptoms appeared. We classified these patients into seven forms of neuropathy: sensory ataxic neuropathy (n = 36), painful sensory neuropathy without sensory ataxia (n = 18), multiple mononeuropathy (n = 11), multiple cranial neuropathy (n = 5), trigeminal neuropathy (n = 15), autonomic neuropathy (n = 3) and radiculoneuropathy (n = 4), based on the predominant neuropathic symptoms. Acute or subacute onset was seen more frequently in multiple mononeuropathy and multiple cranial neuropathy, whereas chronic progression was predominant in other forms of neuropathy. Sensory symptoms without substantial motor involvement were seen predominantly in sensory ataxic, painful sensory, trigeminal and autonomic neuropathy, although the affected sensory modalities and distribution pattern varied. In contrast, motor weakness and muscle atrophy were observed in multiple mononeuropathy, multiple cranial neuropathy and radiculoneuropathy. Autonomic symptoms were often seen in all forms of neuropathy. Abnormal pupils and orthostatic hypotension were particularly frequent in sensory ataxic, painful, trigeminal and autonomic neuropathy. Unelicited somatosensory evoked potentials and spinal cord posterior column abnormalities in MRI were observed in sensory ataxic, painful and autonomic neuropathy. Sural nerve biopsy specimens (n = 55) revealed variable degrees of axon loss. Predominantly large fibre loss was observed in sensory ataxic neuropathy, whereas predominantly small fibre loss occurred in painful sensory neuropathy. Angiitis and perivascular cell invasion were seen most frequently in multiple mononeuropathy, followed by sensory ataxic neuropathy. The autopsy findings of one patient with sensory ataxic neuropathy showed severe large sensory neuron loss paralleling to dorsal root and posterior column involvement of the spinal cord, and severe sympathetic neuron loss. Degrees of neuron loss in the dorsal and sympathetic ganglion corresponded to segmental distribution of sensory and sweating impairment. Multifocal T-cell invasion was seen in the dorsal root and sympathetic ganglion, perineurial space and vessel walls in the nerve trunks. Differential therapeutic responses for corticosteroids and IVIg were seen among the neuropathic forms. These clinicopathological observations suggest that sensory ataxic, painful and perhaps trigeminal neuropathy are related to ganglioneuronopathic process, whereas multiple mononeuropathy and multiple cranial neuropathy would be more closely associated with vasculitic process.

Motor cortex excitability after thalamic infarction

OBJECTIVE

We examined 8 patients with hemihypesthesia due to an ischemic thalamic lesion to explore the effects of a central sensory dysfunction on motor cortex excitability.

METHODS

Motor excitability was assessed using transcranial magnetic stimulation techniques and electrical peripheral nerve stimulation. Motor function was evaluated by the Nine-Hole-Peg Test and measurement of hand grip strength. The affected side was compared with the non-lesioned side and with an age-matched control group.

RESULTS

Patients had a loss of inhibition and an increase of facilitation in the motor cortex of the affected side. The silent period was prolonged and motor function was impaired on the affected side.

CONCLUSIONS

A thalamic lesion can modulate motor cortical excitability.

SIGNIFICANCE

This study suggests that, under normal conditions, somatosensory afferents influence inhibitory and excitatory properties in the motor cortex.

Preattentive interference between touch and audition: a case study on multisensory alloesthesia

Alloesthesia is a rare clinical condition that corresponds to a spatial disorder of stimulus localization, in which patients experience a given stimulus on the side opposite to the side of stimulation. Whereas it has been mostly described for unisensory stimulations, evidence of multisensory alloesthesia is only anecdotal. Here, we investigated a case of multisensory auditory-tactile alloesthesia. Our data suggest that auditory-tactile integration and multisensory alloesthesia not only depend on attentional mechanisms, but also on somatotopic preattentive mechanisms.

Primary AL (kappa-light chain) amyloidosis manifesting as peripheral neuropathy in a young male without increase in serum and urine immunoglobulin load: a diagnostic challenge

Primary systemic or AL amyloidosis is a multisystem disorder characterized by diffuse extracellular infiltration of a fibrillar protein of monoclonal light chain origin (AL). Majority of the patients have monoclonal immunoglobulin in serum and/or urine and some have clonal proliferation of plasma cells in their bone marrow. This disease has the widest spectrum of organ involvement, most commonly affecting the kidneys, heart and liver. Involvement of peripheral nervous system is not infrequent and may be the presenting feature of the disease process. Thus, recognition of peripheral neuropathy and affecting the kidney as an early symptom of AL amyloidosis may widen the scope for therapeutic intervention. We describe here a rare case of primary amyloidosis (AL) kappa-light chain presenting with clinical features of peripheral neuropathy and affecting the kidney and heart at an early age of 18 years, hitherto unreported in literature. The case was further interesting as it was not associated with increased serum/urine immunoglobulins or plasma cells in bone marrow. Diagnosis was confirmed using immuno-electron microscopy on sural nerve biopsy.

Sensory neuropathy in vasculitis: a clinical, pathologic, and electrophysiologic study

BACKGROUND

Vasculitis is not usually considered as a cause of symmetric sensory neuropathy.

OBJECTIVE AND METHODS

To present the clinical, pathologic, and electrophysiologic features of 17 (16%) cases of sensory neuropathy in vasculitis (SNV) among 106 cases with histologically proven vasculitic neuropathy that were collected over the last 30 years.

RESULTS

In 41% of cases, SNV was found as systemic vasculitic neuropathy in association with primary vasculitic disease. The most common clinical presentation was symmetric polyneuropathy, seen in 53% of cases. The most common nerve conduction pattern was diffuse neuropathy pattern of axonal degeneration. Sural nerve biopsy was diagnostic in 88% of cases. In two cases, muscle biopsy was necessary for the definite diagnosis of vasculitis. Non-systemic SNV is usually benign. Of 11 patients followed for longer than 2 years, none developed motor weakness due to neuropathy.

CONCLUSION

Sensory neuropathy, regardless of symmetry, can be due to vasculitis.

Characterization of a rat model to study acute neuroinflammation on histopathological, biochemical and functional outcomes

Neuroinflammation is one of the events occurring after acute brain injuries. The aim of the present report was to characterize a rat model to study acute neuroinflammation on the histopathological, biochemical and functional outcomes. Lipopolysaccharide (LPS), known as a strong immunostimulant, was directly injected into the hippocampus. The spatiotemporal evolution of inducible NOS (iNOS) and cell death was studied from 6 h to 7 days. A perfect time course correlation was observed between iNOS immunoreactivity and iNOS activity showing an acute, expansive and transient iNOS induction in the hippocampus with a peak at 24 h. It was associated with a marked increase in NO metabolite (NO(x)) levels, and a high level of myeloperoxidase (MPO) activity. This inflammation precedes a massive cellular loss including at least neurons and astrocytes, and a drop of constitutive NOS activity, restrictive to the ipsilateral hippocampus from 48 h after LPS injection. Moreover, sensorimotor function impairment occurred from 24 h to 7 days with a maximum at 24 h post-LPS injection. Therefore, we characterized an in vivo model of acute neuroinflammation and neurodegeneration, in relation with a neurological deficit, which may be a powerful tool for mechanistic studies and for further evaluation of the potential neuroprotective agents.

Pyridoxine-induced toxicity in rats: a stereological quantification of the sensory neuropathy

Excess ingestion of pyridoxine (vitamin B6) causes a severe sensory neuropathy in humans. The mechanism of action has not been fully elucidated, and studies of pyridoxine neuropathy in experimental animals have yielded disparate results. Pyridoxine intoxication appears to produce a neuropathy characterized by necrosis of dorsal root ganglion (DRG) sensory neurons and degeneration of peripheral and central sensory projections, with large diameter neurons being particularly affected. The major determinants affecting the severity of the pyridoxine neuropathy appear to be duration and dose of pyridoxine administration, differential neuronal vulnerability, and species susceptibility. The present study used design-based stereological techniques in conjunction with electrophysiological measures to quantify the morphological and physiological changes that occur in the DRG and the distal myelinated axons of the sciatic nerve following pyridoxine intoxication. This combined stereological and electrophysiological method demonstrates a general approach that could be used for assessing the correlation between pathophysiological and functional parameters in animal models of toxic neuropathy.