Treatment patterns and costs among patients with OAB treated with combination oral therapy, sacral nerve stimulation, percutaneous tibial nerve stimulation, or onabotulinumtoxinA in the United States.

INTRODUCTION: Treatment patterns and costs were characterized among patients with overactive bladder (OAB) receiving later-line target therapies (combination mirabegron/antimuscarinic, sacral nerve stimulation [SNS], percutaneous tibial nerve stimulation [PTNS], or onabotulinumtoxinA). METHODS: In a retrospective cohort study using 2013 to 2017 MarketScan databases, two partially overlapping cohorts of adults with OAB ("IPT cohort": patients with incident OAB pharmacotherapy use; "ITT cohort," incident target therapy) with continuous enrollment were identified; first use was index. Demographic characteristics, treatment patterns and costs over the 24-month follow-up period were summarized. Crude mean (standard deviation [SD]) OAB-specific (assessed by OAB diagnostic code or pharmaceutical dispensation record) costs were estimated according to target therapy. RESULTS: The IPT cohort comprised 54 066 individuals (mean [SD] age 58.5 [15.0] years; 76% female), the ITT cohort, 1662 individuals (mean [SD] age 62.8 [14.9] years; 83% female). Seventeen percent of the IPT cohort were treated with subsequent line(s) of therapy after index therapy; among those, 73% received antimuscarinics, 23% mirabegron, and 1.4% a target therapy. For the ITT cohort, 32% were initially treated with SNS, 27% with onabotulinumtoxinA, 26% with combination mirabegron/antimuscarinic, and 15% with PTNS. Subsequently, one-third of this cohort received additional therapies. Mean (SD) costs were lowest among patients receiving index therapy PTNS ($6959 [$7533]) and highest for SNS ($29 702 [$26 802]). CONCLUSIONS: Costs for SNS over 24 months are substantially higher than other treatments. A treatment patterns analysis indicates that oral therapies predominate; first-line combination therapy is common in the ITT cohort and uptake of oral therapy after procedural options is substantial.

Contemporary Patterns of Third-line Treatments for Privately Insured Individuals With Overactive Bladder in the United States.

OBJECTIVE: To evaluate utilization of third-line overactive bladder (OAB) treatments including percutaneous tibial nerve stimulation (PTNS), sacral nerve stimulation (SNS), and intradetrusor botulinum toxin A (BTX) among privately insured patients and examine factors associated with their use. MATERIALS AND METHODS: Using MarketScan claims (2015-2017), we identified patients who underwent third-line OAB treatments based on procedure codes. Factors of interest included location, age, health plan, among others. We fit multivariable logistic regression models to estimate associations between pertinent factors with receipt of PTNS and SNS relative to BTX and associations between provider type and practice location with each treatment modality. RESULTS: We identified 7383 patients (mean age 50.9) in our cohort. SNS was used most frequently (n = 3602, 48.8%), while PTNS was used least frequently (n = 955, 12.9%). PTNS patients were more likely to reside in metropolitan areas (vs BTX: OR 1.6, 95%CI 1.3-2.1; vs SNS: OR 2.2, 95%CI 1.7-2.8), be aged 55 years or older (vs BTX: 54% vs 47%, OR 1.6, 95%CI 1.2-2.1; vs SNS: 54% vs 45%, OR 1.6, 95%CI 1.2-2.0), and be covered under a health maintenance organization (vs BTX: 17% vs 10%; vs SNS: 17% vs 10%, P <.01). Urologists were most likely to perform SNS, and gynecologists were most likely to perform BTX. 91% of PTNS procedures were performed in office settings. CONCLUSION: Among patients receiving third-line OAB treatment, PTNS was used infrequently. PTNS utilization was concentrated within urban areas, and among older patients and those covered by cost-conscious health maintenance organizations.

Sonographic assessment of nerve blood flow in diabetic neuropathy.

AIMS: To undertake sonographic assessment of nerve blood flow in people with Type 2 diabetes and correlate the findings with neuropathy severity scores and electrophysiological measurements. METHODS: Median and tibial nerve ultrasound scans were undertaken in 75 people with diabetes and 30 aged-matched controls without diabetes, using a high-resolution linear probe at non-entrapment sites. Nerve blood flow was quantified using power Doppler techniques to obtain the vessel score and the maximum perfusion intensity. Neuropathy severity was assessed using a total neuropathy score. RESULTS: Diabetic nerves had higher rates of nerve blood flow detection (28%) compared to the control group (P < 0.0001). Significant correlations were found between nerve blood flow measurements and nerve size (P <0.001), reported sensory symptoms (P < 0.05) and neuropathy severity scores (P < 0.001). The cohort with diabetes had significantly larger median (8.5 ± 0.3 mm2 vs 7.2 ± 0.1 mm2 ; P < 0.05) and tibial nerves (18.0 ± 0.9 mm2 vs 12.8 ± 0.5 mm2 ; P < 0.05) compared with controls. CONCLUSION: Peripheral nerve hypervascularity is detectable by ultrasonography in moderate to severe diabetic neuropathy with prominent sensory dysfunction.

Assessment of Peripheral Nerves With Shear Wave Elastography in Type 1 Diabetic Adolescents Without Diabetic Peripheral Neuropathy.

OBJECTIVES: To investigate the utility of shear wave elastography (SWE) in detecting morphologic abnormalities of the median nerve and posterior tibial nerve in transverse and longitudinal axes in adolescents with type 1 diabetes mellitus (DM) without diabetic peripheral neuropathy (DPN). METHODS: The median nerves and posterior tibial nerves of 25 adolescents with diagnosis and follow-up of type 1 DM without DPN and 32 healthy volunteers were evaluated with SWE by 2 observers on the transverse and longitudinal axes. The cross-sectional area and thickness of the nerves and disease duration were noted, and probable associations of these parameters with SWE features were analyzed. Interobserver and intraobserver correlations were also examined. The statistical significance level was set at P < .05. RESULTS: Both the median nerve and posterior tibial nerve were smaller, thinner, and stiffer in the patient group for both observers on both axes. The disease duration weakly correlated with median nerve SWE features (r = 0.245-0391). The thickness and cross-sectional area had no correlations with SWE features. CONCLUSIONS: The median nerve and posterior tibial nerve in adolescents with type 1 DM without DPN have morphologic abnormalities that can be displayed by SWE regardless of the imaging axis. Shear wave elastography may have a potential role in subclinical DPN, but the reliability of the findings is not as high as desirable.

Electrophysiological Assessment and Classification of Motor Pathway Function in Patients With Spinal Dural Arteriovenous Fistula.

PURPOSE: The diagnosis of spinal dural arteriovenous fistula (SDAVF) is difficult and often delayed because clinical features are often nonspecific. We assessed the motor function electrophysiologically in patients with SDAVF. METHODS: Motor-evoked potentials after transcranial magnetic stimulation and compound muscle action potentials and F-waves after electrical stimulation in the ulnar and tibial nerves were measured from the abductor hallucis (AH) muscles in 14 patients with SDAVF (SDAVF group), 12 patients with compressive thoracic myelopathy (CTM group), and 16 normal subjects (control group). The peripheral conduction time determined from abductor hallucis muscles (PCT-AH) and the central motor conduction time determined from abductor hallucis muscles (CMCT-AH) were calculated. According to the neurological findings, patients in the SDAVF group were classified to upper motor neuron (UMN) sign and lower motor neuron (LMN) sign categories. RESULTS: CMCT-AH in the SDAVF and CMT groups were significantly longer than those in the control group. PCT-AH in the SDAVF group was significantly longer than that in the control and CMT groups. Twelve patients in the SDAVF group showed abnormal CMCT-AH and/or PCT-AH. Abnormal CMCT-AH and PCT-AH were detected in five cases that exhibited UMN sign and/or LMN sign. Three cases with abnormal CMCT-AH and normal PCT-AH exhibited UMN sign. LMN sign without UMN sign was observed in four cases with abnormal PCT-AH and normal CMCT-AH. CONCLUSIONS: Our study revealed abnormalities in the corticospinal tract and/or lower motor neurons, and classified the patients with SDAVF into three types: the UMN type, LMN type, and mixed type.

Posterior tibial nerve stimulation for fecal incontinence: where are we?

Neurostimulation remains the mainstay of treatment for patients with faecal incontinence who fails to respond to available conservative measures. Sacral nerve stimulation (SNS) is the main form of neurostimulation that is in use today. Posterior tibial nerve stimulation (PTNS)--both the percutaneous and the transcutaneous routes--remains a relatively new entry in neurostimulation. Though in its infancy, PTNS holds promise to be an effective, patient friendly, safe and cheap treatment. However, presently PTNS only appears to have a minor role with SNS having the limelight in treating patients with faecal incontinence. This seems to have arisen as the strong, uniform and evidence based data on SNS remains to have been unchallenged yet by the weak, disjointed and unsupported evidence for both percutaneous and transcutaneous PTNS. The use of PTNS is slowly gaining acceptance. However, several questions remain unanswered in the delivery of PTNS. These have raised dilemmas which as long as they remain unsolved can considerably weaken the argument that PTNS could offer a viable alternative to SNS. This paper reviews available information on PTNS and focuses on these dilemmas in the light of existing evidence.

A comparison of the change in clinical severity scale score and a retrospective physician assessment of neurological outcome in individuals with leprosy associated nerve function impairment after treatment with corticosteroids.

OBJECTIVES: To determine whether the measured change in score of a validated clinical severity scale reflected physician assessed improvement in individuals who had received corticosteroid therapy for leprosy associated nerve damage. DESIGN: Patients with nerve function impairment who participated in a randomised controlled trial of corticosteroids were classified into two groups using a retrospectively determined physician assessment of improvement. One group consisted of patients who had recovered or improved the other of patients who were unchanged or had deteriorated. The change in the clinical severity scale scores of these two groups was compared. RESULTS: The change in the clinical severity scale scores of the 34 eligible individuals in the two groups were significantly different (P = 0.003). Individuals in the group who recovered or improved had a greater change in severity score than those whose nerve function was unchanged or deteriorated. CONCLUSION: The scale for measuring the severity of leprosy Type 1 reactions (T1Rs) and/or nerve function impairment reflects the clinical improvement of individuals with leprosy associated nerve damage.

Assessment of the medial dorsal cutaneous, dorsal sural, and medial plantar nerves in impaired glucose tolerance and diabetic patients with normal sural and superficial peroneal nerve responses.

OBJECTIVE: This study evaluated the nerve conduction study (NCS) parameters of the most distal sensory nerves of the lower extremities-namely, the medial dorsal cutaneous (MDC), dorsal sural (DS), and medial plantar (MP) nerves-in diabetic (DM) and impaired glucose tolerance (IGT) patients who displayed normal findings on their routine NCSs. RESEARCH DESIGN AND METHODS: Standard NCSs were performed on healthy control (HC), DM, and IGT groups (N = 147). The bilateral NCS parameters of the MDC, DS, and MP nerves were investigated. The Toronto Clinical Scoring System (TCSS) was assessed for the DM and IGT groups. RESULTS: The mean TCSS scores of the IGT and DM groups were 2.5 ± 2.3 and 2.8 ± 2.2, respectively. No significant differences between the two groups were observed. After adjustment of age and BMI, the DM group showed significant NCS differences in DS and MDC nerves compared with the HC group (P < 0.05). These differences were also exhibited in the left DS of the IGT group (P = 0.0003). More advanced NCS findings were observed in the DM group. Bilateral abnormal NCS responses in these distal sensory nerves were found in 40 and 16% of DM and IGT patients, respectively. CONCLUSIONS: These results showed that the simultaneous assessment of the most distal sensory nerves allowed the detection of early NCS changes in the IGT and DM groups, even when the routine NCS showed normal findings.

Neurophysiological assessment of spinal cord stimulation in failed back surgery syndrome.

Despite good clinical results, the mechanisms of action of spinal cord stimulation (SCS) for the treatment of chronic refractory neuropathic pain have not yet been elucidated. In the present study, the effects of SCS were assessed on various neurophysiological parameters in a series of 20 patients, successfully treated by SCS for mostly unilateral, drug-resistant lower limb pain due to failed back surgery syndrome. Plantar sympathetic skin response (SSR), F-wave and somatosensory-evoked potentials (P40-SEP) to tibial nerve stimulation, H-reflex of soleus muscle, and nociceptive flexion (RIII) reflex to sural nerve stimulation were recorded at the painful lower limb. The study included two recording sets while SCS was switched 'ON' or 'OFF' for 1h. Significant changes in 'ON' condition were as follows: SSR amplitude, H-reflex threshold, and RIII-reflex threshold and latency were increased, whereas SSR latency, F-wave latency, H-reflex amplitude, P40-SEP amplitude, and RIII-reflex area were reduced. Analgesia induced by SCS mainly correlated with RIII attenuation, supporting a real analgesic efficacy of the procedure. This study showed that SCS is able to inhibit both nociceptive (RIII-reflex) and non-nociceptive (P40-SEP, H-reflex) myelinated sensory afferents at segmental spinal or supraspinal level, and to increase cholinergic sympathetic skin activities (SSR facilitation). Complex modulating effects can be produced by SCS on various neural circuits, including a broad inhibition of both noxious and innocuous sensory information processing.

Cutaneous silent periods in the assessment of mild cervical spondylotic myelopathy.

STUDY DESIGN: Clinical, neuroradiologic, and neurophysiologic description of 21 patients with compressive cervical spondylotic myelopathy (CCSM). OBJECTIVE: To describe the utility of cutaneous silent periods (CSPs) for functional evaluation of mild CCSM. SUMMARY OF BACKGROUND DATA: Electroneurography, electromyography, and somatosensory and motor evoked potentials (SEPs, MEPs) are routinely used for comprehensive functional neurophysiological evaluation of CCSM. CSPs have been reported in various intramedullary spinal cord lesions, however, they have not been systematically studied in mild CCSM. METHODS: We investigated 21 patients with multilevel CCSM as documented by magnetic resonance imaging. We recorded CSPs in thenar muscles after noxious digit II stimulation and compared them with median and tibial nerve SEPs and MEPs obtained from abductor digiti minimi and tibialis anterior muscles. Electroneurography and electromyography were obtained in affected myotomes. RESULTS: CSP onset and end latencies were delayed, and CSP duration was shortened, in CCSM patients. CSP abnormalities were present in 17 patients of whom all, but 1 presented with intramedullary magnetic resonance imaging hyperintensity. All 11 limbs affected by hypalgesia and thermhypesthesia had abnormal CSPs, whereas no spinothalamic deficit was noted in any limb with normal CSPs. CSP onset latency was inversely correlated with JOA score and N13 amplitude, and was positively correlated with central motor conduction time to abductor digiti minimi. CSP duration was inversely correlated with central motor conduction time to tibialis anterior. Electromyographic abnormalities were found in 7 patients. CONCLUSION: We confirm the value of neurophysiological evaluation of CCSM. MEPs were more frequently abnormal than SEPs. CSP abnormalities were almost equally sensitive as upper limb MEPs, and were highly associated with spinothalamic dysfunction. The high correlation of CSP abnormalities with corticospinal tract dysfunction suggests supraspinal influence on CSPs. Our findings corroborate the utility of CSP testing in the comprehensive assessment of intramedullary spinal cord dysfunction in CCSM.

Role of timing in assessment of nerve regeneration.

Small animal models are indispensable for research on nerve injury and reconstruction, but their superlative regenerative potential may confound experimental interpretation. This study investigated time-dependent neuroregenerative phenomena in rodents. Forty-six Lewis rats were randomized to three nerve allograft groups treated with 2 mg/(kg day) tacrolimus; 5 mg/(kg day) Cyclosporine A; or placebo injection. Nerves were subjected to histomorphometric and walking track analysis at serial time points. Tacrolimus increased fiber density, percent neural tissue, and nerve fiber count and accelerated functional recovery at 40 days, but these differences were undetectable by 70 days. Serial walking track analysis showed a similar pattern of recovery. A "blow-through" effect is observed in rodents whereby an advancing nerve front overcomes an experimental defect given sufficient time, rendering experimental groups indistinguishable at late time points. Selection of validated time points and corroboration in higher animal models are essential prerequisites for the clinical application of basic research on nerve regeneration.

Two-dimensional digital video ankle motion analysis for assessment of function in the rat sciatic nerve model.

Ankle motion analysis may provide a better method to assess function in the rat sciatic nerve model than the standard method, the sciatic functional index (SFI), but it is not widely used in experiments on nerve regeneration possibly because of complicated analysis. In this study, we investigated the practical use of a two-dimensional (2D) digital video motion analysis system. Reproducibility was investigated in normal rats. Recovery of ankle motion was analyzed after sciatic, tibial, and peroneal nerve crush injury. Results were compared with scores for the SFI. Results were not significantly different from animal-to-animal and day-to-day. Interobserver variability also was small. In the analysis of recovery after separate nerve crush injuries, subtle differences in ankle plantar flexion and dorsiflexion could be detected. The method was also more sensitive than the SFI: whereas scores for the SFI had returned to normal 4 weeks after sciatic nerve crush injury, the ankle angle at mid-stance was still significantly different from that in sham-operated animals 6 weeks after the injury. 2D digital video ankle motion analysis is a practical and sensitive method to assess function in the rat sciatic nerve model.

Lumbar spinal stenosis: assessment of cauda equina involvement by electrophysiological recordings.

UNLABELLED: The objective of this study was to investigate the relationship between electrophysiological recordings and clinical as well as radiological findings in patients suggestive to suffer from a lumbar spinal stenosis (LSS). We hypothesise that the electrophysiological recordings, especially SSEP, indicate a lumbar nerve involvement that is complementary to the neurological examination and can provide confirmatory information in less obvious clinical cases. In a prospective cohort study, 54 patients scheduled for surgery due to LSS were enrolled in an unmasked, uncontrolled trial. All patients were assessed by neurological examination, electrophysiological recordings, and magnetic resonance imaging (MRI) of the lumbar spine. The electrophysiological recordings focused on spinal lumbar nerve involvement. RESULTS: About 88% suffered from a multisegmental LSS and 91% of patients respectively complained of chronic lower back pain and/or leg pain for more than 3 months, combined with a restriction in walking distance. The neurological examination revealed only a few patients with sensory and/or motor deficits while 87% of patients showed pathological electrophysiological recordings (abnormal tibial SSEP in 78% of patients, abnormal H-reflex in 52% of patients). CONCLUSIONS: Whereas the clinical examination, even in severe LSS, showed no specific sensory-motor deficit, the electrophysiological recordings indicated that the majority of patients had a neurogenic disorder within the lumbar spine. By the pattern of bilateral pathological tibial SSEP and pathological reflexes associated with normal peripheral nerve conduction, LSS can be separated from a demyelinating polyneuropathy and mono-radiculopathy. The applied electrophysiological recordings, especially SSEP, can confirm a neurogenic claudication due to cauda equina involvement and help to differentiate neurogenic from vascular claudication or musculo-skeletal disorders of the lower limbs. Therefore, electro-physiological recordings provide additional information to the neurological examination when the clinical relevance of a radiologically-suspected LSS needs to be confirmed.

Assessment of somatosensory evoked potentials during resuscitation of a 15-year-old boy with Duchenne muscular dystrophy.

Patients with Duchenne muscular dystrophy (DMD) are likely to suffer from cardiac insufficiency. Subclinical cardiac insufficiency may decompensate intraoperatively. During spinal surgery, recording of somatosensory evoked potentials (SSEP) is the standard method of spinal cord monitoring. Assessment of SSEP has proven to be a highly prognostic measure of neurological outcome after cardiopulmonary resuscitation (CPR). In the case presented, scalp SSEP as response to stimulation of both median and tibial nerves were recorded during spinal surgery in a 15-year-old boy with DMD. The patient developed severe hypotension and circulatory collapse intraoperatively. SSEP were measured before, during and up to 3h after circulatory collapse. He was successfully resuscitated and fully recovered. Latencies of SSEP remained stable from all extremities whereas amplitudes significantly decreased during CPR, but recovered completely within 3h. The amplitudes of SSEP serve as a more sensitive marker for brain ischaemia than latencies. Stability of latencies and full recovery of amplitudes within 3h indicated sufficient CPR and predicted a good neurological recovery.

Assessment of recovery following a novel partial nerve lesion in a rat model.

Partial nerve lesions with a varying degree of retained function and often a painful neuroma pose a dilemma for the clinician. Surgical treatment of partial nerve lesion is perilous because of possible damage to intact axons and subsequent loss of retained function. We present a new rat model of a partial nerve lesion, allowing further study to improve treatment for this condition. A partial (50%) lesion of the tibial portion of the rat sciatic nerve was created and compared to standard crush and neurectomy control lesions. The extent of lost function and the progress of postoperative recovery following the three lesions were compared using serial walking track analyses and end-point muscle weight ratios for atrophy as outcome measures. All groups had tibial functional indices (TFI) significantly different from one another after 1 week. TFIs for the crush group returned to normal by 4 weeks, whereas the neurectomy group showed no recovery. The partial lesion group gradually improved, reaching a plateau of 44% by 7 weeks. Gastrocnemius muscle weight ratios for the partial, crush, and neurectomy lesions at 9 weeks were 0.63, 0.87, and 0.32, respectively. There was a strong correlation between the TFI and muscle weight ratios (r(2) = 0.89; P < 0.001) suggesting that these outcome measures are highly predictive of function. In conclusion, the partial lesion showed a gradual but incomplete functional recovery with a complementary degree of muscle atrophy. The model may prove useful in the evaluation of proposed treatments for partial nerve lesions and the associated painful state.

Mononeuropathy multiplex in hemophilia: an electrophysiologic assessment.

Single nerve lesion or mononeuropathy caused by extrinsic compression of hematoma or hemarthrosis is consistently reported for hemophilic patients. To study the manifestation of peripheral nerve lesions, an extensive nerve conduction study of peripheral nerves and specific nerves in correlation with clinical involvement was carried out on 126 hemophilic patients. We found 24 patients with 34 peripheral nerve lesions. The frequency of nerve lesion positively correlated with the severity of hemophilia (p < 0.01) and increasing age (p < 0.05). Nerve lesions occurred more commonly in lower extremities than in upper extremities. The femoral nerve was most commonly involved. Seven patients were identified to have mononeuropathy multiplex with 2 or more nerve lesions involving more than one extremity. All of these patients had chronic condition. Our findings suggest that mononeuropathy multiplex may occur in hemophilic patients.

Functional assessment of tibial-nerve recovery in the cat using gait analysis: preliminary study.

The purpose of this study was to investigate gait-pattern changes after complete tibial nerve lesion in the cat, and to observe whether nerve repair could reverse some of the changes. In six cats, a 5-cm segment of the tibial nerve was transected. The nerve gap was then repaired with nerve autograft in three animals and was unrepaired in three as controls. The walking patterns of the cats were videotaped, and the hip, knee, ankle, and metatarsophalangeal joint angles were measured at the beginnings of the F, E1, E2, and E3 phases of the step cycle. Two weeks after surgery, abnormal gait patterns were observed, and four gait parameters (E3.Hip, E3.Ankle, E3.M-P, and F.Ankle) were found to be statistically significantly different from normal. Six months after surgery, the nerve-graft group had gait-parameter values approaching normal, while the control group showed no measurable improvement. Correspondingly, electrophysiologic testing revealed considerable nerve regeneration in the nerve-graft group but not in the control group. It was concluded that these gait parameters can be used as valid functional indices to evaluate the degree of tibial nerve recovery in the cat model.

Assessment of intraspinal and intracranial conduction by P30 and P39 tibial nerve somatosensory evoked potentials in cervical cord, brainstem, and hemispheric lesions.

In routine recordings of tibial nerve somatosensory evoked potentials (SEPs), a global central conduction time is evaluated by measuring the interval between the segmental spinal N22 potential, recorded in the lumbar region, and the cortical P39 potential. In this study, we tested the reliability of the scalp far-field P30 potential, which originates in the vicinity of the cervico-medullary junction, in order to evaluate separately intraspinal and intracranial conduction in normal subjects and patients with cervical cord and intracranial lesions. P30 and cortical P39 potentials were studied in 23 healthy subjects and in 70 patients with cervical cord (n = 47), brainstem (n = 11) or hemispheric lesions (n = 12) selected on the basis of neuroimaging--computed tomography (CT) or magnetic resonance (MR)--findings. Median nerve SEPs were also recorded in all patients. Of the several montages tested to obtain the P30 potential, the Fpz-Cv6 derivation gave the highest signal-to-noise ratio; it permitted to obtain a P30 potential that peaked at 29.2 +/- 1.6 ms in all normal subjects. P30 abnormalities were observed only in patients with cervical or cervico-medullary lesions; these were associated with a normal P39 in only two of 33 abnormal recordings. Conversely, P30 was consistently normal in lesions situated above the cervico-medullary junction whether associated with normal, delayed, or reduced P39. P30 abnormalities were subclinical in 42% of abnormal recordings. All patients with normal tibial and median nerve SEPs on both sides had normal touch, joint, and vibration sensation in the four limbs. There was a strong correlation between tibial nerve P30 and median nerve P14 data in the whole series of patients; both potentials behaved similarly in all cases of intracranial supramedullary lesions. Combined abnormalities of P30 and P39 potentials thus indicate that conduction is impaired at the spinal level and proved to be particularly informative for detecting spinal cord dysfunction in patients with neuroimaging evidence of a narrowed cervical canal. Recording of abnormal N13, P14, or P30 potentials provided evidence of a cervical cord dysfunction in 66% of patients who had a suspected spondylotic myelopathy. Recording of tibial nerve P30 potential has proven to give reliable and useful information when a separate assessment of intraspinal and intracranial somatosensory conduction is needed; it merits inclusion, as does the upper limb N13 potential, in the evaluation of patients whose MR image indicates cervical canal narrowing.

A morphological and functional assessment of Mycobacterium leprae-induced nerve damage in a guinea-pig model of leprous neuritis.

Nerve damage, resembling that caused by Mycobacterium leprae in man, was created by the injection of cobalt-irradiated M. leprae organisms into the tibial nerve of guinea-pigs. Assessment of nerve damage was made by clinical, electrophysiological and morphometric means at intervals up to 13 weeks after injection. Quantitative immunohistochemical analysis of neuropeptide-containing fibres in the skin of the foot was also carried out. Significant nerve damage occurred 3 weeks after injection of M. leprae organisms. Motor and sensory functional loss peaked at 5 weeks after injection, and there was a significant decrease of peptide-immunoreactive nerves in all skin compartments. The nerve damage was self-limiting and functional recovery had occurred by 13 weeks. The model shows many of the features found in the nerve damage of treated leprosy patients.