JaNean K. Engelstad

Chronic immune sensory polyradiculopathy A possibly treatable sensory ataxia

Background: Chronic inflammatory neuropathies can present with a sensory ataxia due to involvement of dorsal root ganglia (DRG) or sensory nerves. Selective inflammatory involvement of sensory nerve roots proximal to the DRG has been postulated. Methods: The authors identified 15 patients with a sensory syndrome and normal nerve conduction studies. Sensory nerve root involvement was suggested by either somatosensory evoked potential (SSEP) or imaging abnormalities. CNS disease was excluded. Results: All patients had gait ataxia, large fiber sensory loss, and paresthesias, and nine had frequent falls. The disease course was chronic and progressive (median duration 5 years, range 3 months to 18 years). Sural sensory nerve action potential amplitudes were preserved and SSEP abnormalities were consistent with sensory nerve root involvement. Five patients had enlargement of lumbar nerve roots on MRI with enhancement in three. The CSF protein was elevated in 13 of 14 patients tested. Three patients had lumbar sensory rootlet biopsies that showed thickened rootlets, decreased density of large myelinated fibers, segmental demyelination, onion-bulb formation, and endoneurial inflammation. Six patients who required aids to walk were treated with immune modulating therapy and all had marked improvement with four returning to normal ambulation. Conclusion: Based on the described clinical features, normal nerve conduction studies, characteristic somatosensory evoked potential (SSEP) abnormality, enlarged nerve roots, elevated CSF protein, and inflammatory hypertrophic changes of sensory nerve rootlet tissue, we suggest the term chronic immune sensory polyradiculopathy (CISP) for this syndrome. This condition preferentially affects large myelinated fibers of the posterior roots, may respond favorably to treatment, and may be a restricted form of chronic inflammatory demyelinating polyradiculoneuropathy.

Misdirection of regenerating motor axons after nerve injury and repair in the rat sciatic nerve model

Misdirection of regenerating axons is one of the factors that can explain the poor results often found after nerve injury and repair. In this study, we quantified the degree of misdirection and the effect on recovery of function after different types of nerve injury and repair in the rat sciatic nerve model; crush injury, direct coaptation, and autograft repair. Sequential tracing with retrograde labeling of the peroneal nerve before and 8 weeks after nerve injury and repair was performed to quantify the accuracy of motor axon regeneration. Digital video analysis of ankle motion was used to investigate the recovery of function. In addition, serial compound action potential recordings and nerve and muscle morphometry were performed. In our study, accuracy of motor axon regeneration was found to be limited; only 71% (+/-4.9%) of the peroneal motoneurons were correctly directed 2 months after sciatic crush injury, 42% (+/-4.2%) after direct coaptation, and 25% (+/-6.6%) after autograft repair. Recovery of ankle motion was incomplete after all types of nerve injury and repair and demonstrated a disturbed balance of ankle plantar and dorsiflexion. The number of motoneurons from which axons had regenerated was not significantly different from normal. The number of myelinated axons was significantly increased distal to the site of injury. Misdirection of regenerating motor axons is a major factor in the poor recovery of nerves that innervate different muscles. The results of this study can be used as basis for developing new nerve repair techniques that may improve the accuracy of regeneration.

Vascular endothelial growth factor and POEMS

In this issue, Kuwabara et al.1 report on the use of high-dose melphalan and autologous peripheral blood stem cell transplantation (auto-PBSCT, four patients) and high-dose melphalan only (eight patients) in treatment of POEMS (polyneuropathy, organomegaly, endocrinopathy, M-protein and skin changes) syndrome, typical features of which are illustrated in the figure. As reported previously2,3 and again here, POEMS is associated with markedly increased serum levels of vascular endothelial growth factor (VEGF), an increase attributed to the underlying plasma proliferative disorder, because the serum level of this cytokine decreases with ablation or irradiation of the osteosclerotic myeloma. Such increases of VEGF are not found in acute or chronic inflammatory demyelinating polyneuropathy other neurologic disorders,3 monoclonal gammopathy of undetermined significance,4,5 or multiple myeloma.5 In the currently reported cases, with auto-PBSCT treatment, the symptoms of POEMS improved, and the serum VEGF levels decreased dramatically to normal or near-normal levels. By contrast, with low-dose melphalan therapy, the effects were not as large, were …

Painless diabetic motor neuropathy: A variant of diabetic lumbosacral radiculoplexus Neuropathy?

Occasionally, diabetic patients develop painless, lower‐limb, motor predominant neuropathy. Whether this is a variant of diabetic lumbosacral radiculoplexus neuropathy (DLRPN) (a painful disorder from ischemic injury and microvasculitis), a variant of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) or another disorder is unsettled. Here, we characterize the clinical and pathological features of painless diabetic motor predominant neuropathy.

No Evidence for Axonal Atrophy in Human Diabetic Polyneuropathy

In rats with streptozin-induced diabetes mellitus, the caliber of distal myelinated fiber (MF) axons in relation to the number of myelin lamellae is smaller than in controls. This finding usually has been attributed to axonal atrophy, but shrinkage or maldevelopment has also been considered. For human diabetic polyneuropathy (DP), axonal atrophy has been assumed by some investigators, but convincing evidence has not been demonstrated. We morphometrically evaluated transverse sections of 33 sural nerves from carefully evaluated diabetic patients ≥ 30 years old without (8 patients) or with (25 patients) DP and compared them with 24 nerves from healthy subjects ≥ 30 years old. Nerves from diabetic patients and controls were obtained under identical conditions and processed and evaluated in the same way, using an observer blind to the disease condition. Using computer digitization of electron micrographs, we evaluated the axonal area, perimeter, index of circularity, number of myelin lamellae, and frequency of adaxonal sequestration of 50.4 (mean) ± 5.8 (SD) MF per sural nerve for healthy subjects and diabetic patients ≥ 30 years old. The regression lines of the natural log (In) of axonal area on number of myelin lamellae of diabetic patients (with or without DP) were not significantly different from the regression lines of nerves of healthy subjects for large MFs—the most reliable group in which to recognize atrophy. Likewise, the regression lines of index of circularity (IC) (an index that is decreased with atrophy or shrinkage) on number of myelin lamellae for large fibers was not significantly different between the disease and control groups. The rate of adaxonal sequestration was not significantly higher in DP than in healthy subjects. These results do not support the hypothesis that axonal atrophy occurs in human DP. For small MF. or all MF. some significant differences in regression lines of In axonal area or IC on number of lamellae were found, but these changes are probably explained by events of remyelination and axonal regeneration, which can affect these relationships and are known to occur in DP.

Microvasculitis in Diabetic Lumbosacral Radiculoplexus Neuropathy

We present a case of a 60-year-old man with mild type 2 diabetes mellitus and step-wise progression of bilateral lower limb weakness, numbness, and pain over a 1-year period. At the time of evaluation, he used a walker. He had elevated cerebrospinal fluid protein, abnormal cooling and heat-pain thresholds on quantitative sensory testing, and nerve conduction studies/electromyography consistent with bilateral lumbosacral radiculoplexus neuropathies. Because it was not clear whether the disease was still active, a right superficial peroneal nerve biopsy was performed and showed evidence of active axonal degeneration, ischemic injury, and microvasculitis. On the basis of these results, the patient was diagnosed with diabetic lumbosacral radiculoplexus neuropathy and was treated with weekly intravenous methylprednisolone with marked improvement of neurologic symptoms and signs. This case illustrates the typical clinical, electrophysiologic, and pathologic features of diabetic lumbosacral radiculoplexus neuropathy and the utility of nerve biopsy to judge ongoing disease activity.

Epidermal nerve fibers Confidence intervals and continuous measures with nerve conduction

ABSTRACT Objectives: Our first objective was to explore the value of estimating 95% confidence intervals (CIs) of epidermal nerve fibers (ENFs)/mm for number of sections to be evaluated and for confidently judging normality or abnormality. Our second objective was to introduce a new continuous measure combining nerve conduction and ENFs/mm. Methods: The 95% CI studies were performed on 1, 1–2, 1–3 - - - 1–10 serial skip sections of 3-mm punch biopsies of leg and thigh of 67 healthy subjects and 23 patients with diabetes mellitus. Results: Variability of differences of ENFs/mm counts (and 95% CIs) from evaluation of 1, 1–2, 1–3 - - - 1–9 compared with 1–10 serial skip sections decreased progressively without a break point with increasing numbers of sections evaluated. Estimating 95% CIs as sections are evaluated can be used to judge how many sections are needed for adequate evaluation, i.e., only a few when counts and 95% CIs are well within the range of normality or abnormality and more when values are borderline. Also provided is a methodology to combine results of nerve conduction and ENFs/mm as continuous measures of normality or abnormality. Conclusion: Estimating 95% CIs of ENFs/mm is useful to judge how many sections should be evaluated to confidently declare counts to be normal or abnormal. Also introduced is a continuous measure of both large-fiber (nerve conduction) and small-fiber (ENFs/mm) normal structures/functions spanning the range of normality and abnormality for use in therapeutic trials.

Chronic meralgia paresthetica and neurectomy: a clinical pathologic study.

Objective: To understand the pathologic and clinical correlates of patients with chronic meralgia paresthetica (MP) undergoing lateral femoral cutaneous nerve (LFCN) neurectomy. Methods: A retrospective cohort approach was utilized to identify 7 patients undergoing LFCN neurectomy for intractable pain. Control autopsied LFCN was obtained. Clinical, radiologic, and electrophysiologic features were reviewed. Results: In identified cases, preoperative symptoms included severe lateral thigh pain and numbness. The duration of symptoms prior to surgery ranged from 2 to 15 years. Body mass index (BMI) varied from 20 kg/m2 to 44.8 kg/m2 (normal–morbidly obese), with 6 out of 7 patients being obese. No patients were diabetic. Focal nerve indentation at the inguinal ligament was seen intraoperatively and on gross pathology in 4 of 7 cases. Multifocal fiber loss, selective loss of large myelinated fibers, thinly myelinated profiles, regenerating nerve clusters, perineurial thickening, and subperineurial edema were seen. None of these features were observed in control nerve. Morphometric analysis confirmed loss of large myelinated fibers with small and intermediate size fiber predominance. Five patients had varying degrees of intraneural and epineurial inflammation. Six of 7 reported improved pain after neurectomy, sometimes dramatic. Conclusions: Patients with chronic MP and intractable pain have an LFCN mononeuropathy with loss of nerve fibers. Pathologic and clinical study supports a compressive pathogenesis as the primary mechanism. Abnormal nerve inflammation coexists and may play a role in pathogenesis. These selected patients typically benefited from neurectomy at a site of inguinal ligament compression. Classification of Evidence: This study provides Class IV evidence that patients with chronic MP LFCN neurectomy experience improvement in MP-related pain.

Clinical-pathologic correlations in voltage-gated Kv1 potassium channel complex-subtyped autoimmune painful polyneuropathy

Introduction: Voltage‐gated Kv1 potassium channel complex (VGKC) autoantibodies subtyped for leucine‐rich glioma‐inactivated 1 (LGI1), contactin‐associated‐proteinlike 2 (CASPR2), and Kv IgGs have a spectrum of neurological presentations. Painful polyneuropathy is seen in some patients, but nerve pathology descriptions are lacking. Methods: Clinicopathologic features were studied in subtyped VGKC‐autoantibody‐seropositive patients who had undergone nerve biopsies. Results: Five patients were identified, 1 LGI1 IgG positive and 1 CASPR2 IgG positive, but all negative for Kv1.1‐, 1.2‐, 1.6‐subtyped IgG autoantibodies. Median symptom duration was 17 months. Pain was the predominant symptom; 3 had mild sensory loss and/or weakness. Histopathological abnormalities were limited to axonal loss in 3. None had mononuclear cellular infiltrates. Electron micrographs revealed no interstitial abnormalities. Three patients reported marked improvement in pain with immunotherapy. Conclusions: The nerve biopsy histopathology of patients subtyped for LGI1 and CASPR2 IgGs within the VGKC‐complex spectrum disorders shows either normal density or axonal fiber loss without inflammatory infiltrates. A reversible neural hyperexcitable mechanism is considered to be the cause of this painful polyneuropathy. Muscle Nerve 55: 520–525, 2017

Vasculitic neuropathy following exposure to minocycline

Objective: To report 3 patients with minocycline-induced autoimmunity resulting in peripheral nerve vasculitis. Methods: We report 3 patients who, during minocycline treatment for acne vulgaris, developed subacute onset of pain and weakness caused by vasculitis in single and multiple mononeuropathy patterns. Results: Each patient underwent either a nerve or muscle biopsy that confirmed vasculitis. One patient additionally developed systemic symptoms (including fever, fatigue, and night sweats) and another had a posterior circulation stroke. Symptoms developed with either early or prolonged use of minocycline. Despite withdrawal of minocycline, patients needed long-term immunotherapy to gain neurologic improvement. Conclusions: Our findings suggest that the typical neuropathy associated with minocycline use is painful single or multiple mononeuropathy due to peripheral nerve vasculitis, which may also be accompanied by presumed CNS vasculitis (presenting as stroke).