Neurofibromatous neuropathy: An ultrastructural study.

Plexiform neurofibroma is pathognomonic of neurofibromatosis 1 (NF1). An NF1-associated peripheral neuropathy has been described in a small minority of NF1 patients but its histopathological features are poorly characterized. We report the case of a 46-year-old woman presenting with bilateral supraclavicular painful masses without other stigmata of NF1. MRI showed bilateral plexiform lesions extending from cervical roots to the elbows. Nerve conduction studies documented a sensory motor polyneuropathy. Morphometric analysis of sural nerve biopsy showed a preferential loss of large-caliber myelinated fibers with a g ratio of 0.515, and the presence of regeneration clusters. By electron microscopy, marked and diffuse endoneurial fibrosis with an altered relationship between Schwann cells (SC) and collagen fibrils was observed. Moreover both myelinating and non-myelinating SC were characterized by the presence of various cell degradation products. These changes suggest that, in neurofibromatous neuropathy, a widespread axonal atrophy and degeneration take place independently on the presence of tumoral infiltration, possibly due to an impairment in SC-axon cross talk. In this case, the coexistence of plexiform neurofibromas with a peripheral neuropathy strongly suggests a diagnosis of NF1 even without fulfillment of clinical criteria. We propose that in the presence of plexiform neurofibromas, electrophysiological studies should be performed also in asymptomatic patients, in order to detect the existence of a subclinical neuropathy.

Percutaneous tibial nerve stimulation produces effects on brain activity: study on the modifications of the long latency somatosensory evoked potentials.

OBJECTIVE: Long-latency somatosensory evoked potentials (LL-SEP) provide information on the function of somatosensory cortical structures. Percutaneous tibial nerve stimulation (PTNS) is indicated in the treatment of lower urinary tract dysfunction. Aim of this study was to evaluate LL-SEP in patients with overactive bladder syndrome (OAB) treated by means of PTNS. METHODS: Sixteen female patients with a diagnosis of pharmacoresistant OAB underwent PTNS while eight female patients with the same diagnosis underwent sham stimulation. LL-SEP were performed at baseline and at the end of PTNS or sham stimulation. Peak latency and peak to peak amplitude of P80, P100, and P200 waves were measured. RESULTS: Mean latency of P80, P100, and P200 and mean amplitude of P200 did not show any significant change after both stimulation. Mean amplitude of P80 and P100 waves increased significantly after PTNS while it did not vary after sham stimulation. CONCLUSION: The P80 and P100 amplitude increase might reflect long-term modifications in synaptic efficiency through the somatosensory pathway. The plastic reorganization of cortical network triggered by peripheral neuromodulation can be hypothesized as a mechanism of action of PTNS. Further studies are needed to correlate LL-SEP modifications after PTNS with the success of the treatment.

Epileptic spasms and partial seizures as a single ictal event.

PURPOSE: To investigate the phenomenon of epileptic spasms (ESs) associated with other seizure types in a single ictal event and to study the predictive value of this phenomenon regarding etiology and prognosis. METHODS: We selected retrospectively eight female and five male patients, who had ESs and other seizure types within a single seizure event and for whom a video-EEG recording of the phenomenon was performed in at least one situation. RESULTS: The seizure type associated with ESs was a partial seizure in all patients. We identified three groups with different seizure patterns regarding the temporal association of ES and partial seizures (PSs): (a) PS followed by ES; (b) PS appearing during a cluster of ESs without interrupting the cluster; and (c) complex seizure interaction with a succession of ESs and PSs in a close but variable temporal association. Underlying disorders included cortical dysplasia (three patients), complex cerebral malformations (two patients), and perinatal anoxic-ischemic injuries (two patients); four cases were classified as cryptogenic, and in two children, etiology was unknown, but prenatal origin was suspected. Outcome was poor in nine cases with intractable epilepsy; four cases had a favorable outcome, defined as complete cessation of epileptic seizures. CONCLUSIONS: The phenomenon of associated ESs and PSs as a single ictal event can be related to different etiologies and should not be considered distinctive for cortical malformations or severe brain damage. Different seizure patterns of associated ESs and PSs provide no hint for etiology or prognosis. Outcome is prevalently but not constantly unfavorable in patients with the phenomenon.