Creutzfeldt-Jakob disease masked by head trauma and features of Wilson's disease.

Creutzfeldt-Jakob disease (CJD) is a fatal neurodegenerative disorder typically characterized by progressive dementia associated with myoclonus, cerebellar and other focal neurological signs. Electroencephalogram, brain MRI and cerebrospinal fluid (CSF) analyses are helpful diagnostic tools, but diagnosis in patients with atypical presenting neurological signs is often difficult to make. A 55-year-old woman developed disorientation, drowsiness and focal motor signs after a traumatic brain injury due to an accidental fall. In two weeks, her symptoms worsened in spite of a brain MRI showed an improvement of traumatic lesions, but the presence of bilateral hyperintensity in the basal nuclei was suggestive of a metabolic or prion encephalopathy. The high 24-h urinary copper level and reduction of ceruloplasmin initially supported the diagnosis of Wilson's disease, but the absence of Kayser-Fleischer rings, and the positivity of 14-3-3 protein test and elevated tau concentrations in the CSF oriented toward a diagnosis of CJD. She died 5 months after the onset, and the postmortem examination of the brain revealed immunochemical features of CJD. This case exemplifies the difficulty of a timely diagnosis when rapid progressive dementia is masked by concomitant factors (i.e., head trauma) and neurological signs are associated with unclear laboratory findings.

Somatosensory temporal discrimination tested in patients receiving botulinum toxin injection for cervical dystonia.

We designed this study to find out more about the relationship between the sensory effects of Botulinum toxin type A (BTX) and the clinical benefits of BTX therapy in patients with cervical dystonia (CD). In 24 patients with CD, we tested sensory temporal discrimination (STD) in the affected and two unaffected body regions (neck, hand, and eye) before and 1 month after BTX injection. In 8 out of the 24 patients with CD, STDT values were tested bilaterally in the three body regions before, 1 and 2 months after BTX injection. As expected, STD testing disclosed altered STD threshold values in all three body regions tested (affected and unaffected by dystonic spasms) in patients with CD. STD threshold values remained unchanged at all time points of the follow-up in all CD patients. The lack of BTX-induced effects on STD thresholds suggests that STD recruits neural structures uninvolved in muscle spindle afferent activation.

Heroin sensitization as mapped by c-Fos immunoreactivity in the rat striatum.

Immunohistochemistry was used to map the induction of c-Fos protein in the forebrain of rats treated with heroin. Acute injection of heroin to drug-naive rats caused significant induction of c-Fos protein in the nucleus accumbens shell, whereas the same dose of heroin given to drug-sensitized rats significantly increased c-Fos immunoreactivity in the dorsomedial caudate-putamen. These results show that the heroin-induced pattern of c-Fos protein in the rat striatum differs according to the rat's drug history. These findings may represent a neural correlate of the motor components of heroin sensitization.

Theta-burst stimulation-induced plasticity over primary somatosensory cortex changes somatosensory temporal discrimination in healthy humans.

BACKGROUND: The somatosensory temporal discrimination threshold (STDT) measures the ability to perceive two stimuli as being sequential. Precisely how the single cerebral structures contribute in controlling the STDT is partially known and no information is available about whether STDT can be modulated by plasticity-inducing protocols. METHODOLOGY/PRINCIPAL FINDINGS: To investigate how the cortical and cerebellar areas contribute to the STDT we used transcranial magnetic stimulation and a neuronavigation system. We enrolled 18 healthy volunteers and 10 of these completed all the experimental sessions, including the control experiments. STDT was measured on the left hand before and after applying continuous theta-burst stimulation (cTBS) on the right primary somatosensory area (S1), pre-supplementary motor area (pre-SMA), right dorsolateral prefrontal cortex (DLPFC) and left cerebellar hemisphere. We then investigated whether intermittent theta-burst stimulation (iTBS) on the right S1 improved the STDT. After right S1 cTBS, STDT values increased whereas after iTBS to the same cortical site they decreased. cTBS over the DLPFC and left lateral cerebellum left the STDT statistically unchanged. cTBS over the pre-SMA also left the STDT statistically unchanged, but it increased the number of errors subjects made in distinguishing trials testing a single stimulus and those testing paired stimuli. CONCLUSIONS/SIGNIFICANCE: Our findings obtained by applying TBS to the cortical areas involved in processing sensory discrimination show that the STDT is encoded in S1, possibly depends on intrinsic S1 neural circuit properties, and can be modulated by plasticity-inducing TBS protocols delivered over S1. Our findings, giving further insight into mechanisms involved in somatosensory temporal discrimination, help interpret STDT abnormalities in movement disorders including dystonia and Parkinson's disease.

Phasic voluntary movements reverse the aftereffects of subsequent theta-burst stimulation in humans.

Theta-burst stimulation (TBS) is a technique that elicits long-lasting changes in the excitability of human primary motor cortex (M1). Tonic contraction of the target muscle modifies the aftereffects of TBS, whereas interactions between phasic muscle contraction and the aftereffects of TBS are unknown. In this paper, we investigated whether phasic voluntary movements influence TBS-induced changes in M1 excitability. We examined whether a brief sequence of phasic finger movements performed by healthy humans before both intermittent TBS (iTBS) and continuous TBS (cTBS) influences TBS-induced aftereffects. Ten healthy subjects underwent iTBS and cTBS. To evaluate the TBS-induced aftereffects on M1 excitability, single TMS pulses were given over the FDI motor area before (T0) and 5 (T1), 15 (T2), and 30 min (T3) after TBS. To find out whether finger movements influenced the TBS-induced aftereffects, we tested motor-evoked potentials (MEPs) size by single TMS pulses at T0, immediately after movements, and at T1-T3. We also measured the kinematic variables mean amplitude and mean peak velocity of the movements. When no phasic voluntary movements preceded TBS, iTBS elicited facilitatory and cTBS elicited inhibitory aftereffects on MEP size. Conversely, movements performed before TBS elicited significant changes in the direction of the TBS-induced aftereffects. iTBS produced inhibitory instead of facilitatory aftereffects and cTBS produced facilitatory instead of inhibitory aftereffects. Finger movements alone had no effects on MEPs size tested with single-pulse TMS. Peripheral electrical stimulation had no effect on iTBS-induced aftereffects. Repeated phasic finger movements interfere with TBS-induced aftereffects probably by modulating mechanisms of brain metaplasticity.