Elastic and magnetic dynamics of nanomagnet-ordered arrays impulsively excited by subpicosecond laser pulses.

This Letter reports on the first observation of elastic and magnetic dynamics of ordered arrays of permalloy nanodots excited by low-intensity 120 fs light pulses. The first order of the diffraction pattern, generated by the probe beam in a pump-probe configuration, is used for time-resolved reflectivity and time-resolved magneto-optical Kerr effect measurements. The nonadiabatical absorption of the pump triggers an acoustic standing wave, detected by the reflected probe signal, with a frequency related to the array wave vector. Instead, the magneto-optical signal exhibits, on the nanosecond time scale, the signature of the heat-exchange diffusion processes. In addition, a clear oscillation of the magnetic signal, at a frequency close to the frequency of the acoustic wave, is unambiguously detected. Finally, the interplay between the elastic and magnetic dynamics is analyzed and interpreted.

Continuous focal spikes during REM sleep in a case of acquired aphasia (Landau-Kleffner syndrome).

We report a girl 3 years and 6 months old with onset of aphasia at age 3 years and 3 months. There was no evidence of brain damage and there were no seizures. The neuropsychological evaluation showed that the girl tended to be right-handed, that aphasia was global and that other higher cortical functions seemed to be preserved. Isolated spikes and spikes-and-wave were recorded during wake over the right temporal region with rare independent contralateral abnormalities. During polysomnography (PSG), the physiological patterns of sleep were preserved and right temporal epileptiform discharges were significantly increased in all sleep stages. Maximal activation was obtained at sleep onset and during rapid eye movement (REM) sleep periods, when focal abnormalities became continuous and spread contralaterally. Repeat PSGs showed that the activation profile retained this particular trait, although subclinical discharges tended to increase during slow wave sleep (SWS). This pattern of subclinical temporal status epilepticus during REM sleep differs from the characteristic activation profile found in the syndrome of continuous spikes-and-waves during SWS. However, this profile was transient and all epileptiform changes disappeared during clinical recovery at 18 months of follow-up.

Intracranial microvascular decompression for "cryptogenic" hemifacial spasm, trigeminal and glossopharyngeal neuralgia, paroxysmal vertigo and tinnitus: II. Clinical study and long-term follow up.

20 patients who had undergone microvascular decompression for the treatment of "idiopathic" trigeminal neuralgia (9 cases), hemifacial spasm (7 cases), glossopharyngeal neuralgia (3 cases) and paroxysmal vertigo and tinnitus (1 case) were followed up for 25 months on average. Permanent relief of symptoms was observed in 19 (95%), with sparing of cranial nerve function. Analysis of the clinical data shows that the patients described in the present series did not differ from those considered to suffer from "idiopathic" cranial nerve dysfunction syndromes. The importance of vascular cross compression as etiological factor in such conditions is stressed and the pathophysiology discussed. The term "cryptogenic" applied to trigeminal neuralgia or hemifacial spasm thus needs revising. Lastly, the indications of microvascular decompression in the treatment of "cryptogenic" cranial nerve dysfunction syndromes are defined.