Cerebellar hyperperfusion in semantic dementia.

Despite evidence of a cerebellar contribution to language, possible functional changes of the cerebellum in patients with language impairment secondary to cerebral neurodegeneration has not been investigated so far. We examined with resting perfusion single photon emission tomography one patient with semantic dementia and the data were compared with a normal subject database. Region of interest and Statistical Parametric Mapping 2 analysis showed in the patient hypoperfusion of the left temporal and parietal lobe and hyperperfusion in the superior vermis and cerebellar hemispheres (lobules IV, V, and VI). The cerebellum shows increased flow of possible compensatory significance in patients with language disturbance associated to cerebral degenerative changes.

Low brain iron content in idiopathic restless legs syndrome patients detected by phase imaging.

BACKGROUND: The objective of this study was to use phase imaging to evaluate brain iron content in patients with idiopathic restless legs syndrome (RLS). METHODS: Fifteen RLS patients and 15 healthy controls were studied using gradient-echo imaging. Phase analysis was performed on localized brain regions of interest selected on phase maps, sensitive to paramagnetic tissue. Differences between the 2 subject groups were evaluated using ANCOVA including age as a covariate. RESULTS: Significantly higher phase values were present in the RLS patients compared with healthy controls at the level of the substantia nigra, thalamus, putamen, and pallidum, indicating reduced iron content in several regions of the brain of the patients. CONCLUSIONS: We have used MRI phase analysis to study brain iron content in idiopathic RLS in vivo for the first time. Our results support the hypothesis of reduced brain iron content in RLS patients, which may have an important role in the pathophysiology of the disorder.

Abnormal medial thalamic metabolism in patients with idiopathic restless legs syndrome.

Pathophysiology of restless legs syndrome is poorly understood. A role of the thalamus, specifically of its medial portion which is a part of the limbic system, was suggested by functional magnetic resonance imaging and positron emission tomography studies. The aim of this study was to evaluate medial thalamus metabolism and structural integrity in patients with idiopathic restless legs syndrome using a multimodal magnetic resonance approach, including proton magnetic resonance spectroscopy, diffusion tensor imaging, voxel-based morphometry and volumetric and shape analysis. Twenty-three patients and 19 healthy controls were studied in a 1.5 T system. Single voxel proton magnetic resonance spectra were acquired in the medial region of the thalamus. In diffusion tensor examination, mean diffusivity and fractional anisotropy were determined at the level of medial thalamus using regions of interest delineated to outline the same parenchyma studied by spectroscopy. Voxel-based morphometry was performed focusing the analysis on the thalamus. Thalamic volumes were obtained using FMRIB's Integrated Registration and Segmentation Tool software, and shape analysis was performed using the FMRIB Software Library tools. Proton magnetic resonance spectroscopy study disclosed a significantly reduced N-acetylaspartate:creatine ratio and N-acetylaspartate concentrations in the medial thalamus of patients with restless legs syndrome compared with healthy controls (P < 0.01 for both variable). Lower N-acetylaspartate concentrations were significantly associated with a family history of restless legs syndrome (ß = -0.49; P = 0.018). On the contrary, diffusion tensor imaging, voxel-based morphometry and volumetric and shape analysis of the thalami did not show differences between the two groups. Proton magnetic resonance spectroscopic findings in patients with restless legs syndrome indicate an involvement of medial thalamic nuclei of a functional nature; however, the other structural techniques of the same region did not show any changes. These findings support the hypothesis that dysfunction of the limbic system plays a role in the pathophysiology of idiopathic restless legs syndrome.

Catathrenia under sodium oxybate in narcolepsy with cataplexy.

PURPOSE: This study aims to report on catathrenia occurring in narcolepsy with cataplexy (NC) patients under sodium oxybate (SO) treatment. Catathrenia is a parasomnia characterized by groaning and an abnormal respiratory pattern during sleep. METHODS: Fifty-one patients with NC and starting SO therapy underwent a baseline overnight polysomnography (PSG) to detect any sleep-related breathing disorders (SRBD). To avoid risks due to a possible central respiratory control depression by SO, all patients with concomitant obstructive sleep apnea (OSA) were treated with a nasal continuous positive airway pressure (nCPAP) device. After 2 months of treatment with SO, all patients underwent a follow-up overnight PSG to investigate possible newly occurring SRBD. They also underwent a semi-structured clinical interview to monitor other potential SO side effects. RESULTS: At baseline, four out of 51 patients showed simple snoring, and eight, mild to severe OSA. After a titration PSG night, patients with OSA received a nCPAP device. After 2 months of SO treatment, 28 patients (54.9%) showed SO-related side effects, including SRBD in 11 (21.6%). The follow-up PSG showed a respiratory pattern characteristic of catathrenia in seven patients (13.7%) as a newly observed and possibly benign SO side effect, and ruled out a worsening of OSA. CONCLUSIONS: Catathrenia should be considered a possible side effect in NC patients under SO treatment and should be accurately identified to prevent unnecessary SO withdrawal.

Group I nonreciprocal inhibition in restless legs syndrome secondary to chronic renal failure.

BACKGROUND: Neurophysiological investigations disclosed spinal cord hyperexcitability in primary restless legs syndrome (p-RLS). Uremic RLS (u-RLS) is the most common secondary form, but its pathophysiological mechanisms remain unsettled. Aim of this study was to explore spinal cord excitability by evaluating group I nonreciprocal (Ib) inhibition in u-RLS patients in comparison with p-RLS patients and healthy subjects. METHODS: Eleven u-RLS patients undergoing long-term hemodialysis treatment, nine p-RLS patients and ten healthy subjects were studied. Soleus H reflex latency (HR-L), H(max)/M(max) ratio, and Ib inhibition were evaluated. Ib inhibition was tested measuring the amplitude changes in soleus H reflex following stimulation of the synergist gastrocnemius medialis (GM) nerve at rest. Nerve conduction studies were performed in the uremic patients. RESULTS: The H(max)/M(max) ratio did not differ in the three groups. The u-RLS patients showed a normal Ib inhibition comparable with the healthy group, whereas the p-RLS group had evidence of a reduced active inhibition compared with both u-RLS patients (P = 0.04) and controls (P = 0.007), prominently at 5 ms (P = 0.007) and at 6 ms (P = 0.02) of conditioning-test interval. Neurophysiological examination disclosed abnormalities ranging from higher HR-L to clear-cut polyneuropathy in most u-RLS patients. CONCLUSIONS: Unlike p-RLS patients, u-RLS patients had normal Ib inhibition, suggesting a regular supraspinal control of Ib spinal interneurons. Subclinical peripheral nerve abnormalities were detected in most uremic patients. Peripherally disrupted sensory modulation may represent the major pathophysiological determinant of uremic RLS.

Sleep-to-wake transition movement disorders.

Consciousness and vigilance level are important factors for the manifestation and variability of many disorders, including movement disorders. Usually lumped together into unspecified "Wakefulness," the transition between wakefulness and sleep--the pre-dormitum, and between sleep and wakefulness--the post-dormitum, possess intrinsic cerebral metabolic patterns and mental, behavioural, and neurophysiological characteristics which make these peculiar states of vigilance independent. Moreover, the pre- and post-dormitum, with the relative state-dependent changes in firing patterns of many neuronal supra-pinal populations, act to release pacemakers responsible for different sleep-related motor phenomena. The relevance of pre-dormitum and post-dormitum as states different from full wakefulness and full sleep is, indeed, indicated by disorders which appear exclusively during either state, including motor disorders such as propriospinal myoclonus and awakening epilepsy. We will focus on three paradigmatic physiological/pathological motor phenomena (rhythmic movement disorder, hypnic jerks, and propriospinal myoclonus) strictly linked to the sleep-wake transition periods. Thereafter we will briefly discuss how the process of pre-dormitum and post-dormitum can lead to such disruption of motor control.

From REM sleep behaviour disorder to status dissociatus: insights into the maze of states of being.

Sleep is a coordinated process involving more or less simultaneous changes in sensory, motor, autonomic, hormonal, and cerebral processes. On the other hand, none of the changes occurring with sleep are invariably coupled to sleep. EEG synchrony, heat loss, sleep-related hormone secretion, and even REM-related motoneuron paralysis may occur independent of the parent state. In REM sleep behaviour disorder (RBD) the muscle tone of wakefulness intrudes into REM sleep, allowing the release of dream-enacting behaviours. Status dissociatus (SD) is a condition in which brain and mind are in disarray along the boundaries of sleep and wakefulness. The existence of such dissociated behaviours shows that they have separate neuronal control systems and indicates that the whole organization of sleep is an emergent property of the collective neuronal systems to synchronize. Insults to the brain can drastically alter the circuitries responsible for maintaining the integrity of wakefulness, NREM sleep, and REM sleep. As a consequence, the basic states of existence can become admixed and interchanged with striking disturbances of consciousness, brain electrophysiology, and the behavioural and polygraphic expression of sleep and wakefulness. The evolution of RBD into SD may result from a disarray of (brainstem) structures that orchestrate the whole brain wake-sleep conditions, but with preserved discrete systems and dissociable strategies to still place navigation in wake and sleep. Advances in the fields of genetics, neuroimaging, and behavioural neurology will expand the understanding of the mechanisms underlying the organization of the states of being along with their somatic/behavioural manifestations.

Normal body scheme and absent phantom limb experience in amputees while dreaming.

While dreaming amputees often experience a normal body image and the phantom limb may not be present. However, dreaming experiences in amputees have mainly been collected by questionnaires. We analysed the dream reports of amputated patients with phantom limb collected after awakening from REM sleep during overnight videopolysomnography (VPSG). Six amputated patients underwent overnight VPSG study. Patients were awakened during REM sleep and asked to report their dreams. Three patients were able to deliver an account of a dream. In all dreaming recalls, patients reported that the amputated limbs were intact and completely functional and they no longer experienced phantom limb sensations. Phantom limb experiences, that during wake result from a conflict between a pre-existing body scheme and the sensory information on the missing limb, were suppressed during sleep in our patients in favour of the image of an intact body accessed during dream.

Autonomic disturbances in narcolepsy.

Narcolepsy is a clinical condition characterized mainly by excessive sleepiness and cataplexy. Hypnagogic hallucinations and sleep paralysis complete the narcoleptic tetrad; disrupted night sleep, automatic behaviors and weight gain are also usual complaints. Different studies focus on autonomic changes or dysfunctions among narcoleptic patients, such as pupillary abnormalities, fainting spells, erectile dysfunction, night sweats, gastric problems, low body temperature, systemic hypotension, dry mouth, heart palpitations, headache and extremities dysthermia. Even if many studies lack sufficient standardization or their results have not been replicated, a non-secondary involvement of the autonomic nervous system in narcolepsy is strongly suggested, mainly by metabolic and cardiovascular findings. Furthermore, the recent discovery of a high risk for overweight and for metabolic syndrome in narcoleptic patients represents an important warning for clinicians in order to monitor and follow them up for their autonomic functions. We review here studies on autonomic functions and clinical disturbances in narcoleptic patients, trying to shed light on the possible contribute of alterations of the hypocretin system in autonomic pathophysiology.

Insomnia cycling with a 42-day infradian period: evidence for two uncoupled circadian oscillators?

OBJECTIVE: To describe the unique case of a middle-aged woman with severe insomnia recurring with a regular infradian period without any other significant clinical condition. To infer the existence of a circadian dysfunction modeled according to the physical phenomenon of the "beats." PATIENT/METHODS: A two-year prospective observation by means of a sleep log was performed during the patient's normal life. She underwent one month of motor activity recording and also polysomnography, circadian rhythm of body core temperature and psychiatric evaluation during periods with and without insomnia. RESULTS: Visual inspection of the 293-day plot of the sleep log disclosed a regular 42-day rhythm of insomnia recurrence confirmed by a Discrete Fourier Transform. During the periods of insomnia, lasting 5-7days, only moderate mood symptoms (depressive overlapping hypomaniac symptoms) were present. Treatment with sodium valproate was effective in curtailing insomnia. CONCLUSION: The wax and wane infradian modulation of the sleep length suggested the presence of a basic mechanism similar to the physical phenomenon of the "beats," i.e., a long period modulation of the amplitude of an oscillating system due to the interference of two uncoupled oscillators with a slightly different oscillation frequency. Hypothesizing a dysfunction of the circadian component of sleep, namely two uncoupled circadian cycles, a simple mathematical model estimated the difference of their periods of oscillation |34+/-2min| and reproduced the sleep-log data of the drug-free period of observation.

Behavioural and neurophysiological correlates of human cataplexy: a video-polygraphic study.

OBJECTIVES: To investigate the behavioural and neurophysiological pattern of cataplexy. METHODS: Seven narcolepsy with cataplexy patients underwent daytime videopolygraphy using humorous movies or/and jokes to trigger cataplectic attacks. RESULTS: During segmental cataplectic attacks, EMG showed brief and irregular periods of silencing focally involving facial, neck, axial or limb muscles, sometimes coinciding with bursts of rapid eye movements. All patients enacted intentional movements in response to these segmental postural lapses. During global cataplectic attacks, EMG showed suppression of activity alternated with patterned enhancement, enhanced EMG activity in neck muscles preceding that of other cranial, axial and lower limb muscles. This waxing and waning EMG pattern ended with a complete body collapse and persistent muscle atonia. Breathing irregularities, heart rate (HR) instability and EEG desynchronization were observed during global cataplectic attacks without any appreciable blood pressure changes, but with HR deceleration and silencing of sympathetic skin response while in complete atonia. Patients subjectively perceived the involuntary postural lapses as startling and alarming. CONCLUSIONS: Cataplexy in our patients showed many of the features of tonic REM sleep. SIGNIFICANCE: Cataplexy can be construed as a "freezing-like" perturbation of the orienting response with transient impairment of posture and movements resulting in a "patchwork-compromise-behaviour".