Misericordia Veciana

Music-Supported Therapy induces plasticity in the sensorimotor cortex in chronic stroke: A single-case study using multimodal imaging (fMRI-TMS)

Primary objective: Music-Supported Therapy (MST) has been developed recently in order to improve the use of the affected upper extremity after stroke. This study investigated the neuroplastic mechanisms underlying effectiveness in a patient with chronic stroke. Methods: MST uses musical instruments, a midi piano and an electronic drum set emitting piano sounds, to retrain fine and gross movements of the paretic upper extremity. Data are presented from a patient with a chronic stroke (20 months post-stroke) with residual right-sided hemiparesis who took part in 20 MST sessions over the course of 4 weeks. Results: Post-therapy, a marked improvement of movement quality, assessed by 3D movement analysis, was observed. Moreover, functional magnetic resonance imaging (fMRI) of a sequential hand movement revealed distinct therapy-related changes in the form of a reduction of excess contralateral and ipsilateral activations. This was accompanied by changes in cortical excitability evidenced by transcranial magnetic stimulation (TMS). Functional MRI in a music listening task suggests that one of the effects of MST is the task-dependent coupling of auditory and motor cortical areas. Conclusions: The MST appears to be a useful neurorehabilitation tool in patients with chronic stroke and leads to neural reorganization in the sensorimotor cortex.

Sympathetic sudomotor skin responses induced by laser stimuli in normal human subjects

Laser stimuli (LS) were used to induce sudomotor skin responses (SSRs) in ten healthy human subjects. LS were applied to the dorsum of the hand by means of a CO(2) laser stimulator at an intensity of 120% pain perception threshold. SSRs induced by LS were of longer latency than those induced by electrical stimuli. However, response amplitude and duration were similar with either stimuli. The possibility to activate the sudomotor system by means of stimulation of pain afferents might be of clinical applicability for the functional assessment of pain pathways.

Abnormal sudomotor skin responses to temperature and pain stimuli in syringomyelia.

Thermoalgesic sensory deficits in patients with syringomyelia may escape objective documentation with conventional electrophysiological techniques. We examined six patients with radiologically proven centrospinal cavities and patchy thermoalgesic sensory deficits by recording the evoked potentials and the sympathetic sudomotor skin responses (SSR) to laser stimuli. While electrical stimuli to the affected areas induced evoked potentials and SSRs of normal latency and amplitude, CO2 laser stimulation induced absent or abnormally reduced evoked potentials. Also, warmth and heat pain stimulation with a Peltier thermode induced absent or abnormal SSRs when applied over the affected areas but well defined SSRs when applied to the corresponding contralateral areas. Our results reveal the utility of recording the SSR to pain and temperature stimuli over specific body sites to demonstrate impairment of pain and temperature pathways in patients with syringomyelia. Comparison of electrical versus laser and temperature induced SSRs is an objective means to evaluate the selective thermoalgesic sensory deficit in these patients.

Prepulse inhibition of the blink reflex by laser stimuli in normal humans.

The subcortical integrative effects of laser-induced activation of pain ascending tracts were examined in 11 healthy volunteers, aged 22-52 years. Subjects underwent either CO2 laser stimulation at the dorsum of the hand, electrical stimulation of digital nerves at the 3rd finger, or mechanical taps to the first dorsal interosseous space, preceding a blink reflex elicited by a supraorbital nerve electrical stimulus. The percentage inhibition induced in the R2 response of the blink reflex was similar for the three different stimulus modalities, but occurred at a different time interval. Compared to control trials, the R2 response of the test trials was a mean of 23.1% at the interval of 250 ms with laser stimuli, 17.4% at the interval of 100 ms with electrical stimuli to the 3rd finger, and 20.6% at the interval of 90 ms with a mechanical tap to the 1st interosseous space. Activation of pain receptors induces prepulse inhibition of the blink reflex at a delay corresponding to a slowly conducting pathway. The percentage inhibition is similar to that observed with other somatosensory inputs.

Effects of a startle on heart rate in patients with multiple system atrophy

The patient cooperation usually required for neurophysiological assessment of autonomic cardioregulatory function is difficult to obtain from patients with bradykinesia. A particularly interesting condition occurs in multiple system atrophy (MSA), which features both bradykinesia and autonomic dysfunction. Another characteristic of patients with MSA is their normal motor reaction to a startling stimulus. We used startle as a stimulus for testing autonomic cardioregulatory function in patients with MSA, thus avoiding the need for patient cooperation. In 10 healthy volunteers and 8 MSA patients, we recorded the electrocardiographic QRS complex with surface electrodes attached over the chest and delivered an acoustic startle stimulus after 8 seconds of baseline recording. We calculated the ratio between the pre‐stimulus and the post‐stimulus heart beat intervals (R–R ratio) by dividing the mean prestimulus R–R interval by the shortest R–R interval obtained within 10 seconds poststimulus. Healthy volunteers had a significant shortening of the R–R interval. The peak of the effect occurred after 2 to 5 seconds, with a mean R–R ratio of 1.14 (S.D. = 0.09). In contrast, R–R shortening was markedly reduced in patients, even though they had a normal motor response. The mean R–R ratio in patients was 1.03 (S.D. = 0.03), significantly lower than in healthy volunteers (P < 0.01). Our results demonstrate an abnormally reduced modulation of the heart beat frequency in patients with MSA, compatible with a dysfunction on pathways responsible for autonomic regulation. The method described here may be useful in the assessment of cardioregulatory function in poorly cooperative patients with normal startle responses.

Laser evoked potentials and prepulse inhibition of the blink reflex in patients with Wallenberg's syndrome

&NA; Spinothalamic tract lesions in patients with Wallenbergs syndrome can be demonstrated by abnormalities in the laser evoked potentials (LEPs) to stimulation of the affected side. However, before reaching the structures generating LEPs, laser stimuli can induce effects at a subcortical level. We examined LEPs and laser‐induced prepulse inhibition of the blink reflex in seven patients with Wallenbergs syndrome within a month after the infarct. All patients had abnormally elevated thresholds for temperature and pain sensation, and for pinprick pain induced by laser stimuli, in the affected vs the non‐affected side. LEPs to stimulation of the affected side were abnormal because of absent, reduced or delayed responses. However, the same laser stimuli that were unable to induce LEPs generated normal inhibition of the blink reflex response when applied 250 ms before a trigeminal nerve electrical stimulus. The percentage inhibition induced in the R2 response of the blink reflex by laser stimulation of the affected side was not different from that induced by stimulation of the non‐affected side, or in control subjects. These results are compatible with either a different pathway for prepulse inhibition and evoked potentials or a reduced energy requirement of the sensory input generating prepulse inhibition in comparison to that generating evoked potentials.

Evaluation of afferent pain pathways in adrenomyeloneuropathic patients

OBJECTIVE Patients with adrenomyeloneuropathy may have dysfunctions of visual, auditory, motor and somatosensory pathways. We thought on examining the nociceptive pathways by means of laser evoked potentials (LEPs), to obtain additional information on the pathophysiology of this condition. METHODS In 13 adrenomyeloneuropathic patients we examined LEPs to leg, arm and face stimulation. Normative data were obtained from 10 healthy subjects examined in the same experimental conditions. We also examined brainstem auditory evoked potentials (BAEPs), pattern reversal full-field visual evoked potentials (VEPs), motor evoked potentials (MEPs) and somatosensory evoked potentials (SEPs). RESULTS Upper and lower limb MEPs and SEPs, as well as BAEPs, were abnormal in all patients, while VEPs were abnormal in 3 of them (23.1%). LEPs revealed abnormalities to stimulation of the face in 4 patients (30.7%), the forearm in 4 patients (30.7%) and the leg in 10 patients (76.9%). CONCLUSIONS The pathologic process of adrenomyeloneuropathy is characterized by a preferential involvement of auditory, motor and somatosensory tracts and less severely of the visual and nociceptive pathways. This non-inflammatory distal axonopathy preferably damages large myelinated spinal tracts but there is also partial involvement of small myelinated fibres. SIGNIFICANCE LEPs studies can provide relevant information about afferent pain pathways involvement in adrenomyeloneuropathic patients.

ID 252 – Auditory startle reflex (ASR) in ischemic and hemorrhagic stroke

Objective To evaluate the influence of cortical and subcortical vascular lesions on ASR. Methods We studied in 16 patients (9 middle cerebral artery (MCA) lesions and 7 basal ganglia hematoma (BGH)): ASR, MEP, cortical silent period, H reflex and Fugl-Meyer and Ashworth scale. Six were evaluated in the acute phase, 6 in subacute and chronic phases and 4 in both. Results Four of 5 BGH patients evaluated in the acute phase had an absent ASR and one responded only on the clinically spared side. On the contrary, four of 5 MCA patients evaluated in the acute phase presented an increased biceps response on the clinically affected side (CAS). In subacute and chronic phases 3 of 5 MCA and 4 of 5 BGH patients developed enhanced biceps responses on the CAS. Conclusions Enhanced ASR in vascular lesions can be due to a loss of the inhibitory hemispheric or basal ganglia drive on ASR generators. The absence of ASR in the acute phase of BGH could suggest a transient hypofunction of brainstem structures. Key message Ischemic stroke can be associated with an increased ASR on the CAS and BGH with an absent ASR in the acute phase, which is enhanced in subacute and chronic phases.

P820: Withdrawal reaction in response to a single nociceptive stimulus in myelopathy

bers is strongly recommended to gain better knowledge and understanding of autistic children’s hearing and behavior patterns References: [1] Ceponiene R, Cheour M, Naeaetaenen R. Interstimulus interval and auditory event-related potentials in children: evidence for multiple generators. Electroenceph. Clin Neuroph. 1998; 108: 345-354 [2] Sininger YS, Abdala C. Physiologic assessment of hearing. In: Lalwani A, Grundfast KM, editors. Pediatric Otology and Neur. Phi. (PA): LippincottRaven Publ.; 1998. p. 127-154.

12. The importance of neurophysiological studies in the diagnosis of orthostatic tremor

muscles expected to react and decreased in others such as, for instance, the homonymous muscles of the contralateral side. The contrast between the increase and decrease of excitability in homonymous muscles is likely much more marked in SRT than in CRT. We reasoned that, if inhibition is not fully accomplished, some remaining activity would be seen in the muscles not to be responding in a StartReact paradigm using SRT and CRT. Subjects and methods: In 11 volunteers, we studied the EMG and movement occurring in the forearm muscles of the side contralateral to the one requested to react in SRT and CRT. In 25% of the trials, the IS was accompanied by a SAS. Results: As expected, reaction time was shorter for trials with SAS than for trials without SAS. This was the case for both, SRT and CRT although the percentage shortening was significantly less for CRT. In no-SAS trials, contralateral activity was absent in SRT, 4% of trials in ART and 18% of trials in CRT. In SAS trials, contralateral activity was seen in 52% of the trials in SRT, in 61% in ART and in 79% in CRT. Conclusions: The difference between SAS and no-SAS trials in contralateral EMG activity may be explained by the fact that SAS causes precipitated execution preventing the inhibitory action to be fully implemented. Contralateral hand activity could also be a startle-related response but the fact that it is seen in a significant number of trials with no SAS and the fact that it takes a distribution of the triphasic pattern in a few cases makes it unlikely.