US complements neurophysiological assessment even in routine practice, and this confirms the increasing interest in US for a multidimensional evaluation of peripheral nerve system diseases.
The reported incidence of pregnancy-related carpal tunnel syndrome (PRCTS) ranges from 0.8% to 70%, and little is known of its natural history. We systematically reviewed the reported incidence of PRCTS and evaluated its natural history. We identified 214 studies that fulfilled our selection criteria. Six publications fulfilled the inclusion criteria. Five fulfilled the incidence criteria, 3 fulfilled the natural history criteria, and 2 of the 6 publications satisfied both. The reported incidence of neurophysiologically confirmed PRCTS ranged from 7% to 43%, whereas the incidence of clinically diagnosed PRCTS ranged from 31% to 62%. Symptoms persisted in more than 50% of the patients after 1 year and in about 30% after 3 years. Our review suggests that variations in the reported incidence of PRCTS largely depend on the methods used to detect this syndrome. Our data also suggest that symptoms persist in a substantial number of patients 1 or more years after delivery.
Much evidence suggests that restless legs syndrome (RLS) is a disorder characterized by an unsuppressed response to sensory urges due to abnormalities in inhibitory pathways that specifically link sensory input and motor output. Therefore, in the present study, we tested sensory-motor integration in patients with RLS, measured by short latency afferent inhibition (SAI) and long latency afferent inhibition (LAI). SAI and LAI were determined using transcranial magnetic stimulation before and after 1 month of dopaminergic treatment in RLS patients. Ten naïve patients with idiopathic RLS and ten healthy age-matched controls were recruited. Patients with secondary causes for RLS (e.g. renal failure, anaemia, low iron and ferritin) were excluded, as well as those with other sleep disorders. Untreated RLS patients demonstrated deficient SAI in the human motor cortex, which proved revertible toward normal values after dopaminergic treatment. We demonstrated an alteration of sensory-motor integration, which is normalized by dopaminergic treatment, in patients affected by RLS. It is likely that the reduction of SAI might contribute significantly to the release of the involuntary movements and might account for the sensory urge typical of this condition.
In the present work, we aimed at assessing whether patients with idiopathic restless legs syndrome (RLS) showed alterations of sensory-motor plasticity, an indirect probe for motor learning, within the motor cortex (M1). Previous findings suggest that learning in human M1 occurs through LTP-like mechanisms. To test our hypothesis, we employed the paired associative stimulation (PAS) protocol by transcranial magnetic stimulation (TMS), which is able to induce LTP-like effects in the motor cortex of normal subjects. Twelve patients with idiopathic RLS and 10 age- and sex-matched control subjects were recruited. PAS protocol consisted of 0.05 Hz electrical median nerve stimulation (90 stimuli), paired with 0.05 Hz TMS (90 stimuli) over the hot spot for stimulating the abductor pollicis brevis (APB) muscle given 25 milliseconds after the onset of the electrical stimulus. Corticospinal excitability recorded in APB muscle, as indexed by MEP obtained after single stimulus, was tested before and up to 30 minutes after PAS protocol. Eight of 12 patients were studied before and after 4 weeks of dopaminergic treatment. PAS protocol increased significantly corticospinal excitability as long as 30 minutes in healthy subjects. On the contrary, PAS protocol did not change the amplitude of MEPs in patients with idiopathic RLS without treatment. PAS associative plasticity was restored after 4 weeks of dopaminergic treatment. Our data demonstrated that associative sensory-motor plasticity, an indirect probe for motor learning, is impaired in idiopathic RLS patients but may be reverted to normal after dopaminergic treatment.
US is becoming an invaluable tool for diagnosing peripheral nerve entrapments. The current cases suggest that nerve US should be strongly considered as an adjunctive diagnostic tool for nerve palsies developing after trauma.
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