Ricerc@Sapienza

We thank Lumsden and colleagues for their comments on ourpaper ‘‘Spastic dystonia in stroke subjects: prevalence and featuresof the neglected phenomenon of the upper motor neuron syn-drome” (Trompetto et al., 2019). We agree with them that preciseterminology is essential for unambiguous communication andsharing of knowledge. Since this goal is far from being achievedin the field of the positive phenomena of the upper motor neuronsyndrome (UMNS), we agree that the time has come to find anomenclature able to capture the essential and unique featuresof the phenomenon so far reported as ‘‘spastic dystonia”, therebyeliminating eventual confusion. Realistically, this should be matterof dedicated reflections, but we welcome the opportunity offeredby Lumsden and colleagues (Lumsden et al., 2019).The main points of the subject (and debate) are the following.First, the currently used term ‘‘spastic dystonia” refers to theinability of patients with UMNS to voluntary silence muscle activ-ity on command (Gracies, 2005; Sheean and McGuire, 2009;Trompetto et al., 2014). This inability leads to spontaneous tonicmuscle contractions, which prove stretch-sensitive (Gracies,2005), and ultimately amplify the velocity-dependent hypertonia(Marinelli et al., 2017; Trompetto et al., 2019Trompetto et al., 2019).Second, as an inability to relax muscles at will, the phenomenonfalls in the most recent definition of dystonia, ‘‘a movement disor-der characterized by sustained or intermittent muscles contrac-tions causing abnormal, often repetitive, movements, postures, orboth” (Albanese et al., 2013).Third, since ‘‘spastic dystonia” may occur in the absence ofvelocity-dependent hypertonia (Denny-Brown, 1966), which isthe hallmark of spasticity, why qualifying this phenomenon as‘‘spastic”? But: if this is not ‘‘spastic”, should it be simply ‘‘dysto-nia”, ‘‘secondary dystonia”, or ‘‘dystonia in the context of theUMNS”?As delineated above, the debate prompts comments that movefrom the phenomenological to the pathophysiological level. Weshortly review strengths and weaknesses for each point, and post-pone eventual solution to more thorough review.From a phenomenological point of view, we consider as undis-puted that dystonia and ‘‘spastic dystonia” manifest similarly,therefore the involuntary muscle activity we are dealing with isdystonic in nature. But it is only one nature of the abnormal move-ment, the second one being its exquisite sensitivity to musclelengthening.Equally undisputed is the clearly distinct pathophysiologybetween ‘‘dystonia” and ‘‘spastic dystonia”. The overwhelmingmajority of papers using the term ‘‘dystonia” refers to clinical con-ditions stemming from structural or functional diseases of thebasal ganglia, unrelated to the activity of the stretch reflex. Onthe contrary, ‘‘spastic dystonia” is found in patients having lesionsoutside the basal ganglia, exhibiting clear abnormality in theexcitability of the stretch reflex circuitry. Because definitely dis-tinct pathological mechanisms give rise to muscle overactivitysharing similar phenomenology, the term ‘‘dystonia” seems inade-quate for describing the involuntary muscle contraction we aredealing with.Even from a nosological perspective, the term ‘‘dystonia”appears inappropriate. By definition, ‘‘dystonia” is amovement dis-order, whereas ‘‘spastic dystonia” is not. Indeed, amovement disor-der(meaning to indicate a disease of the basal ganglia) is definedas a ‘‘neurological syndrome in which there is either an excess ofmovement or a paucity of voluntary and automatic movements,unrelated to weakness or spasticity” (Fahn et al., 2011). It is apod-ictic how much ‘‘spastic dystonia” can be related to both weaknessand spasticity. Corollary is that spastic dystonia can neither beconsideredtout-court‘‘a