A hereditary haemorrhagic telangiectasia family with pulmonary involvement is unlinked to the known HHT genes, endoglin and ALK-1.
(1/231)
BACKGROUND: Pulmonary arteriovenous malformations (PAVMs) occur in over 25% of patients with the autosomal dominant disorder hereditary haemorrhagic telangiectasia (HHT). Mutations in two genes, endoglin and ALK-1, are known to cause HHT. Each encodes a protein expressed on vascular endothelial cells and involved in signalling by members of the transforming growth factor (TGF)-beta superfamily. To date, PAVMs have not been detected in ALK-1 families. There is evidence from a single HHT family without pulmonary involvement that a third HHT gene may exist. To establish the existence of a further HHT gene responsible for PAVMs, linkage analyses were performed on an expanded PAVM-HHT family in which HHT did not result from endoglin mutations. METHODS: Family members were assessed clinically to assign HHT disease status and were screened for PAVMs. DNA was extracted from blood obtained from 20 individuals of known disease status. Short tandem repeat polymorphic markers spanning the intervals containing the endoglin and ALK-1 genes were amplified by the polymerase chain reaction using (33)P-labelled oligonucleotide primers, separated by denaturing polyacrylamide gel electrophoresis (PAGE), and the resultant autoradiographs were examined for allele sizes. Linkage analyses were performed using MLINK and GENEHUNTER. RESULTS: Twelve members spanning four generations were affected with HHT. Two had proven PAVMs, one with a classical appearance, the other exhibiting microscopic PAVMs exacerbated by pregnancy. Two point lod and multipoint lod scores significantly excluded linkage to endoglin and ALK-1 in this pedigree. CONCLUSIONS: This study confirms the existence of a third HHT locus that accounts for disease in some HHT patients with pulmonary involvement. (+info)
Abnormal premovement gating of somatosensory input in writer's cramp.
(2/231)
One characteristic of focal dystonia is the sensory trick, by which sensory input to a certain area of the body can reduce abnormal contractions in muscles nearby. This suggests that adjusting the link between sensory input and movement allows motor commands to be issued more effectively from the brain. To explore this sensorimotor link, we studied the attenuation (gating) of somatosensory evoked potentials (SEPs) before and during hand movements in patients with writer's cramp. For premovement gating, 10 patients and 11 age-matched normal subjects were given a warning sound followed 1s later by an electric stimulus to the right median nerve at the wrist. The latter served both as a reaction signal to start a finger extension task and as the input to evoke SEPs over the scalp. Because reaction times always exceeded 70 ms, short-latency SEPs thus obtained were unaffected by the afferents activated by the movement. The amplitudes of frontal N30 components were significantly decreased over the frontal leads compared with SEPs elicited at rest (P: < 0.002) in the normal group, whereas significant gating was found not for N30 but for frontal P22 (P: = 0. 002) in the patient group. For midmovement gating studies, SEPs to the right median nerve stimulation were recorded in 16 patients and 12 age-matched normal subjects at rest, and during active and passive finger extension-flexion movements. In contrast to the premovement SEPs, the frontal N30 was equally gated during active and passive movements both in the patient (P: < or = 0.002) and the normal group (P: < or = 0.003). These findings indicate that in writer's cramp the sensitivity of sensory input channels from the hand is wrongly set by the central command to move. Perhaps the sensory trick, by supplying additional input not usually present during unobstructed movement, is a manoeuvre to correct this imbalance. Dystonia may result not only from abnormalities in the central motor command but also from disturbed central processing of sensory input. (+info)
Hereditary juvenile-onset craniocervical predominant generalized dystonia with parkinsonism.
(3/231)
OBJECTIVE: To report a unique hereditary, juvenile onset, craniocervical predominant, generalized dystonia and parkinsonism affecting four members of one family. FAMILY DESCRIPTION: A father and three of his four daughters presented to us over the past 30 years with a similar picture of generalized dystonia, starting in the craniocervical region in the second or third decade of life. They later developed moderate parkinsonism, mainly manifesting bradykinesia, rigidity and abnormal postural reflexes. Biochemical and genetic tests excluded Wilson's disease, Huntington's disease and Oppenheim's dystonia. CONCLUSION: This is a new type of familial dystonia-parkinsonism where the craniocervical dystonic symptoms are most prominent in the early stages while parkinsonism becomes the predominant problem later in life. A search for the genetic mutation in this family is underway. (+info)
Unilateral lesions of the globus pallidus: report of four patients presenting with focal or segmental dystonia.
(4/231)
OBJECTIVES: To interpret clinical features after unilateral lesions of the globus pallidus on the basis of physiology of the basal ganglia. METHODS: Four patients with unilateral lesions in the globus pallidus (GP) were clinically examined and the literature on patients with pallidal lesions was reviewed. RESULTS: Three patients presented with contralateral dystonia largely confined to one arm in one case and one leg in two cases. One patient had predominant contralateral hemiparkinsonism manifested mainly as micrographia and mild dystonia in one arm. The cause of the lesions was unknown in two patients. In the other two symptoms had developed after head trauma and after anoxia. All lesions involved the internal segment of the GP. Two patients, including the patient with hemiparkinsonism, had additional involvement of the external segment of the GP. In the literature reports on 26 patients with bilateral lesions restricted to the GP only two with unilateral lesions were found. The patients with bilateral pallidal lesions manifested with dystonia, parkinsonism, or abulia. One of the patients with unilateral GP lesions had contralateral hemidystonia, the other contralateral arm tremor. CONCLUSION: These cases emphasise the importance of the GP, particularly its internal segment, in the pathophysiology of dystonia. (+info)
Computational model of the role of sensory disorganization in focal task-specific dystonia.
(5/231)
We present a new computational model for the development of task-specific focal dystonia. The purpose of the model is to explain how altered sensory representations can lead to abnormal motor behavior. Dystonia is described as the result of excessive gain through a sensorimotor loop. The gain is determined in part by the sensory cortical area devoted to each motor function, and behaviors that lead to abnormal increases in sensory cortical area are predicted to lead to dystonia. Properties of dystonia including muscular co-contraction, overflow movements, and task specificity are predicted by properties of a linear approximation to the loop transformation. We provide simulations of several different mechanisms that can cause the gain to exceed 1 and the motor activity to become sustained and uncontrolled. The model predicts that normal plasticity mechanisms may contribute to worsening of symptoms over time. (+info)
Sporadic paroxysmal exercise induced dystonia: report of a case and review of the literature.
(6/231)
Sporadic paroxysmal exercise induced dystonia (PEID) is a rare condition. So far only fifteen cases have been reported in the world literature. It is characterised by dystonic posture on prolonged exercise, which gets relieved with rest. In general, these are refractory to medical treatment. We report one such case, along with review of the literature. The lower limbs were spared and only right shoulder was tucked up with the head turning to right side. The duration of exercise necessary to bring out the dystonic posture gradually diminished with time, a feature not reported previously. (+info)
Abnormalities of sensorimotor integration in focal dystonia: a transcranial magnetic stimulation study.
(7/231)
It has been postulated that sensorimotor integration is abnormal in dystonia. We investigated changes in motor cortical excitability induced by peripheral stimulation in patients with focal hand dystonia (12 patients with hand cramps) and with cervical dystonia (nine with spasmodic torticollis) compared with 16 age-matched normal controls. Motor evoked potentials (MEP) to focal (figure-of-eight coil) transcranial magnetic stimulation of the hand area were recorded from the right abductor pollicis brevis (APB), first dorsal interosseus (FDI), flexor carpi radialis and extensor carpi radialis muscles. Changes of test MEP size following conditioning stimulation of the right median nerve (or of the index finger) at conditioning-test (C-T) intervals of 50, 200, 600 and 1000 ms were analysed. Peripheral stimulation significantly reduced test MEP size in the APB and FDI muscles of normal control and spasmodic torticollis patients. The inhibitory effect was larger upon median nerve stimulation and reached a maximum at the C-T interval of 200 ms. On the contrary, hand cramp patients showed a significant facilitation of test MEP size. This study suggests that MEP suppression following peripheral stimulation is defective in patients with focal hand dystonia. Central processing of sensory input is abnormal in dystonia and may contribute to increased motor cortical excitability. (+info)
Wilson's disease presenting in a family with an apparent dominant history of tremor.
(8/231)
A patient with Wilson's disease is described who presented with dystonic tremor in a family with an apparent dominant history of tremor. Subsequent investigation showed that the patient's mother had essential tremor, with molecular analysis of the ATP7B gene excluding the possibility of pseudodominant inheritance. This case highlights the importance of considering the possibility of Wilson's disease in every young patient with a movement disorder, even where the clinical picture does not suggest a recessively inherited disorder. (+info)