[Essential tremor: a review of pathogenic mechanisms]. / Temblor esencial: una revisión sobre sus mecanismos patogénicos.

INTRODUCTION: Essential tremor (ET) is the commonest involuntary movement observed and is seen when a given posture is maintained. Although it does not affect life expectancy, it may cause considerable functional disability and serious psychological effects in the affected person. DEVELOPMENT: ET is a heterogeneous clinical condition. Its physiopathology is still not known, is very complex and involves many mechanisms, both structural and biochemical, although as yet there is no theory to include them all. In view of what is known at present, it may be accepted that there is a central oscillator at olive-cerebellar-thalamic-cortical-spinal level, which is the primary generator of ET, modulated by a peripheral component. The tremor results from interaction between increased central excitability and peripheral regulation, which in turn reinforces the central overactivity. It may also be that the monoaminergic system (catecholaminergic and serotoninergic), adrenoreceptors (especially the B2 muscular adreno-receptors) and the bodily structure itself, amongst other factors, may influence the pathogenic mechanism of ET. It is likely that there is a multifactorial genetic disorder which predetermines this physiopathogenic process, although this has not yet been determined. CONCLUSIONS: In this paper we review the various hypotheses and existing knowledge related to the aetiopathogenesis of TE.

[A review of the pathogenesis of the hallucinatory state. A description of four case]. / Revisión sobre la patogenia del estado alucinatorio. Aportación de 4 casos.

INTRODUCTION: A hallucination is a sensorial experience occurring in the absence of external stimuli. It may show as psychological or organic disorders. The main causes are lesions of the central nervous system and of the sensorial organs. The hallucination may present with or without critical perception but always appears to be a real experience. CLINICAL CASE: We describe four patients diagnosed as having hallucinations secondary to known lesions. The first two had visual hallucinations and cerebral ischaemia, the first in the dorso-lateral region of the medulla oblongata and the second in the left parietal lobe. The other two had peripheral sensorial defects. The third patient had simultaneously an ophthalmic disorder and visual hallucinations, and the fourth had chronic hypoacusia and auditory hallucinations. All showed structured sensorial hallucinations with critical appraisal of these hallucinations. CONCLUSIONS: In this paper we review the pathogenesis of the organic hallucinatory state. The main mechanisms are proposed: by means of liberation (destruction of inhibitory structures) and by means of irritation (anomolous excitation of cerebral structures). Also we point out the difference between a hallucination and psychiatric disorders, mainly in three aspects: presence of the known organic lesion, critical appraisal of the perception in spite of it appearing as real to the patient, and the absence of associated psychiatric pathology.

[Biopercular lesion with inverse dissociation]. / Lesión biopercular con disociación inversa.

Foix-Chavany-Marie Syndrome or anterior opercular syndrome constitutes the cortical form of pseudobulbar palsy. Its most common etiology is stroke in the region of either operculum. Clinically it can be characterized by severe dysarthria and facio-pharyngo-glosso-masticatory dysplasia with automatic-voluntary dissociation. An inversion of this classical dissociation can be seen in patients with emotional paralysis in the face, in whom asymmetry of emotional expression but conservation of voluntary movement can be seen. The lesional topography of this inverse dissociation corresponds to the supplementary motor area. both processes support the existence of an anatomical base which is different for emotional movements and voluntary types. We describe the clinical case of a 65 year old woman with a history of breast cancer who presented a subacute and progressive clinical picture of dysphagia and severe dysarthria. Upon neurological examination slight velo-palato-pharyngea was noticed; most relevant was paralysis of the facial muscles for either emotional or automatic movements while voluntary innervation was maintained. Neuroradiological studies show the presence of brain metastasis located in both Roland opercula. Although the neuroanatomic bases for automatic-voluntary dissociation remain unclear, our case lends weight to the evidence that impulses for voluntary and emotional movements originate in different cortical areas or else take a different route through the brain. We have been unable to find any cases of biopercular lesion with inverse dissociation described in the literature we reviewed.

[Thyroid ophthalmopathy ad a unique clinical manifestation of thyrotoxicosis]. / Oftalmopatia tiroidea como unica manifestación clínica de tirotoxicosis. Presentación de cuatro casos.

Thyroid ophthalmopathy (TO) or Graves ophthalmopathy embraces a broad range of eye abnormalities which up to 90% of patients with hyperthyroidism (HT) are affected with. In some 10% of TO patients, this may begin oligosymptomatically, often with double vision and with neither clinical nor biochemical signs of thyroid disease. It is imperative to carry out a differential diagnosis with countless other causes for double vision and other eye socket processes. Ophthalmopathy may also occur in patients with hypothyroidism and for this reason some authors prefer to refer to it as dysthyroid orbitopathy. We present four cases of TO in which double vision was the first clinical sign of TO which in one case became severe, in two cases preceded hyperthyroid symptomatology and in the remaining case happened after hyperthyroidism had been corrected. The most valuable diagnostic test was orbit computerised tomography (CT) scan, which proved positive in all cases, and that, along with clinical tests and thyroid function data, confirmed a diagnosis of TO. All initially improved with corticosteroids although none completely regained eye movement during the time they were under supervision. The same happens in about 50% of patients who do not respond to treatment either with corticosteroids or with radiotherapy, and response is usually incomplete in those who do so respond.