Thalamic syndrome: symptoms, causes and treatment

The thalamus is a brain structure that serves as a junction point for multiple neural pathways (it is a “center of relief”). His injury caused thalamic syndrome, A clinical picture that triggers several symptoms, with a predominance of thalamic pain.

Here, we will know in detail the causes of this syndrome, as well as its symptoms and possible treatments.

    the thalamus

    The thalamus is a brain structure; it is a central gray nucleus at the base that serves as a junction point for several neural pathways. It is a uniform structure, located on either side of the third ventricle. It occupies about 80% of the diencephalon and is divided into four main sections (anterior, medial, lateral and posterior), themselves divided into several nuclei.

    All the sensory and sensory pathways that arise in the spinal cord, brainstem and hypothalamus converge in the thalamus, where they emboss (this is a “center of relief)”. In addition, the various coordination channels of the system are added. Extrapyramidal, vestibular nuclei, cerebellum, striated nuclei and cerebral cortex.

    Thalamic syndrome: characteristics

    Thalamic syndrome, also called Déjerine-Roussy syndrome, is characterized by the following symptoms: transient mild hemiparesis, hemicoreoathetosis, hemihypoaesthesia, hyperalgesia, Allodynia and hemiataxis with asterognosia of varying intensity. This syndrome occurs with lesions of the posterior nuclei of the thalamus.

    The clinical manifestations produced by thalamic lesions are very diverse (since they cover many pathways), not very systematic, relatively infrequent and little known to the clinician, although we can specify them, as we will see later.

    This syndrome was first described in early 1903, when Jules Joseph Dejerine and Gustave Roussy studied the clinical and pathological facts of thalamic syndrome. His original description of thalamic syndrome remains to this day, and little change has been added to it over the past 100 years, although Lhermitte in 1925 and Baudouin in 1930 made important contributions to defining the characteristics of thalamic hemorrhage. .

    On another side, Fisher focused on language disorders and eye motility disorders produced by thalamic lesions.

    Thus, twenty years after this first description, Foix, Massson and Hillemand, other researchers, showed that the most common cause of the syndrome was obstruction of thalamogenic arteries (Branches of the posterior cerebral artery).

    symptoms

    The most distressing symptom of thalamic syndrome is pain; it is generally intractable, intense, debilitating and constant pain. Thalamic pain is of central origin, that is, its origin is in the cerebral cortex.

    The pain is also intractable and unpleasant and is resistant to pain relievers.. Pain usually presents as an initial symptom in 26-36% of patients. The sensation of pain is a burning and tingling sensation, and is usually associated with painful hyperesthesia in the same distribution. This hyperesthesia is defined as an exaggerated sensation of tactile stimuli (such as the sensation of tingling).

    Other prominent symptoms of thalamic syndrome are paresthesia, mild transient hemiparesis, hemicoreoathetosis, hemi-hypoaesthesia, hyperalgesia, allodynia, and hemiataxia with asterognosia of varying intensity.

    Specifically, patients with this syndrome manifest sensory loss contralateral to the lesion in all modalities. In addition, there are also vasomotor disorders, severe dysesthesia of the involved hemibody and sometimes choreoatetoid or ballistic movements.

    the causes

    The cause of thalamic syndrome is damage to the thalamus. More precisely, this injury involves the lower and lateral nuclei.

    The most common lesions of thalamic syndrome are of vascular origin (stroke), although there are lesions of a different nature as well, such as those of metabolic, neoplastic, inflammatory and infectious origin.

    On the other hand, alluding to the vascular origin of the syndrome, thalamic infarctions are generally due to occlusion of one of the four major vascular regions: Posterolateral, dorsal, paramedian and anterior.

    treatment

    Treatment of thalamic syndrome primarily involves the associated pain. Previously, treatment was based on neurosurgery, with procedures such as thalamotomy (removal of a small area in the thalamus), mesencephalotomies (removal of the midbrain), and cingulotomies (cingulate section).

    However, new neurosurgical treatments have been introduced, such as spinal cord stimulation, motor cortex stimulation, and chronic deep brain stimulation, using stereotaxic approach techniques.

    On the other hand, other new treatments have also been used in recent years, opiates, tricyclic antidepressants, and analgesics-antiepileptics (For example gabapentin).

    Bibliographical references:

    • Salazar-Zúñiga, A. and Carrasco-Vargas, H. (2006). Treatment of thalamic syndrome (Dejerine-Roussy) secondary to ischemic stroke, with gabapentin, report of four cases and review of the literature, Neurol Neurocir Psiquiat, 39 (2): 70-75.
    • De Betolaza, S., Núñez, M., and Roca, F. (2016). Thalamic injuries: a semiological challenge. Thalamic lesions: a semiological challenge. Uruguayan Journal of Internal Medicine, 1, 12-19.

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