Before describing an organ of the body's anatomy with the appropriate scientific terms, it is necessary to be clear about the meaning that is given to it, it is necessary to know where and why it is called in the corresponding way and what this term ultimately means. In the following case we have the thalamus. This word originates from the Latin thalamus, and this in turn from ancient Greek. It is the wedding site, the bedroom, the conjugal bed.
Thus we see that the origin of this term is within the ancient Greek culture. Many of these old words are called old reintroduced, that is to say, these are words that were used in antiquity (XNUMXth century BC to XNUMXth century AD) but that in the dark course of the Middle Ages were lost and were reincorporated into the scientific vocabulary during the Renaissance, at which time the lost classical Greek and Latin texts are rescued.
What is the thalamus?
The first medical references to the term thalamus are traced back to texts from 1664 with reference to the optic nerves; also in texts from the year 1756. However, the legendary Hippocrates (129th century BC) and Galen (Pergamum, present-day Turkey, 216-XNUMX) used the term to identify the cerebral ventricle, to refer to the so-called optic thalamus.
There are other references that connect the termor with religion, it is the site of the oracles in the temple. Also in botany it is identified as a part of the flower. And in literature the metaphorical indications of the term abound.
The thalamus is an organ present in the brain organization of the vertebrate animal kingdom, with its various differences from one species to another. Now, in the concrete situation of human anatomy, an important region of the brain is called the thalamus. It constitutes a large structure located in the center of the brain, it has two huge oval parts that play an important role in sensory filtering, these two structures are linked by the interthalamic connection.
The thalamus too it is subdivided into 80 neuronal nuclei. It is also known as a fundamental part of the diencephalon. The latter is located in the cerebral cortex and the upper part of the brain stem, residing in all the lobes of the brain. The diencephalon is made up of the thalamus, the hypothalamus (located under the first) and other smaller parts.
Modular
Structurally, three types of nuclei can be described in this neuronal crowding of the brain gray mass:
- Specific connection cores. Which send sensory data to specific areas of the cerebral cortex specialized in processing the data that arrive in a specific direction.
- Nonspecific connection nuclei. They send information to very wide areas of the cerebral cortex without establishing differentiations or discriminations of a specific type.
- Association nuclei. It constitutes an information circuit that connects the cerebral cortex with subcortical structures.
They can be spoken of thalamic zones that in turn can also be subdivided for study:
- Previous territory: anterior nucleus (NA)
- Ventral territory: anterior ventral nucleus (VA), lateral ventral nucleus (VL), posterior ventral nucleus (VP): ventral posteromedial (VPM) and ventral posterolateral (VPL)
- Rear territory: pulvinar and geniculate (medial and lateral)
- Medial territory: medianodorsal nucleus (MD), centromedial nucleus (CM)
- Back territory: dorsal lateral nucleus (LD), posterior lateral nucleus (LP)
- Other territories: intralaminar nuclei (located in the central medullary lamina),
- Thalamic reticular nuclei (they rest on the weft of fibers that surround the thalamus).
Neurons
Going into the neural details we see that the thalamus is a combination of many substructures with specialized functions, all are, in short, neurons and glial cells. Like any other part of the brain, the thalamus is only right if it is connected to other areas of the nervous system, and this is reflected in the type of neurons that compose it.
The types of neurons in the thalamus are as follows
- Local interneurons. These are specifically responsible for making the information that arrives from other parts of the nervous system processed in the thalamus, transforming it into a new series of data. Therefore, its main function is to send nerve impulses to other interneurons in the thalamus. They make up 25% of the neurons in the thalamus.
- Projection neurons. These are responsible for sending information to the outskirts of the thalamus, towards the cerebral cortex. They constitute 75% of thalamic neurons.
Thalamus functions
The basic functionality of the thalamus is as follows: in the first place, it is responsible for integrating all sensory information directed to the cerebral cortex. From there it assumes a transmitting role, spreading most of the information that reaches that part of the brain, apart from integrating all sensory modalities, enabling or inhibiting projections towards some lobes or other sites.
It is important to take into account the importance of the thalamus for the maintenance of cortical activity. Do not forget that it is also responsible for transmitting information from the cerebellum and the striatum to the cerebral cortex.
These two are the centers that modulate the descending motor pathways of the cerebral cortex. In short, almost the entire sensory motor information it transits the thalamus before arriving at its destination, the cortex. It also regulates sleep, alertness, and wakefulness.
Thalamic pathologies
Knowing then the functions we could identify the damages or affections to the thalamus. Damages or accidents to the thalamus can occur due to: neoplasms, degenerative damage, ischemia, bleeding injury, trauma.
Pathological studies of the effects of thalamic lesions deal with sensorimotor, cerebellar, bilateral oculomotor disorders and dementia. Disturbances in speech and memory, confusion in attention, and hemineglect stand out. Lesions on the left thalamus are expressed in language disturbances In contrast, injuries to the right thalamus create defects such as motor reluctance and left hemiinattention. Now thalamic lesions do not always have repercussions in cognitive alterations, in many cases when they appear frequently they are transitory. Bilateral thalamic disease is the cause of mutism and dementia.
The signs and symptoms of thalamic damage are:
- Sensory loss: Injury to the ventral posteromedial and posterolateral nuclei (VPL and LP) causes loss of all forms of sensation, including fine touch, tactile localization and discrimination, and muscle and joint proprioception on the opposite side of the body.
- Thalamic pain: After a thalamic injury, many sensations are interpreted as spontaneous and excessive pain that occurs on the opposite side of the body, in response to mild stimuli.
- Abnormal involuntary movements: Choreoathetosis with ataxia may occur. Ataxia can arise as a result of loss of muscle proprioception and joint movement caused by injury.
- Thalamic hand: Wrist pronation and flexion, metacarpophalangeal flexed and interphalangeal extended, fingers can be actively moved, but they are slow.
- Pusher patient: Due to injury to the VPL and LP nuclei. Patients push toward the affected side using extensor activity on the less affected side.
Thalamic functions can be affected by many conditions. These include stroke, injury, and tumors. Other pathologies or diseases that affect the thalamus and balance they are muscular dystrophy, Parkinson's and Hutchinson's disease. These circumstances explain the nerve channels in the thalamus that break down, interrupt or slow down the information in it.
Diagnosis
Imaging is necessary to see any damage to the thalamus. The nuclear magnetic resonance (NMR) y computed tomography (CT), these are most often used when examining the soft tissue of the brain.
La Positron Emission Tomography (PET) It is an excellent diagnostic tool. By these three diagnoses, any type of abnormality in the shape, size and density of the thalamus that is indicative of damage or disease can be captured.
Thalamic pain syndrome treatment
The symptoms of thalamic pain syndrome may improve over time, however, more often, the syndrome and the pain associated with it is persistent. Therefore, the duration of treatment is very long and trial and error is the only way to go towards a cure. Due to the nature of pain, pain relievers are not strong enough to cause any significant and definitive relief.
Therefore, pain relievers are often combined with other drugs. In severe cases, where the pain is unbearable, the options for managing it may be diverse, such as the pumps that implanted directly into the spinal cord to medicate, the surgical destruction of a portion of the thalamus, or deep brain stimulation.
Now, these treatments do not guarantee absolute results, those obtained and the degree of relief is different for the different patients who undergo these treatments. As difficult as the treatment is also establishing a diagnosis of thalamic pain syndrome. This is usually done by an experienced neurologist who has already treated many stroke patients