Neuroanatomy, Thalamus


Article Author:
Tyler Torrico


Article Editor:
Sunil Munakomi


Editors In Chief:
Mohamed Hegazy
Najib Murr


Managing Editors:
Avais Raja
Orawan Chaigasame
Carrie Smith
Abdul Waheed
Khalid Alsayouri
Trevor Nezwek
Radia Jamil
Patrick Le
Anoosh Zafar Gondal
Saad Nazir
William Gossman
Hassam Zulfiqar
Hussain Sajjad
Steve Bhimji
Muhammad Hashmi
John Shell
Matthew Varacallo
Heba Mahdy
Ahmad Malik
Sarosh Vaqar
Mark Pellegrini
James Hughes
Beata Beatty
Beenish Sohail
Nazia Sadiq
Hajira Basit
Phillip Hynes


Updated:
5/17/2019 3:13:41 PM

Introduction

The thalamus is a mostly gray matter structure of the diencephalon that has many important roles in human physiology. The thalamus is composed of different nuclei that each serve a unique role, ranging from relaying sensory and motor signals, as well as regulation of consciousness and alertness. Clinically, there are only a few conditions related to thalamic damage and dysfunction. Most of these conditions are rare, but some of the more common conditions have significant anatomical changes that are visible with neuroimaging.  Surgical interventions of the thalamus in the past have had limitations, but currently, this field is evolving due to increased accessibility through the advancement of microsurgical techniques and improved neuroimaging.

Structure and Function

The thalamus is a paired gray matter structure of the diencephalon located near the center of the brain. It is above the midbrain or mesencephalon, allowing for nerve fiber connections to the cerebral cortex in all directions — each thalamus connects to the other via the interthalamic adhesion. The thalamus forms the upper and lateral walls of the third ventricle while the dorsal surface is part of the floor of the body of the lateral ventricle. Laterally, the thalamus limits with the posterior arm of the internal capsule. Anterolaterally, it limits with the head of the caudate and ventral nucleus with the subthalamus and hypothalamus.  

While the thalamus is mostly gray matter (cell bodies of neurons), there are some areas of white matter (axons). The external and internal medullary laminae are white matter structures of the thalamus. The external medullary laminae cover the lateral surface of the thalamus, and the internal medullary laminae divide the thalamic nuclei into anterior, medial, and lateral groups.[1]

The thalamus is made up of a series of nuclei which are responsible for the relay of the different sensory signals. These nuclei are formed mainly by neurons of excitatory and inhibitory nature. The thalamocortical neurons receive sensory, or motor information from the rest of the body and present selected information via nerve fibers (thalamocortical radiations) to the cerebral cortex. The thalamus also has connections with the hippocampus, mammillary bodies and fornix via mammillothalamic tract.[2] The connection of limbic system structures to the anterior nuclei of the thalamus allows the thalamus to be involved in learning and episodic memory.[3] The thalamus is also involved in the regulation of sleep and wakefulness.[4]

Generally, the thalamus acts as a relay station filtering information between the brain and body. Except for olfaction, every sensory system has a thalamic nucleus that receives, processes and sends information to an associated cortical area. The lateral geniculate nucleus of the thalamus receives visual sensory information from the retina to project to the visual cortex of the occipital lobe. The medial geniculate nucleus receives auditory sensory information from inferior colliculus and projects it to the primary auditory cortex in the temporal lobe. The ventral posterior nucleus of the thalamus is subdivided further by three. The spinothalamic tract is the sensory pathway for pain, temperature and crude touch that originates in the spinal cord and feeds into the ventral posterolateral nucleus of the thalamus for further processing.  While the ventral posteromedial nucleus receives sensory information from the trigeminal nerve about the face. Lastly, the ventral intermediate nucleus has correlations with pathological tremors.[5]

The reticular nucleus is in the ventral portion of the thalamus and forms a capsule around the thalamus laterally. Interestingly, this nucleus does not project to the cerebral cortex; rather, its function is to process and modulate information it receives from other thalamic nuclei. The reticular nucleus also receives disinhibitory input from the globus pallidus allowing for the initiation of voluntary movement.

Functionally, the thalamus divides into five major functional components as[6]:

  1. Reticular and intralaminar nuclei dealing with arousal and pain regulation
  2. Sensory nuclei regulating all sensory domains except olfaction
  3. Effector nuclei governing motor  language function
  4. Associative nuclei connoting cognitive functions
  5. Limbic nuclei encompassing mood and motivation

Embryology

During the third week of embryogenesis, the neural tube is created from the ectoderm. The neural tube forms the prosencephalon, the mesencephalon, and rhombencephalon. The prosencephalon is the most rostral of these structures and further divides into the telencephalon and diencephalon. The thalamus develops from the embryonic diencephalon.[7]

Blood Supply and Lymphatics

The basilar communicating artery, posterior cerebral artery, and posterior communicating artery are the major blood supply for the thalamus. The major vascular pedicles supplying the thalamus divide into[6]

  1. Tuberothalamic artery (polar artery)
  2. Paramedian artery
  3. Thalamogeniculate artery and 
  4. Medial and lateral posterior choroidal artery

Surgical Considerations

Due to the deep location of the thalamus, thalamic tumors have historically been difficult to manage. Recently contemporary microsurgical techniques and advances in neuroimaging have resulted in some improvement in outcomes of resections involving the thalamus.[8]

Clinical Significance

Though a central sensory relay station, thalamic lesions can paradoxically present with various non-sensory clinical patterns, thereby complicating diagnostic issues.

Thalamic aphasia can present as lexical semantic deficits with verbal paraphasia but with intact repetition and naming.[9] Characteristically this pattern of aphasia following thalamic strokes shows speedy recovery.[10]

After a thalamic stroke, a rare condition called Dejerine-Roussy syndrome or thalamic pain syndrome may occur; this usually presents initially with the absence of sensation and tingling of the body contralateral to the affected thalamus. Months later, numbness occurs, eventually developing to severe chronic pain.[11] It is due to the involvement of the thalamogeniculate branch, thereby leading to excruciating pain owing to the absence of central cortical inhibition.[12]

The reticular thalamic nucleus, a pacemaker zone for rhythmic cortical activity, may be the ictus for generalized spike-wave as seen in idiopathic generalized epilepsy.[13]

Patients with alcoholic Korsakoff syndrome have damage to their mamillary bodies, which can extend into the thalamus via the mammillothalamic fasciculus.[14][15]

A hereditary prion disease called fatal familial insomnia exists in which the gene PRNP located on chromosome 20 at p13 deposits in the thalamus, causing degeneration over time. Patients develop worsening insomnia that can have associated psychiatric symptoms such as panic attacks, paranoia, and phobias. They then develop hallucinations and the complete inability to sleep. Rapid weight loss follows with dementia and mutism until death occurs.[16][17]

The “pulvinar sign” is an MRI identification technique originally developed as a non-invasive method to identify patients with Creutzfeldt-Jakob disease.[18] Essentially, this technique looks for posterior thalamus changes on magnetic resonance imaging that appear as density changes in the shape of hockey sticks. Fabry disease is an X-linked lysosomal storage disease in which a deficiency of the enzyme alpha-galactosidase A causes an acclamation of globotriaosylceramide in the blood which deposits into tissues and organs. The pulvinar sign has been found to be a highly specific sign of Fabry disease of patients with cardiac and kidney involvement.[19]

With regards to anatomical changes, the interthalamic adhesions appear enlarged in patients with Arnold-Chiari malformation type II.[20] Additionally, the ventral intermediate nucleus of the thalamus has been the target for deep brain stimulation for the treatment of medically refractory essential tremors and tremor-dominant Parkinson disease with some success.[5]

Other Issues

'Eye peering at the tip of the nose' has been taken as a consistent clinical sign in cases of thalamic hemorrhages.[21]


  • Image 11046 Not availableImage 11046 Not available
    Image courtesy S Bhimji MD
Attributed To: Image courtesy S Bhimji MD

Interested in Participating?

We are looking for contributors to author, edit, and peer review our vast library of review articles and multiple choice questions. In as little as 2-3 hours you can make a significant contribution to your specialty. In return for a small amount of your time, you will receive free access to all content and you will be published as an author or editor in eBooks, apps, online CME/CE activities, and an online Learning Management System for students, teachers, and program directors that allows access to review materials in over 500 specialties.

Improve Content - Become an Author or Editor

This is an academic project designed to provide inexpensive peer-reviewed Apps, eBooks, and very soon an online CME/CE system to help students identify weaknesses and improve knowledge. We would like you to consider being an author or editor. Please click here to learn more. Thank you for you for your interest, the StatPearls Publishing Editorial Team.

Neuroanatomy, Thalamus - Questions

Take a quiz of the questions on this article.

Take Quiz
An 8-year-old boy undergoes magnetic resonance imaging (MRI) due to unexplained severe headaches. MRI reveals a mass in the left medial thalamus. Compression of which structure is at risk as the mass continues to expand medially?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
A 3-year-old girl climbs to the top of a counter trying to find a snack. On the way across the counter, her hand touches a hot stove. Which nucleus of the thalamus relays this sensory information to her cerebral cortex?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
A 65-year-old female has been treated for hypertension for 6 years. While working in the kitchen, she suddenly falls to the floor and remains unconscious for 2 hours. She is diagnosed as having had a cerebrovascular accident. The patient is found to have impairment of sensation of the entire left side of her body. Minor pinprick stimulation on the left elicits marked emotional reactions. The patient describes the sensation as "having a red-hot poker jabbed into my skin." What is the most likely cause of her signs and symptoms?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
A 76-year-old male was brought to the emergency department after police found him in the streets surrounded by beer cans with altered mental status. The patient is unoriented to person, place, date, and situation. He cannot recall memories of his past when prompted. He attempts to respond to your questioning but his speech is either incomprehensible or out of context. There is a concern that his ability to form memories may be impaired. You recall that the thalamus is part of the limbic system and has a role in processing memories. The thalamus of this patient may have acquired injury due to severe damage to which of the following structures?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
Scientists working on lab rats are interested in further researching the development of the thalamus. They would like to look for molecular markers as early in development as possible. Which derivative of the neural tube should they look for molecular markers on?

(Move Mouse on Image to Enlarge)
  • Image 2217 Not availableImage 2217 Not available
    Contributed by Gray's Anatomy Plates
Attributed To: Contributed by Gray's Anatomy Plates



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up

Neuroanatomy, Thalamus - References

References

Savage LM,Sweet AJ,Castillo R,Langlais PJ, The effects of lesions to thalamic lateral internal medullary lamina and posterior nuclei on learning, memory and habituation in the rat. Behavioural brain research. 1997 Jan;     [PubMed]
Stein T,Moritz C,Quigley M,Cordes D,Haughton V,Meyerand E, Functional connectivity in the thalamus and hippocampus studied with functional MR imaging. AJNR. American journal of neuroradiology. 2000 Sep;     [PubMed]
Child ND,Benarroch EE, Anterior nucleus of the thalamus: functional organization and clinical implications. Neurology. 2013 Nov 19;     [PubMed]
Steriade M,Llinás RR, The functional states of the thalamus and the associated neuronal interplay. Physiological reviews. 1988 Jul;     [PubMed]
Banerjee S,Shinde R,Sevick-Muraca EM, Probing Static Structure of Colloid-Polymer Suspensions with Multiply Scattered Light. Journal of colloid and interface science. 1999 Jan 1;     [PubMed]
Scholpp S,Lumsden A, Building a bridal chamber: development of the thalamus. Trends in neurosciences. 2010 Aug;     [PubMed]
Cinalli G,Aguirre DT,Mirone G,Ruggiero C,Cascone D,Quaglietta L,Aliberti F,Santi SD,Buonocore MC,Nastro A,Spennato P, Surgical treatment of thalamic tumors in children. Journal of neurosurgery. Pediatrics. 2018 Mar;     [PubMed]
Ramachandran VS,McGeoch PD,Williams L, Can vestibular caloric stimulation be used to treat Dejerine-Roussy Syndrome? Medical hypotheses. 2007;     [PubMed]
Kopelman MD,Thomson AD,Guerrini I,Marshall EJ, The Korsakoff syndrome: clinical aspects, psychology and treatment. Alcohol and alcoholism (Oxford, Oxfordshire). 2009 Mar-Apr;     [PubMed]
Rahme R,Moussa R,Awada A,Ibrahim I,Ali Y,Maarrawi J,Rizk T,Nohra G,Okais N,Samaha E, Acute Korsakoff-like amnestic syndrome resulting from left thalamic infarction following a right hippocampal hemorrhage. AJNR. American journal of neuroradiology. 2007 Apr;     [PubMed]
Schenkein J,Montagna P, Self-management of fatal familial insomnia. Part 2: case report. MedGenMed : Medscape general medicine. 2006 Sep 14;     [PubMed]
Jansen C,Parchi P,Jelles B,Gouw AA,Beunders G,van Spaendonk RM,van de Kamp JM,Lemstra AW,Capellari S,Rozemuller AJ, The first case of fatal familial insomnia (FFI) in the Netherlands: a patient from Egyptian descent with concurrent four repeat tau deposits. Neuropathology and applied neurobiology. 2011 Aug;     [PubMed]
Zeidler M,Sellar RJ,Collie DA,Knight R,Stewart G,Macleod MA,Ironside JW,Cousens S,Colchester AC,Hadley DM,Will RG, The pulvinar sign on magnetic resonance imaging in variant Creutzfeldt-Jakob disease. Lancet (London, England). 2000 Apr 22;     [PubMed]
Burlina AP,Manara R,Caillaud C,Laissy JP,Severino M,Klein I,Burlina A,Lidove O, The pulvinar sign: frequency and clinical correlations in Fabry disease. Journal of neurology. 2008 May;     [PubMed]
Wolpert SM,Anderson M,Scott RM,Kwan ES,Runge VM, Chiari II malformation: MR imaging evaluation. AJR. American journal of roentgenology. 1987 Nov;     [PubMed]
Schmahmann JD, Vascular syndromes of the thalamus. Stroke. 2003 Sep;     [PubMed]
Wilkins RH,Brody IA, The thalamic syndrome. Archives of neurology. 1969 May;     [PubMed]
Afzal U,Farooq MU, Teaching neuroimages: thalamic aphasia syndrome. Neurology. 2013 Dec 3;     [PubMed]
Ozeren A,Sarica Y,Efe R, Thalamic aphasia syndrome. Acta neurologica Belgica. 1994;     [PubMed]
Kelemen A,Barsi P,Gyorsok Z,Sarac J,Szucs A,Halász P, Thalamic lesion and epilepsy with generalized seizures, ESES and spike-wave paroxysms--report of three cases. Seizure. 2006 Sep;     [PubMed]
Choi KD,Jung DS,Kim JS, Specificity of     [PubMed]

Disclaimer

The intent of StatPearls is to provide practice questions and explanations to assist you in identifying and resolving knowledge deficits. These questions and explanations are not intended to be a source of the knowledge base of all of medicine, nor is it intended to be a board or certification review of Neurology-Epilepsy. The authors or editors do not warrant the information is complete or accurate. The reader is encouraged to verify each answer and explanation in several references. All drug indications and dosages should be verified before administration.

StatPearls offers the most comprehensive database of free multiple-choice questions with explanations and short review chapters ever developed. This system helps physicians, medical students, dentists, nurses, pharmacists, and allied health professionals identify education deficits and learn new concepts. StatPearls is not a board or certification review system for Neurology-Epilepsy, it is a learning system that you can use to help improve your knowledge base of medicine for life-long learning. StatPearls will help you identify your weaknesses so that when you are ready to study for a board or certification exam in Neurology-Epilepsy, you will already be prepared.

Our content is updated continuously through a multi-step peer review process that will help you be prepared and review for a thorough knowledge of Neurology-Epilepsy. When it is time for the Neurology-Epilepsy board and certification exam, you will already be ready. Besides online study quizzes, we also publish our peer-reviewed content in eBooks and mobile Apps. We also offer inexpensive CME/CE, so our content can be used to attain education credits while you study Neurology-Epilepsy.