CAUDAL RETICULAR FORMATION

The reticular formation is an aggregation of several subtypes of interconnected neurons extending through out the brainstem tegmentum.

It is the central core of nuclei that runs through the brainstem.

The caudal RF of the pons and medulla works together with the cranial nerve nuclei and the spinal cord to carry out a variety of motor, reflex and autonomic functions.

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The lateral third of the reticular formation contains small-sized cells (called parvocellular regions)

The medial two thirds of the reticular formation contains different groups of large-sized cells (called magnocellular regions)

Additional groups of cells, called the raphe nuclei, lie along or adjacent to the midline of the upper medulla, pons, and midbrain, are also included in the reticular formation.

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Motor Systems:

o The cerebellum and RF have reciprocal connections. Cerebellar fibbers projecting to the RF arise from the fastigial nucleus.

oCorticoreticular fibres arise from the cerebral cortex that terminate in areas where the reticulospinal tracts arise

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o The pontine RF has efferent connections to cranial nerves 3 and 6 via the PPRF.

Autonomic Connections:

o Cranial nerves 9 and 10 have projections to the medullary RF via the solitary nucleus.

o Lateral and medial regions of the hypothalamus have connections to the pontine reticular formation

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AAA Alertness Attention Awareness

Autonomic

Caudal RF Functions

Reflex

Sensory Motor

Modulate muscle tone of

"antigravity muscles

Regulate posture

Participate in

automatic

reflex

mechanisms.

(Extensors)

Patella Reflex

Integrates signals from FEF + vestibular nuclei

Enables conjugate eye movements in response to changes in body posture & head position in space

Corneal Reflex

Key structure:

RVM

Modulates

inhibition

of pain

Control of Respiratory rhythm

Control of HR & BP

Maintaining sphincter control

Feeding reflexes: chewing, sucking, salivating, swallowing, and licking

Respiratory reflexes: phonation, sneezing coughing, sighing, vomiting, hiccupping

Pseudobulbar laughter and crying

1. Typically one sees apneustic breathing with involvement of the caudal reticular formation. [1]

2. What is apneustic breathing?

3. Generally has a very poor prognosis [2]

4. Ondines curse[2]- seen with lateral medullary syndrome [3], multiple sclerosis [4], infection [2], stroke [5]

5. Check for the pattern of breathing.

1. Responsible for autonomic control of oxygenated blood supply to various parts of the body under different conditions viz. high altitude, stress, etc [1]

2. Responsible for normal sinus rhythm [1]

3. Typically individuals will have loss of consciousness with change in position, or arrhythmias [6]

4. Vasomotor center- responsible for regulating blood pressure and homeostatic processes.[1]

5. Check for murmurs, irregular heartbeats, discrepancy in the carotid and sinus rhythm.

1. Insomnia [1]

2. Gastrointestinal problems [8]

3. Phonation[3]

4. Persistent hiccups [7]

DIFFERENTIAL DIAGNOSES

Medical Physiology Updated Second Edition,Boron, Walter F., MD, PhD,Copyright 2012 by Saunders, an imprint of

Elsevier Inc.

Rostral Reticular Formation

Caudal Reticular Formation

Altered level of consciousness

Cardiovascular and respiratory dysfunction

Sleep disturbances

Abnormalities in the reflexive behaviors

Eg. hiccups

Altered attention

Muscle tone and postural abnormalities.

DIFFERENTIAL DIAGNOSES

Traurig, H. H. (n.d.). The Brain Stem Reticular Formation. Neuroscience, 273286. Blumenfeld, H: Neuroanatomy through Clinical Cases, Sunderland, Massachusetts: Sinauer Associates, Inc., MA, 2010.

Robbins, a, Schwartz-Giblin, S., & Pfaff, D. W. (1990). Ascending and descending projections to medullary reticular formation sites which activate deep lumbar back muscles in the rat. Experimental Brain Research. Experimentelle Hirnforschung. Experimentation Cerebrale, 80(3), 463474. doi:10.1007/BF00227988

Medullary Reticular Formation

Pontine Reticular Formation

Sudden sign of central apnea

Disorders of Gaze

Increased Blood pressure and cardiovascular dysfunction

Loss of sphincter control

Intractable hiccups

Sleep apnea (Ondines curse)

Loss of acoustic startle reflex, muscle tone abnormalities. Traurig, H. H. (n.d.). The Brain Stem Reticular Formation. Neuroscience, 273286. Blumenfeld, H: Neuroanatomy through Clinical Cases, Sunderland, Massachusetts: Sinauer Associates, Inc., MA, 2010

The reticular formation is a central core of nuclei that run through the entire length of the brainstem.

The rostral and caudal extensions highlight the two main functions of the reticular formation.

The caudal reticular formation of the pons and medulla work together with the cranial nuclei and the spinal cord to carry out a variety of important motor, reflex and autonomic functions.

There are no sophisticated tests or measures, which will isolate the involvement of the Caudal reticular formation.

The associated signs and symptoms will be a part of bigger cluster

Observation is the key!

1. The Human Brain: An Introduction to its Functional Anatomy 5th ed by J Nolte chpt 11 pp. 262290

2. Giangaspero, F., Schiavina, M., Sturani, C., Mondini, S., & Cirignotta, F. (1987). Failure of automatic control of ventilation (Ondine's curse) associated with viral encephalitis of the brainstem: a clinicopathologic study of one case.Clinical neuropathology, 7(5), 234-237.

3. Terao, S. I., Miura, N., Osano, Y., Noda, A., & Sobue, G. (2004). Rapidly progressive fatal respiratory failure (Ondines curse) in the lateral medullary syndrome. Journal of Stroke and Cerebrovascular Diseases, 13(1), 41-44.

4. Auer, R. N., Rowlands, C. G., Perry, S. F., & Remmers, J. E. (1995). Multiple sclerosis with medullary plaques and fatal sleep apnea (Ondine's curse).Clinical neuropathology, 15(2), 101-105.

5.Bogousslavsky J, Caplan L. Stroke Syndromes. Cambridge: Cambridge University Press; 2001.

6.Bangalore, K. (2014). Left ventricular diastolic dysfunction & Cardiovascular autonomic neuropathy in type 2 Diabetes mellitusa cross sectional clinical Study at kims hospital and research centre (Doctoral dissertation, Rajiv Gandhi University of Health Sciences).

7.Park, M. H., Kim, B. J., Koh, S. B., Park, M. K., Park, K. W., & Lee, D. H. (2005). Lesional location of lateral medullary infarction presenting hiccups (singultus). Journal of Neurology, Neurosurgery & Psychiatry, 76(1), 95-98.

8.Travagli, R. A., Hermann, G. E., Browning, K. N., & Rogers, R. C. (2006). Brainstem circuits regulating gastric function. Annual review of physiology, 68, 279.

9. Clinical Neuroanatomy. Journal of Laryngology Otology (Vol. 20). doi:10.1007/978-3-642-19134-3

10. Pfaff, D. W., Martin, E. M., & Faber, D. (2012). Origins of arousal: Roles for medullary reticular neurons. Trends in Neurosciences, 35(8), 468476. doi:10.1016/j.tins.2012.04.008

11. Robbins, a, Schwartz-Giblin, S., & Pfaff, D. W. (1990). Ascending and descending projections to medullary reticular formation sites which activate deep lumbar back muscles in the rat. Experimental Brain Research. Experimentelle Hirnforschung. Experimentation Cerebrale, 80(3), 463474. doi:10.1007/BF00227988

12. Traurig, H. H. (n.d.). The Brain Stem Reticular Formation. Neuroscience, 273286.

13. Medical Physiology Updated Second Edition,Boron, Walter F., MD, PhD, Copyright 2012 by Saunders, an imprint of Elsevier Inc.

14. Blumenfeld, H: Neuroanatomy through Clinical Cases, Sunderland, Massachusetts: Sinauer Associates, Inc., MA, 2010.

15. Randy W. Beck: Functional Neurology for Practitioners of Manual Therapy. Elsevier Health Sciences, 2008Siegel and Sapru: essential neuroscience, (2nd Ed), Philadelphia: Lippincott Williams & Wilkins, 2011