A 75-year-old man is brought to the emergency department after he was found unresponsive at home. The patient has a history of poorly controlled hypertension. Blood pressure is 240/120 mm Hg and pulse is 104 /min. He has extensor posturing and pinpoint pupils. CT scan of the head without contrast reveals an acute pontine hemorrhage with associated mass effect. The patient dies several hours later. Autopsy reveals disruption of all pigmented neurons in the posterior rostral pons at the lateral floor of the fourth ventricle. These neurons normally produce which of the following?

Question

A 75-year-old man is brought to the emergency department after he was found unresponsive at home.  The patient has a history of poorly controlled hypertension.  Blood pressure is 240/120 mm Hg and pulse is 104 /min.  He has extensor posturing and pinpoint pupils.  CT scan of the head without contrast reveals an acute pontine hemorrhage with associated mass effect.  The patient dies several hours later.  Autopsy reveals disruption of all pigmented neurons in the posterior rostral pons at the lateral floor of the fourth ventricle.  These neurons normally produce which of the following?

Quizplus · Accepted Answer

This patient had a hypertensive hemorrhage in the pons at the level of the locus ceruleus, a paired pigmented brainstem nucleus located in the posterior rostral pons near the lateral floor of the fourth ventricle. The locus ceruleus functions as the principal site for norepinephrine synthesis in the brain and projects to virtually all parts of the central nervous system. It is involved in the control of mood, arousal (reticular activating system), sleep-wake states, cognition, and autonomic function (eg, blood pressure control). Abnormal activation of the locus ceruleus has been implicated in the pathogenesis of anxiety disorders (eg, panic attacks). Patients with bilateral pontine hemorrhage typically present with coma due to disruption of the reticular activating system. Other features usually include total paralysis with extensor posturing due to corticospinal and corticobulbar tract injury and pinpoint pupils secondary to descending sympathetic tract damage. (Choice A) Dopamine is produced in the ventral tegmental area and substantia nigra pars compacta located in the midbrain. The major dopaminergic pathways in the brain include the mesolimbic and mesocortical pathways (regulate cognition and behavior), the nigrostriatal pathway (regulates coordination of voluntary movements), and the tuberoinfundibular pathway (inhibits prolactin secretion). (Choice B) Dynorphin is an opioid peptide that modulates the pain response. It is produced mostly in the periaqueductal gray, rostral ventral medulla, and dorsal horn of the spinal cord. (Choice C) Norepinephrine is converted to epinephrine primarily in the adrenal medullae. Both of these neurotransmitters are released by the adrenal glands into the circulation after stimulation by sympathetic cholinergic preganglionic neurons. (Choices D and F) Histamine and orexin are produced in the posterior hypothalamus and play an important role in arousal and wakefulness. (Choices G and H) Oxytocin and vasopressin (antidiuretic hormone) are hormones produced by the hypothalamus and released from the posterior pituitary. Oxytocin promotes milk letdown and uterine contractions, whereas vasopressin causes vasoconstriction and free water reabsorption in the renal collecting ducts. Educational objective: The locus ceruleus is a paired brainstem nucleus located in the posterior rostral pons near the lateral floor of the fourth ventricle and functions as the principal site for norepinephrine synthesis in the brain. It projects to virtually all parts of the central nervous system and helps control mood, arousal (reticular activating system), sleep-wake states, cognition, and autonomic function. __________ References: Organization of the locus coeruleus-norepinephrine system. (http://www.ncbi.nlm.nih.gov/pubmed/26528750) Functional neuroanatomy of the noradrenergic locus coeruleus: its roles in the regulation of arousal and autonomic function part I: principles of functional organisation. (http://www.ncbi.nlm.nih.gov/pubmed/19506723)

A 75-Year-Old Man Is Brought to the Emergency Department After