Neurological injury [non progressive or progressive] causing abnormal respiratory rates suggesting abnormal control of ventilation can affect memory, thought, speech, and locomotor activity due to multi-system effects.
Control of ventilation depends on a brainstem neuronal network that controls activity of the motor neurons innervating the respiratory muscles. This network includes the pontine respiratory group and the dorsal and ventral respiratory groups in the medulla. Neurologic disorders affecting these areas or the respiratory motor unit may lead to abnormal breathing.
The brainstem respiratory network contains neurons critical for respiratory rhythmogenesis; this network receives inputs from peripheral and central chemoreceptors sensitive to levels of carbon dioxide (PaCO2) and oxygen (PaO2) and from forebrain structures that control respiration as part of integrated behaviors such as speech or exercise. Manifestations associated with disorders of this network include sleep apnea and dysrhythmic breathing frequently associated with disturbances of cardiovagal and sympathetic vasomotor control. Common disorders associated with impaired cardiorespiratory control include brainstem stroke or compression, syringobulbia, Chiari malformation, high cervical spinal cord injuries, and multiple system atrophy. By far, neuromuscular disorders are the more common neurologic conditions leading to respiratory failure.
Respiratory dysfunction constitute an early and relatively major manifestation of several neurologic disorders and may be due to an abnormal breathing pattern generation due to involvement of the cardiorespiratory network or more frequently to respiratory muscle weakness. Abnormalities of Respiratory Control and the Respiratory Motor Unit Nogués, Martín A. MD*; Benarroch, Eduardo MD† The Neurologist: September 2008 – Volume 14 – Issue 5 – p 273-288
Depressed breathing rate at rest and/or excited breathing rate at rest are key to brain function and locomotor function because of the possible chronic and acute on chronic respiratory acid base effects affecting the balance of PO2/PC02/pH and effects on intracranial pressure in particular.
It would seem wise to to count breathing rate at rest and to check for accessory muscle use in any unmedicated acute encephalopathy, altered mental status, autobiographical memory loss, disorganized thinking, mental confusion, chronic delirium [all locomotor subtypes]. dementia, and chronic dysphoric mood and/or euphoric mood and mixed states, in order to rule out hypercapnic encephalopathy.
Abnormal mood, mental status and breathing rate will need to be further investigated with an arterial blood gas test and treatment to correct PC02 will need to be tried in order to return the patient to normal baseline mental status and mood.
The patient will need to be monitored for encephalopathy attacks in the future if the injury to the ventilatory system cannot be corrected.