Table 2.

Pathophysiological mechanisms relevant to iNPH induced by apneas during sleep

• Recurrent hypoxemia (low PaO2) hypercapnia (elevated PaCO2) and respiratory acidosis (low blood pH) • Activation of carotid and aortic chemoreceptors

• Stimulation of rostral pontine respiratory neurons

• Firing of solitary tract nucleus neurons, dorsal medullary respiratory group, and ventral group nucleus ambiguus • Repeated reflex contractions of respiratory chest and abdominal muscles

• Thoracoabdominal excursions greatly increase negative intrathoracic pressure

• Superior vena cava and intracranial venous hypertension in the dural sinuses

Decreased CSF absorption through Pacchionian granulations (arachnoid villae)

Tachycardia from atrial Bainbridge reflex

• Sympathetic (adrenergic) outburst

Arterial hypertension

Baroreceptor reflex activation

Peripheral vasoconstriction

Hyperglycemia

Hypercoagulability

• Inflammation from recirculation of hypoxic-acidotic blood

C-reactive protein (CRP)

Nuclear factor-κΒ (NF-κΒ)

Hyperhomocysteinemia

Interleukin-6 (IL-6)

Tumor necrosis factor alpha (TNF-α)