Disorders of Consciousness
The anatomic substrate for a disorder in consciousness is dysfunction in the reticular formation and the ascending reticular activating system (ARAS) because activation of the cerebral cortex during arousal and…
Thalamic Anatomy and Pathology
In addition, there are several cell groups along the midline and embedded in the internal medullary lamina (the intralaminar nuclei). These nuclei send projections more diffusely in the cerebral cortex,…
Thalamic Anatomy and Pathology (Continued)
The thalamic perforating arteries may also hemorrhage. This often produces a thalamic syndrome similar to ischemic infarction. However, as the hemorrhage grows it may press downward on the midbrain, causing…
Pituitary Apoplexy
Patients with pituitary apoplexy present with severe headache of acute onset, which is typically considered as the worst headache ever experienced. Nausea and vomiting are very common. The rapid expansion…
Postpartum Pituitary Infarction (Sheehan Syndrome)
To understand the development of postpartum pituitary infarction, one has to consider that the pituitary gland becomes hyperplastic (approximately doubling in mass) during pregnancy as a result of progressive lactotroph…
Severe Anterior Pituitary Hormone Deficiencies (Panhypopituitarism)
Pituitary macroadenomas, which, by definition, exceed 10 mm in greatest diameter, may cause multiple anterior pituitary hormone deficiencies but only rarely cause diabetes insipidus preoperatively. In contrast, large suprasellar tumors…
Anterior Pituitary Hormone Deficiencies
A wide variety of conditions may cause dysfunction of the hypothalamus or pituitary, leading to selective or universal, partial or complete, acute or chronic loss of adenohypophyseal hormone secretion (anterior…
Anatomic Relationships of the Pituitary Gland
The optic chiasm rests superiorly to the diaphragma sellae. Nerve fibers originating in the nasal portion of each retina cross at the chiasm to the contralateral side and join ipsilateral…
Posterior Pituitary Gland
Oxytocin and antidiuretic hormone (vasopressin) are made by distinct populations of large (magnocellular) neurons in both the paraventricular (PVN) and supraoptic (SON) nuclei, which release the hormones from their axons…
