bubble_chart Overview

The hypothalamus is an important subcortical center of the autonomic nervous system, closely related to visceral activities, endocrine functions, metabolism, temperature regulation, as well as consciousness and sleep. Therefore, clinical manifestations of hypothalamic injury are often severe. Isolated hypothalamic injuries are rare and usually occur alongside severe cerebral contusions or brainstem injuries. Typically, hypothalamic injury results when a skull base fracture extends across the sella turcica or its vicinity. In cases of grade III blast injuries or contrecoup brain injuries causing violent anteroposterior sliding along the longitudinal axis of the brain base, the hypothalamus may also be injured, often involving the pituitary stalk and pituitary gland. Pathological findings of such injuries commonly include focal hemorrhage, edema, ischemia, softening, and neuronal necrosis, with occasional instances of pituitary stalk rupture or intrapituitary hemorrhage.

bubble_chart Clinical Manifestations

It is generally believed that the anterior region of the hypothalamus contains the parasympathetic center, while the posterior region houses the sympathetic center. These two centers mutually regulate each other under the control of the cerebral cortex. Therefore, when the hypothalamus is damaged, it is more likely to cause autonomic nervous system dysfunction.

Consciousness and sleep disorders: The posterolateral region of the hypothalamus and the midbrain tegmentum are part of the ascending reticular activating system, which is responsible for maintaining wakefulness. This system is crucial for managing wakefulness and sleep. Once damaged, patients may exhibit somnolence, where they can be awakened but quickly fall back asleep. In severe cases, they may become comatose.

Circulatory and respiratory disturbances: After hypothalamic injury, cardiovascular function can exhibit various changes, including fluctuations in blood pressure (either high or low) and heart rate (either fast or slow). However, hypotension and tachycardia are more commonly observed, with significant variability. If hypotension is accompanied by hypothermia, the prognosis is poor. Respiratory rhythm disturbances are related to damage to the respiratory control center in the posterior hypothalamus, often manifesting as slowed or even stopped breathing. Injury to the preoptic area can lead to acute central pulmonary edema.

Thermoregulation disorders: Central hyperthermia caused by hypothalamic injury often rises abruptly, reaching 41°C or even higher, but with dry skin and reduced sweating. Skin temperature distribution is uneven, with limbs cooler than the torso, and no signs of inflammation or toxicity. Antipyretics are ineffective. Sometimes hypothermia occurs, or hyperthermia transitions to hypothermia. If physical warming measures fail, the prognosis is extremely poor.

Water metabolism disorders: These are often caused by injury to the supraoptic and paraventricular nuclei of the hypothalamus or damage to the supraopticohypophyseal tract within the pituitary stalk, leading to insufficient antidiuretic hormone secretion and resulting in diabetes insipidus. Daily urine output can exceed 4000–10000 ml, with a low specific gravity below 1.005.

Glucose metabolism disorders: These often coexist with water metabolism disorders, presenting as persistent hyperglycemia and increased blood osmotic pressure, without ketones in the urine. Patients experience severe dehydration, hemoconcentration, shock, and a very high mortality rate, a condition known as "hyperosmolar hyperglycemic nonketotic unconsciousness."

Digestive system disorders: A neural tract runs from the anterior hypothalamus to the dorsal vagal nucleus of the medulla oblongata, specifically managing the autonomic nervous system of the upper digestive tract. Damage to any part of this tract can lead to upper digestive tract lesions. Therefore, severe brain trauma involving the hypothalamus can easily cause gastric and duodenal mucosal erosion, necrosis, ulcers, and bleeding. The cause may be related to vasoconstriction and ischemia of the upper digestive tract, excessive vagal excitation, or hypergastrinemia and hyperacidity. Additionally, such patients often experience intractable hiccups, vomiting, and abdominal distension and fullness.

bubble_chart Diagnosis

Hypothalamic injury is often associated with severe cerebral contusion and laceration, brainstem injury, or intracranial hypertension. The clinical manifestations are complex and often intertwined, making pure, typical cases rare. Generally, the presence of certain signs indicative of hypothalamic injury is sufficient to consider its involvement. In recent years, the diagnostic accuracy of hypothalamic injury has significantly improved through CT and MRI examinations. However, focal hemorrhages near the third ventricle are sometimes difficult to detect on CT images due to volume effects, making MRI the preferred method for evaluating the hypothalamus. Even small, scattered punctate hemorrhages can be visualized. In the acute phase, these appear as low signal intensity on T₂-weighted images and isointense on T₁-weighted images. During the subacute and chronic phases, the hemorrhagic lesions show clear hyperintensity on T₁-weighted images, facilitating easier identification.

bubble_chart Treatment Measures

The treatment of hypothalamic injury is essentially the same as that of primary brainstem injury. However, due to the frequent occurrence of neuroendocrine disorders and metabolic disturbances caused by hypothalamic injury, the treatment is more challenging and complex. Careful and meticulous treatment and nursing are required under close observation, intracranial pressure monitoring, blood generation and transformation testing, and water-electrolyte balance to have hope of overcoming the critical condition.

bubble_chart Differentiation

Diencephalic seizure: Also known as posterior hypothalamic seizure or diencephalic epilepsy, it is a paroxysmal condition characterized by flushing of the face and neck, sweating, palpitation, tearing, salivation, trembling, and gastrointestinal discomfort. Each episode lasts from several minutes to 1-2 hours, but without spasm, and occasionally with the urge to urinate.