Paroxysmal sympathetic hyperactivity syndrome caused by fat embolism syndrome

Abstract

Paroxysmal sympathetic hyperactivity represents an uncommon and potentially life-threatening complication of severe brain injuries, which are most commonly traumatic. This syndrome is a clinical diagnosis based on the recurrent occurrence of tachycardia, hypertension, diaphoresis, tachypnea, and occasionally high fever and dystonic postures. The episodes may be induced by stimulation or may occur spontaneously. Underdiagnosis is common, and delayed recognition may increase morbidity and long-term disability. Trigger avoidance and pharmacological therapy can be very successful in controlling this complication. Fat embolism syndrome is a rare but serious complication of long bone fractures. Neurologic signs, petechial hemorrhages and acute respiratory failure constitute the characteristic presenting triad. The term cerebral fat embolism is used when the neurological involvement predominates. The diagnosis is clinical, but specific neuroimaging findings can be supportive. The neurologic manifestations include different degrees of alteration of consciousness, focal deficits or seizures. Management is supportive, but good outcomes are possible even in cases with very severe presentation. We report two cases of paroxysmal sympathetic hyperactivity after cerebral fat embolism, which is a very uncommon association.

Fat Embolism Syndrome With Cerebral Involvement: An Underrecognized Complication of Long Bone Fractures

“…The theorized biologic mechanism is that corticosteroids stabilize the phospholipid bilayer comprising cell members, thereby limiting free fatty acid levels and inhibiting complement-mediated leukocyte aggregation [ 1 ]. Despite this, the use of steroids is controversial, and further examination of the same trial showed no difference in mortality compared to control patients receiving standard prevention and supportive treatment [ 1 , 3 , 6 , 11 ]. Still, based on this study, some clinicians utilize methylprednisolone 6-90 mg/kg as FES prophylaxis in patients with long bone fractures [ 1 ].…”

“…Neurologic symptoms are the most common and occur in 85% of cases [ 1 , 7 ]. CFE is a sequela of FES and is diagnosed when neurological involvement is either seen on imaging or is the main symptomatic manifestation of the disease [ 3 , 6 ]. The condition occurs when fat emboli are scattered into the cerebral microvasculature with disruption of the blood-brain barrier and subsequent cerebral ischemia [ 8 ].…”

“…Early imaging is also critical, as CFE is typically seen between 24 and 72 hours of fracture; one retrospective study reported an average presentation of 18.4 hours after the initial insult [ 4 , 9 ]. It is also worth noting that the findings on MRI represent ischemic occlusions of cerebral arterioles, which causes cytotoxic edema on DWI in the acute stage and vasogenic edema on T2-weighted sequences in the later stages [ 2 - 3 , 6 ]. Therefore, although CFE may be confounded by other neurological processes, such as stroke or anoxic brain injury, early MRI in patients with neurological symptoms following fracture in the absence of other causes can hasten the diagnosis and allow for appropriately targeted management.…”

“…Cerebral fat embolism (CFE) has been described in about 10% of FES cases based on clinical criteria, but the true incidence is also unclear due to an absence of definitive diagnostic testing [5]. When clinical criteria are combined with neuroimaging, the reported incidence of CFE from long bone injuries is 0.9%-2.2% [3][4][5][6].…”

Cerebral Fat Embolism: A Rare East African Conundrum

“…These symptoms are consistent with certain autopsy results that show hemorrhaging and inflammation near petechiae sites dispersed through white matter tracts, likely caused by fat globules obstructing brain microvasculature [ 12 - 14 ]. Furthermore, fat emboli may localize to central areas that control catecholamine release, thereby explaining the specific association between CFE, increased catecholamine blood levels, and paroxysmal sympathetic hyperactivity (PSH) [ 12 , 15 ]. PSH can be clinically observed and include features such as tachycardia, hypertension, tachypnea, irregular motor tone, and hyperthermia [ 11 ].…”