Medical Image of the Week: Empyema Necessitans

Figure 1. Panel A: chest radiograph on admission showed mass like lesion centered at the right upper lobe. Panel B: Coronal CT cut showing loculated fluid collection demonstrating peripheral rim enhancement. There is extension of pleural fluid into the soft tissues of the adjacent right chest wall (white arrow).

Figure 2. Panel A: chest radiograph after VATS decortication and antibiotic course shows resolution. Panel B: axial CT cut after completion of therapy shows complete resolution.

A previously healthy 46-year-woman was evaluated for two week history of right shoulder pain, associated pleuritic chest pain and dyspnea.

Chest radiograph showed right apical mass (Figure 1A). Imaging  showed loculated fluid collection with extension into the soft tissues of the adjacent right chest wall suggestive of empyema necessitans (Figure 1B).

Chest Tube placement was done along with broad spectrum antibiotics. Blood and pleural fluid cultures showed methicillin-resistant Staphylococcus aureus (MRSA). Due to persistence of loculation despite antibiotics, she underwent a video-assisted-thoracoscopic surgery (VATS) for decortication and further drainage of the effusion.

Symptoms and radiologic findings improved and she was discharged with intravenous antibiotics to complete a six week course. Chest imaging at six week period showed complete resolution (Figure 2).

Empyema necessitans, defined by the extension of an empyema through the parietal pleura, into surrounding tissue is becoming rare with the routine drainage of empyema and antibiotics use. Common causative pathogens include Mycobacterium tuberculosis, Actinomyces israelii, Streptococcus pneumoniae, and Staphylococcus aureus (1). Surgical treatments for thoracic empyema include chest tube drainage, debridement via VATS, decortication, open window thoracostomy, and thoracoplasty (2).

Kai Rou Tey MD¹, Bhupinder Natt MD²

¹Department of Internal Medicine - South Campus and ²Department of Pulmonary, Critical Care, Allergy and Sleep

University of Arizona College of Medicine

Tucson, AZ USA

References

1. Kono SA, Nauser TD. Contemporary empyema necessitatis. Am J Med. 2007;120(4):303-5. [CrossRef] [PubMed]
2. Molnar TF. Current surgical treatment of thoracic empyema in adults. Eur J Cardiothorac Surg. 2007;32(3):422-30. [CrossRef] [PubMed] 

Cite as: Tey KR, Natt B. Medical image of the week: empyema necessitans. Southwest J Pulm Crit Care. 2015;11(6):271-2. doi: http://dx.doi.org/10.13175/swjpcc139-15 PDF 

Medical Image of the Week: Diffuse Axonal Injury

Figure 1. Panel A: Non-contrast CT of the head demonstrating hyperdense foci at the gray-white junction of the cortex and subcortical white matter (red arrows). Panel B: Hyperdense focus in the pons (red arrow).

Figure 2. MRI of the brain with a gradient recall echo (GRE) sequence demonstrating more pronounced hypointense foci consistent with hemorrhage.

An 18-year-old man without any significant past medical history presented to the emergency room trauma bay as an unrestrained passenger involved in a head-on collision at 85 mph. In the emergency room, he was found to have a GCS of 6 and was intubated for airway protection. A non-contrast CT of the head demonstrated hyperdense foci in the frontal lobes at the gray-white junction (Figure 1A) and a hyperdense focus in the pons (Figure 1B) consistent with punctate hemorrhages. An MRI of the brain with a gradient recall echo (GRE) sequence (Figure 2) demonstrated more pronounced hypointense foci consisent with hemorrhage. In the setting of the patient’s deceleration injury, the summation of his clinical and imaging findings was consistent with diffuse axonal injury.

Diffuse axonal injury (DAI) is pattern of closed head injury that results in a traumatic shear injury to the neuronal axons secondary to sudden deceleration and change in angular momentum. This pattern of injury often occurs at the interface between tissues of differing density such as the gray-white junction of the cerebral cortex and subcortical white matter. DAI can also be seen in deeper portions of the brain, such as the corpus callosum and brainstem, that are relatively fixed compared with more superficial portions of the brain resulting in greater rotational/ shear stress forces focused in these locations during sudden deceleration. Visible lesions on CT often underestimate the extent of neuronal injury (often described as the “tip of iceberg”), and neuronal injury is better delineated on MRI.

Most patients present with an immediate coma necessitating intubation for airway protection.  In mild cases, patients often experience mild traumatic brain injury characterized by heachaces, mild cognitive impairment, and personality changes. In more severe cases, DAI can result in a persistent vegetative state. Treatment is supportive in all cases.

Jack Hannallah, MD¹; Tammer Elaini, MD²; Kelly Wickstrom, DO³; Rorak Hooten, MD³; Michael Habib, MD²

Departments of ¹Surgery,²Pulmonary/Critical Care, and ³Internal Medicine

University of Arizona

Tucson, AZ USA

References

1. Yanagawa Y, Sakamoto T, Takasu A, Okada Y. Relationship between maximum intracranial pressure and traumatic lesions detected by T2*-weighted imaging in diffuse axonal injury. J Trauma. 2009;66(1):162-5. [CrossRef] [PubMed] 
2. Tong KA, Ashwal S, Holshouser BA, Shutter LA, Herigault G, Haacke EM, Kido DK. Hemorrhagic shearing lesions in children and adolescents with posttraumatic diffuse axonal injury: improved detection and initial results. Radiology. 2003;227(2):332-9. [CrossRef] [PubMed] 

Cite as: Hannallah J, Elaini T, Wickstrom K, Hooten R, Habib M. Medical image of the week: diffuse axonal injury. Southwest J Pulm Crit Care. 2015;11(6):264-5. doi: http://dx.doi.org/10.13175/swjpcc121-15 PDF