Article, Surgery, Traumatology

Mimics of subacute subdural hematoma in the ED

Unlabelled imagesubdural hematoma in “>American Journal of Emergency Medicine 31 (2013) 634.e1-634.e3

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American Journal of Emergency Medicine

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Case Report

Mimics of Subacute subdural hematoma in the ED?


Diagnosing the true etiology of a subdural fluid collection is challenging in the acute setting of an emergency department (ED). In case of a subdural fluid collection at computed tomographic imaging, the possibility of a subdural hematoma will be considered at once. However, other causes such as Subdural empyema and dural metastases with pachymeningitis hemorrhagica must be kept in mind. Especially when there is a medical history of recent sinusitis or malignancy. We describe 3 patients who presented to the ED with a history of Progressive headache, aphasia, and a right-sided hemipar- esis in whom a isodense subdural fluid collection was demonstrated with computed tomographic imaging.

We describe three patients who presented to the emergency department (ED) with similar complaints; a history of progressive headache, aphasia and a right-sided hemiparesis. In each patient computed tomography (CT) of the head was performed, which in all cases showed an isodense subdural fluid collection. All three patients initially were presumed to have a subacute subdural hematoma. In 2 of these patients this Initial diagnosis proved to be wrong, indicating that clinical presentation and CT findings can resemble findings of a subacute subdural hematoma.

A 66-year-old woman presented at the ED with a history of progressive headache during the last four weeks, difficulty of speech and weakness of the right arm. Her past medical history included a right occipital cerebral infarction without residual defects, pulmonary embolism, breast carcinoma, and metastasized lung carcinoma, which was considered as a stable disease after recent treatment with chemotherapy. There was no history of recent head trauma. The patient did not use oral anticoagulants. On neurologic examination, she had a clear consciousness with expressive aphasia and mild paresis of the right arm. Laboratory findings showed no abnormalities. Coagulation tests were normal.

Unenhanced CT of the brain was performed (Fig. A), which showed a 10 mm iso- to hypodense crescent shaped extra-axial fluid collection that spread over the left convexity of the brain and compressed the left hemisphere The sulci were however not completely effaced. In addition a scar of a previous stroke was seen on the right occipital side. The diagnosis subacute subdural hematoma was made, and the patient was admitted to the neurology ward for neurological observation. As symptoms improved spontaneously she was treated conservatively and discharged after 6 days with slight residual symptoms. In the outpatient clinic a control CT was performed three weeks later, which showed an unchanged subdural collection with lytic abnormalities in the skull (Fig. F). In retrospect, these lytic bone

? Conflict of Interest: None.

lesions were already visible seen on the initial CT. Gadolinium enhancED magnetic resonance imaging (MRI) was performed (Fig. D) showing thickening of the meninges close to the lytic bone lesion on the left side, with pathological Contrast enhancement of the subdural mass. Moreover, 3 intracerebral lesions were seen, suspect for metastases. Diagnosis of pachymeningitis hemorrhagica interna as a result of dural metastases was made. Patient was treated with whole- brain radiotherapy and died 3 months later.

A previous healthy 31-year-old man was brought to the ED in a confusional state. He had complaints of nasal congestion and a progressive headache during the last four days. His family mentioned a history of alcohol and substance abuse. There had been no history of a head trauma, nor did he use oral anticoagulants. Upon neurologic examination he had a decreased level of consciousness; opening eyes to verbal stimuli, best motor response was localizing pain with the left arm, verbal response showed aphasia. There was a mild paresis of the right arm. Additional physical examination revealed slight meningismus and a temperature of 37.3 degrees Celsius. Laboratory findings showed an elevated C-Reactive Protein level of 308 mg/l (normal b 1 mg/L) and a white blood cell count of 14.5 x 109/L (normal 4-10 x 109/L). Unenhanced CT of the brain (Fig. B) showed an isodense extra-axial collection of fluid over the left hemisphere and ventricle with a thickness of 10 mm, suggesting a subacute subdural hematoma. On contrast-enhanced CT of the brain (Fig. E), linear enhancement of the medial surface was visible. The patient was admitted to the neurology ward. Two hours later he deteriorated to a comatose state with a right-sided hemiplegia, persistent vomiting and rising temperature (N 39?C). T1-weighted MRI showed an extra- axial, hyperintense fluid collection over the left cerebral hemisphere, with restricted diffusion on diffusion-weighted imaging (DWI). T1- weighted gadolinium enhanced imaging showed four rim enhanced pockets surrounded by vasogenic edema, suggesting subdural empyema. Also fluid levels were noted in both maxillary and frontal sinuses, which were also present on the initial CT. An emergency left- parietal craniotomy was performed and purulent fluid evacuated. Intravenous Penicillin was started and continued for 6 weeks. A ?– hemolytic streptococcus was cultured from the empyema, most likely originating from paranasal sinusitis. The patient was discharged without symptoms a couple of days after admission. No specific intervention for the sinusitis was performed.

A 58-year-old man presented to the ED with a progressive

headache, speech difficulties and gait disturbances since three days. Two weeks previous he had suffered a blunt trauma by bumping his head against a door without loss of consciousness. The past medical history consisted of diabetes and a myocardial infarction for which he used antiplatelet medication. On Neurological examination there was a normal level of consciousness, a mild expressive aphasia and a slight paresis of the right leg. There was no thrombocytopenia. Unenhanced CT of the brain (Fig. C) showed

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634.e2 Case Report / American Journal of Emergency Medicine 31 (2013) 634.e1634.e3

Fig. A, Patient A. Unenhanced CT indicating subdural fluid collection over the left convexity (arrow). B, Patient B. Unenhanced CT indicating subdural fluid collection over the left convexity (arrow). C. Patient C, Unenhanced CT indicating subdural fluid collection over the left convexity (arrow). D, MRI T2 with gadolinium of Patient A. E, Contrast enhanced CT of patient B. F, CT bone setting of patient A. Lateral orbital wall shows interruption of bone structure (arrow).

a left-sided isodense fluid collection with mass effect on the left hemisphere and shift of midline structures to the right to subacute subdural hematoma over the left hemisphere was diagnosed. A left-parietal burr hole was performed to evacuate the subdural hematoma. The patient was discharged two days later without residual symptoms. Four weeks later a CT of the brain showed a small residual left sided subdural hematoma.

All three patients presented with comparable complaints and neurological symptoms. In all three cases CT imaging initially suggested a subdural hematoma. However, in 2 of these patients, another diagnosis was made eventually. Patient A was diagnosed with pachymeningitis hemorrhagica interna as a result of dural metastases and patient B had a subdural empyema following paranasal sinusitis. We describe these two alternative etiologies and discuss clinical symptoms as well as imaging signs that should prompt an alternative etiology.

Pachymeningitis hemorrhagica interna can be found as a result of dural metastases [1-4]. In this condition a subdural hematoma arises from the carcinomatous invasion of the meninges. This occurs in 15- 40% of patients with dural metastases [2,5]. Neurological symptoms in pachymeningitis hemorrhagica interna mimic that of a subdural hematoma. Sometimes, skull tenderness may suggest dural metasta- sis with pachymeningitis hemorrhagica interna. Several theories have been formulated to explain the pathogenesis of subdural hematomas in dural metastases. First, the hemorrhage could be due to the rupture of fragile tumor neo-vessels. Second, dilatation or rupture of the capillaries of the inner dural layer may result from mechanical obstruction of the external dural vessels by the expanding skull metastases .Third, conversely chronic subdural hematoma could be the mediator rather than the consequence of subdural invasion, because the bleeding may alter the barrier properties of the dura mater and facilitate tumor infiltration in the dura. [2,3,5-9] Pachy-

meningitis hemorrhagica interna should not to be confused with spontaneous non-traumatic subdural hematomas, emerging from coagulation disorders caused by a malignancy [2-5]. Dural metastases are associated with different types of carcinomas, of which prostate cancer is the most frequent type of malignancy. It has also been described in breast, lung, stomach and hematologic malignancies. Occasionally, the primary tumor remains unknown, despite substan- tial investigation [2].

Unenhanced CT-imaging can detect bone involvement in case of metastases which should raise suspicion of dural metastasis as the cause of a found subdural fluid collection. Studies of choice are contrast-enhanced CT or Gadolinium enhanced MRI . Both tech- niques can accurately depict dural metastases as enhancing dural masses extending along the bone structures [1,2]. Dural metastases present as a thickening of the dura mater, which may be widespread along the dura. Sometimes a nodular pattern is found resembling a meningeoma. In contrast to subacute of chronic subdural hemato- mas, the lack of blood-brain barrier accounts for the intense and homogenous contrast enhancement [1,2]. Commonly Gadolinium enhanced MR findings in subdural hematomas include an enhancing and thickened dura, sometimes with enhancing membranes. DWI imaging shows a hypointense subdural fluid collection. Hyperintense foci suggest solid clots and a hyperintense subdural band indicates relatively fresh bleeding from the outer membrane. On CT imaging with contrast medium, the enhancing dura and membranes combination with inward displacement of the cortical vessels will be visible.

The presenting symptoms of subdural empyema are due to increased intracranial pressure, meningeal irritation or co-existing cerebritis [10]. The most common symptoms are headache, fever and neck stiffness. Neurological deterioration can proceed rapidly causing a decreased level of consciousness and focal neurologic deficits. Rapid

Case Report / American Journal of Emergency Medicine 31 (2013) 634.e1634.e3

progression of symptoms is a hallmark of subdural empyema [10].


Marlijn H. de Beer MD

Seizures occur frequently in subdural empyema, but are uncommon in subdural hematoma [10]. Fever is a common symptom and laboratory findings almost universally show an elevated erythrocyte sedimen- tation rate and leukocytosis, with a predominance of polymorphonu- clear cells [10-14]. Most cases of subdural empyema occur in the second decade of life in patients who are otherwise healthy. Moreover, there is a marked predisposition in males [10-12]. Subdural empyema evolves from a paranasal sinusitis in the majority of cases, in which there is direct extension from the infected sinus due to osteomyelitis or hematogenic spread due to retrograde thrombo- phlebitis spreading from externally to the intracranial space [10-12]. Other causes include meningitis, Otitis media, postsurgical complica- tions, dental infections, previous head trauma or bacteremic seeding of a previous subdural hematoma [10-13]. The causative microorgan- ism is Streptococcus Milleri in the majority of cases, but other Streptococcus or Enterococcus species have also been reported. Frequently, three or more microorganisms are cultured from the empyema [10,11,14]. Subdural empyema is a neurosurgical emer- gency and immediate decompressive craniotomy can be lifesaving [10,11,13].

On CT-imaging there are several findings suggesting empyema,

such as a hypodense subdural lesion with medial linear membrane enhancement [11]. Sometimes these empyemas occur bilaterally. Grey matter/white matter differentiation can be decreased, indicating the presence of oedema [10,11,15]. The fronto-ethmoid and maxillary sinuses may be opacified suggesting sinusitis. In cases of mastoiditis the mastoid bone can appear sclerosed [11,15]. On contrast enhanced CT imaging strong peripheral rim enhancement can be seen [11,12,15]. DWI MRI can be useful in distinguishing subdural empyema from other subdural fluid collections, like benign subdural effusions [10,16,17]. In contrast to subdural empyemas, these benign effusions appear to have a low signal on DWI imaging, identical to CSF [10,17,18].

Both the clinical picture as well as the imaging findings of subdural empyema and pachymeningitis hemorrhagica interna can mimic those of a simple subdural hematoma. As the course of these diseases can be different, and also therapy differs, it is important to make the correct diagnosis as soon as possible because of the high morbidity and mortality. Fever, meningismus and elevated infectious parame- ters are suggestive of subdural empyema. In addition a history of paranasal sinusitis or dental disease or opacified sinuses should prompt the diagnosis of empyema instead of a simple hematoma. A subdural fluid collection in a patient with a history of malignancy should raise suspicion of dural metastases as the cause of the bleeding. Thickening of the dura on unenhanced CT-imaging is suggestive of dural metastasis [2]. In case of any doubt one should perform a contrast-enhanced CT-scanning or preferably Gadolinium-enhanced MR-imaging.

Department of Neurology, Hagaziekenhuis

The Hague, The Netherlands E-mail address: [email protected]

Ad P. van Gils MD, PhD

Department of Radiology, Hagaziekenhuis

The Hague, The Netherlands

Hille Koppen MD

Department of Neurology, Hagaziekenhuis

The Hague, The Netherlands


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