Stroke and Other PRES-sing Issues: A Photo Essay

Reversible Coma in a Young Postpartum Woman

A 22-year-old woman presented at 36 weeks of gestation with a 1-day history of mild headache, blurred vision, and epigastric pain. She was admitted for severe preeclampia with signs of early labor. Treatment with magnesium sulfate and IV labetolol was started. During labor, however, she experienced multiple generalized tonic clonic seizures. Despite a normal vaginal delivery, she remained postictal.

Neurologic exam was notable for withdrawal of all 4 extremities to painful stimuli. Pupils were mid-position fixed and deep tendon reflexes were 2+ with extensor plantar response bilaterally. She had decorticate posturing. IV levetiracetam was started, and she was transferred to the ICU. Brain CT without contrast showed marked diffuse vasogenic cerebral edema (Figure). It also showed partial bilateral uncal herniation and effacement of the suprasellar cistern. Bilateral low attenuation of frontal and occipital lobes was noted. This was most likely the result of marked edema presumed to be related to posterior reversible encephalopathy syndrome (PRES).

The development of focal neurologic deficits postpartum is uncommon. Differential diagnoses include seizures, posterior circulation stroke, cerebral venous thrombosis, complicated migraine, eclampsia, encephalitis, vasculitis, cerebral artery dissection, and PRES.

Key Points: The reported incidence of PRES is approximately 0.01%. PRES is a cliniconeuroradiologic entity. Clinical features include headache, confusion, seizures, cortical visual disturbances, and altered metal status. Radiologic findings include bilateral white and gray matter changes that predominantly affect the posterior cerebral hemispheres. Common causes include hypertension, preeclampsia/eclampsia, uremia, immunosuppressive drugs, transplantation, and SLE.

Eclamptic patients with atypical features such as focal neurologic deficits, markedly depressed mental status, and profound visual disturbances should be evaluated by neuroimaging. CT in this setting may help differentiate PRES from stroke. PRES is a reversible syndrome with excellent recovery in most patients within a few weeks. Early and accurate diagnosis helps ensure optimal outcomes.

Case and photo courtesy of Ranjita Pallavi, MD and Hossam Amin, MD.

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Patent Foramen Ovale and Paradoxical Stroke in a Young Cyclist

A 42-year-old man presented to the ED after multiple episodes of difficulty in speaking. For 24 hours, he had been unable to formulate his speech for 1 to 2 minutes per episode but was aware of what he wanted to say. He had experienced a similar episode 2 weeks earlier when he lost the ability to verbalize his thoughts for nearly 5 minutes. Three years earlier, he had a DVT that was treated with anticoagulation.

CT angiography of the head was unremarkable and MRA of the neck with contrast found no signs of stenosis, thrombosis, or dissection. Subsequent MRI of the brain with contrast indicated a subacute infarct. An ID workup was normal and ruled out focal encephalitis. MRI spectroscopy verified an ischemic infarct (Figure on left). Additional studies to identify the cause of infarct included TEE, which showed a patent foramen ovale (PFO) (Figure on right). Lower extremity venous Doppler ultrasonography was negative for DVT.

Key Points: PFO is not considered a primary cause of stroke. Cardioembolic events account for 19% and carotid disease accounts for 15% of ischemic strokes; the remainder are cryptogenic. Approximately 40% of cryptogenic ischemic strokes are attributed to PFO. PFO can be detected in 10% to 15% of the population by transthoracic echocardiogram.

A number of pathologic manifestations of PFO have been recently identified, including paradoxical systemic embolism. Neurologic decompression illness and migraine with aura also have been associated with PFO but are not common findings. Most patients with PFO remain asymptomatic because under normal physiologic conditions, PFO allows a small amount of left-to-right shunting without causing significant hemodynamic change. Consequently, neurologic deficits associated with PFO are rare.

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Lhermitte-Duclos Disease

A 39-year-old woman presented with a 2-month history of progressively worsening headache and right-sided ataxia. She had no significant past medical history and took no medications. Neurologic examination revealed mild dysmetria, and dysdiadochokinesia on the right side. Motor power was grade 5/5 for all extremities. Pain perception and proprioception were intact. MRI of the brain demonstrated a 4.5-cm, non-enhancing, T1 hypointense mass on the right cerebellar hemisphere (Figure), a finding consistent with Lhermitte-Duclos disease. Histopathology following surgical resection of the mass confirmed this diagnosis.

Also known as dysplastic gangliocytoma of the cerebellum, LDD is a rare, slow-growing, hamartomatous tumor of the cerebellar cortex. It is often asymptomatic in early life but usually becomes clinically apparent in the third and fourth decades. Its manifestations are usually related to a posterior fossa mass-effect and the secondary obstructive hydrocephalus that follows. The most frequent complaints are headaches and ataxia. Cerebellar signs and symptoms are seen in roughly half of patients and may be present for years before diagnosis. One-third of patients have associated cranial nerve palsies and long tract dysfunction. Less commonly presenting features are visual problems, neck stiffness, vertigo, and subarachnoid hemorrhage.

Key Point: LDD has been linked in 40% of cases to Cowden syndrome. Because of this association, concomitant malignancies, particularly breast and pelvic cancers, need to be excluded.

Case and image courtesy of Wikrom Warunyuwong, MD and colleagues

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Bilateral Corpus Callosum Stroke

A 47-year-old man who chronically abused cocaine and alcohol presented with a 3-day history of right-sided weakness and numbness. CT scan of the brain showed a left anterior cerebral artery ischemic stroke.

Examination revealed right facial weakness; motor strength was 4/5 in the right upper extremity and 3/5 in the right lower extremity. Initial lab results were unremarkable. The patient was admitted for observation and later transferred for inpatient rehabilitation, when he became aphasic and lethargic. A second CT brain scan showed a bilateral corpus callosum lesion (Figure).

Bilateral strokes of the corpus callosum are uncommon because of the rich blood supply of this structure from 3 main arterial systems-the anterior communicating, anterior cerebral, and posterior cerebral arteries. Also, the corpus callosum is a dense white matter tract, which makes it less sensitive to ischemic injury than gray matter. Moreover, the penetrating arteries of corpus callosum run perpendicular to the parent artery, thus protecting it from emboli.

Corpus callosum infarcts may present acutely or with slowly evolving and non-localizing neurologic signs and symptoms that suggest the diagnosis of tumor rather than infarct. They may exhibit radiologic features more often associated with neoplasm (eg, mass-like enhancement or extension across the midline) that prompt further radiologic imaging, such as MRI or MRA, and in some cases even a brain biopsy for definitive diagnosis.

Key Point: Biopsy may be avoided if clinicians are aware of this entity and use various radiographic studies such as diffusion-weighted imaging, perfusion imaging, magnetic resonance spectroscopy, and MRA to better delineate the lesions. Keep bilateral corpus callosum stroke in the differential diagnosis of bilateral lesions detected on radiologic imaging in patients who have bilateral neurologic features.

Case and images courtesy Ranjita Pallavi, MD and Shobhana Chaudhari, MD.

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Relapsing-remitting Multiple Sclerosis as Seen on MRI

Serial axial T2-weighted (top row) and post-contrast T1-weighted (bottom row) spin-echo MRIs of brain performed at baseline, month 1, and month 2, in a patient with relapsing-remitting MS. Multiple hyperintense lesions, which suggest multifocal white-matter pathology, are visible on T2-weighted image at baseline. On post-contrast T1-weighted examination, some of these lesions are contrast-enhanced, which indicates local disruption of blood–brain barrier. New contrast-enhancing lesions can be observed at month 1 and month 2, which indicate dissemination of disease.

Key Point: MRI has become central to the diagnosis of MS. Roughly 90% of all MS diagnoses are now based on MRI findings, because of the modality’s high sensensitivy to inflammation and demyelinating plaques.