MRI demonstration of a reversible lesion in cerebral deep white matter in thrombotic thrombocytopenic purpura

Cerebral Microangiopathy in Two Dogs with Cutaneous and Renal Glomerular Vasculopathy

Cutaneous and renal glomerular vasculopathy (CRGV) is an emerging disease in the UK, but its aetiology remains unclear. It is considered a thrombotic microangiopathy (TMA) in which the kidney and skin are the most commonly affected organs. We now document two cases of CRGV with brain lesions, which may have accounted for neurological signs displayed by these animals. The histopathological brain lesions were similar to TMA lesions in humans with thrombotic thrombocytopaenic purpura (TTP) and complement-mediated haemolytic uraemic syndrome (CM-HUS), in which the neurological signs are more associated with TMA than with any systemic disease or electrolyte imbalance. Fibrinoid necrosis in brain arterioles and associated lesions in these dogs were similar to those in human CM-HUS, indicating that the alternative complement pathway may play an important role in the pathophysiology of CRGV.

Central-variant posterior reversible encephalopathy syndrome: brainstem or basal ganglia involvement lacking cortical or subcortical cerebral edema

OBJECTIVE

Although posterior reversible encephalopathy syndrome (PRES) typically involves cortical or subcortical edema of the cerebrum, only individual cases have been described of a variant involving the central brainstem and basal ganglia and lacking cortical and subcortical edema. We evaluated FLAIR and T2-weighted images of 124 patients with confirmed PRES to determine the incidence of this uncommon variant, which we refer to as the "central variant"; to determine which structures are involved in this variant; and to determine the associated causes.

CONCLUSION

We found that five of the 124 patients (4%) with PRES had MR findings consistent with the central variant-that is, either brainstem or basal ganglia involvement and a lack of cortical or subcortical edema of the cerebrum. The thalami were involved in all five PRES patients with MR findings consistent with the central variant, but there was variable involvement of the posterior limb of the internal capsule (4/5), cerebellum (3/5), and periventricular white matter (3/5); in each patient, there was improvement both clinically and on MRI. The causes of PRES in these five patients were hypertension (n=2), cyclosporine (n=2), and eclampsia (n=1). The incidence of the central variant may be increasing because of an improving awareness of the diverse imaging patterns of PRES.

Reversible brainstem hypertensive encephalopathy (RBHE): Clinicoradiologic dissociation

We report two cases of reversible brainstem hypertensive encephalopathy (RBHE) with unusual magnetic resonance (MR) findings. Patient 1, an 85-year-old man without a history of hypertension, developed acute severe hypertension and mild consciousness disturbance as the only symptoms. Patient 2, a 46-year-old man with an untreated hypertension, presented with extremely high blood pressure and general fatigue, vertigo, and mild dysarthria as the initial manifestations. In these patients, fluid-attenuated inversion recovery (FLAIR) and T2-weighted MR images revealed diffuse hyperintensities in the brainstem. Diffusion-weighted imaging (DWI) findings were normal, and apparent diffusion coefficient (ADC) values were increased in the brainstem. The supratentorial regions were largely spared, and mildly diffuse hyperintensities were noted in the white matter. There were no accompanying changes in the occipital lobe and cerebellum. The lesions completely resolved after stabilization of blood pressure. The normal DWI findings and high ADC values were consistent with vasogenic edema due to severe hypertension. The characteristics of RBHE are a very high blood pressure, mild clinical and neurologic symptoms, rapidly improved MR findings after initial treatment with the control of hypertension, and a marked clinicoradiologic dissociation.

Upward transtentorial herniation, hydrocephalus, and cerebellar edema in hypertensive encephalopathy

BACKGROUND

Edema of the cerebellum with secondary obstructive hydrocephalus is a rare presentation of hypertensive encephalopathy. The authors report an unusual case of isolated posterior fossa swelling with upward transtentorial herniation and hydrocephalus causing neurologic deterioration. These patients are often initially evaluated by a neurologist because of the acute neurologic symptoms. Prompt diagnosis with aggressive blood pressure control may obviate the need for emergent cerebrospinal fluid (CSF) diversion.

REVIEW SUMMARY

This is a case report of a 26-year-old man who presented to the emergency room with confusion and somnolence over a 2-day period. His initial blood pressure was 175/110 mmHg. On examination he was disoriented, with a Glasgow Coma Scale score of 12 points, opening his eyes only to loud verbal stimuli, verbalizing inappropriately, and he was only able to follow simple commands. Neuroimaging revealed edema of the cerebellar folia with noncommunicating hydrocephalus and upward transtentorial herniation. Differential diagnoses of posterior fossa tumor, rhombencephalitis, and hypertensive encephalopathy were entertained. A thorough literature review is included with the discussion of this case. The patient underwent emergent ventriculostomy for CSF drainage and prompt blood pressure control with nitroprusside. After 48 hours of CSF drainage and correction of his hypertension, his neurologic examination normalized. Repeat imaging revealed near resolution of the obstructive hydrocephalus and cerebellar edema.

CONCLUSION

Isolated edema of the cerebellum with upward transtentorial herniation and obstructive hydrocephalus is a rare presentation of hypertensive encephalopathy and should be considered in patients with an acute hypertensive crisis and mental status changes. This entity responds to prompt blood pressure control; however, emergent ventriculostomy by a neurosurgical team should be entertained for neurologic deterioration secondary to significant obstructive hydrocephalus, as illustrated in this case.

Thrombotic microangiopathy (TMA) and stroke due to human herpesvirus-6 (HHV-6) reactivation in an adult receiving high-dose melphalan with autologous peripheral stem cell transplantation

We report an adult autologous stem cell transplant (ASCT) patient who developed transplant-associated thrombotic microangiopathy (TMA) due to human herpesvirus-6 (HHV-6) reactivation. A 58-year-old female with Stage IIIA IgGkappa multiple myeloma received a melphalan (200 mg/m2) ASCT with discharge home after resolution of ASCT-related toxicities. She presented on D+20 with dyspnea, rash, and fever to 105 degrees F, followed by worsening dyspnea, hypotension, and capillary leak. Mental status (MS) changes were noted on D+23, but head CT and EEG were unremarkable. On D+29, a generalized seizure occurred with decline in platelet count and haptoglobin. TMA was noted on peripheral blood smear and therapeutic plasma exchange (TPE) was initiated on D+31. Lumbar puncture (LP) revealed CSF protein 74 mg/dL and white blood count 7,000/mm3 with 74% lymphocytosis. TPE was continued without improvement in her MS or thrombocytopenia despite improvement in microangiopathy. An MRI of the brain showed a left hippocampus abnormality, and an EEG was consistent with encephalopathy. Serum polymerase chain regimen (PCR) was negative for CMV, HSV1, and HSV2 but was strongly positive for HHV-6. Repeat LP protein was 597 mg/dL. Foscarnet was initiated, and cerebrospinal fluid (CSF) PCR for HHV-6 revealed 1,400 DNA copies/mL. Her MS greatly improved within 48 hr of antiviral therapy, serum HHV-6 became negative, and TPE was tapered without recurrence of her TMA. TMA with HHV-6 reactivation is likely an underdiagnosed entity. Given its fulminant course and favorable response to therapy, HHV-6 reactivation should be considered a potential etiology in patients with TMA after ASCT.

Thrombocytopenic thrombotic purpura: severe clinic with no CT, minor MRI, but a SPECT correlate

A 28-year-old woman with primarily therapy refractory TTP was followed neuroradiologically over 6 months. Despite pronounced neurological and neuropsychiatric symptoms including hemiparesis and aphasia she had unremarkable CT scans on two occasions. Three MRI exams showed no correlate for her neurological symptoms except a small petechial cortical hemorrhage in the right parietooccipital gyrus which may account for her TTP-related anxiety disorder. A cerebral HMPAO-SPECT showed long-standing right-sided hypoperfusion compatible with residual vasculature changes. The possible causes for the clinico-neuroradiological discrepancies are discussed in view of the literature.

Eclamptic encephalopathy: imaging and pathogenetic considerations

Eclampsia is a rare condition peculiar to pregnant and puerperal women, characterized by clinical pre-eclampsia (hypertension, proteinuria, edema) and generalized seizures. Three cases of eclamptic encephalopathy are reported: CT and MRI demonstrated transient abnormalities in the cortical and subcortical regions of the posterior areas of the brain - namely, parieto-occipital lobes - associated with occasional involvement of basal ganglia and/or brainstem. Pathogenesis is still unclear. Strict similarity with the pathological findings characterizing hypertensive encephalopathy suggests that a focal impairment in cerebral autoregulation may be the cause of vasodilation and fluid extravasation leading to hydrostatic edema; selective involvement of posterior areas could be explained by their lesser degree of adrenergic innervation supporting circulatory autoregulation mechanisms.