Cerebral cavernous malformation (CCM), also known as cavernous angioma, cavernous haemangioma, and cavernoma, is a vascular disorder of the central nervous system that may appear either sporadically or exhibit autosomal dominant inheritance. The incidence in the general population is between 0.1-0.5%, and clinical symptoms typically appear between 30 to 50 years of age. Once thought to be strictly congenital, these vascular lesions have been found to occur de novo.

This disease is characterized by grossly dilated blood vessels with a single layer of endothelium and an absence of neuronal tissue within the lesions. These thinly-walled vessels resemble sinusoidal cavities filled with stagnant blood. Blood vessels in patients with CCM can range from a few millimeters to several centimeters in diameter. CCM lesions commonly resemble raspberries in external structure.

Many patients live their whole life without knowing they have a cerebral cavernous malformation. Other patients can have severe symptoms like seizures, headaches, paralysis, bleeding in the brain (cerebral hemorrhage), and even death. The nature and severity severity of the symptoms depend on the lesion's location in the brain. Approximately 70% of these lesions occur in the supratentorial region of the brain; the remaining 30% occur in the infratentorial region.

Symptoms and Diagnosis

Clinical symptoms of this disease include recurrent headaches, focal neurological deficits, hemorrahagic stroke, and seizures, but CCM can also be asymptomatic. Diagnosis is most commonly made by magnetic resonance imaging MRI, but not all MRI exams are created equal. It's paramount that the patient request a gradient-echo MRI (aka T2-Flair) in order to unmask small or punctate lesions which may otherwise remain undetected. Sometimes quiescent CCMs can be revealed as incidental findings during MRI exams ordered for other reasons.

Sometimes the lesion appearance imaged by MRI remains inconclusive. Consequently neurosurgeons will order a cerebral angiogram or magnetic resonance angiogram (MRA). Since CCMs are low flow lesions (they are hooked into the venous side of the circulatory system), they will be angiographically occult (invisible). If a lesion is discernable via angiogram in the same location as in the MRI, then an arteriovenous malformation (AVM) becomes the primary concern.

CCMs & Venous Malformations

Many times a CCM is accompanied by a venous malformation (VM) which are also known as a developmental venous anomaly (DVA). These lesions appear either as enhancing linear blood vessels or caput medusae--a radial orientation of small vessels that resemble the hair of Medusa from Greek Mythology. These are normally benign lesions that provide normal brain drainage into the venous system. Conventional wisdom recommends leaving these lesions alone, even if surgical removal of the CCM is advocated.

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Cavernous haemangioma mimicking multiple sclerosis
From British Medical Journal, 6/12/99 by M Zameel Cader

Patients diagnosed with multiple sclerosis before the advent of magnetic resonance imaging and whose symptoms could be attributable cavernous haemangioma should be reviewed with magnetic resonance imaging

Cavernous haemangiomas are vascular malformations that rarely affect the brain, but their clinical presentation can simulate multiple sclerosis. The likelihood of mistaking cavernous haemangioma for multiple sclerosis is increased further by the fact that cavernous haemangiomas are poorly identified by angiography, and even computed tomography has a relatively low sensitivity and specificity for these lesions.[1] However, high field magnetic resonance imaging is able to distinguish cavernous haemangiomas, and since its introduction increasing numbers have been reported.[1]

We describe two patients who had been diagnosed as having multiple sclerosis many years before the widespread use of computed tomography or the advent of magnetic resonance imaging. Magnetic resonance imaging subsequently showed that they had cavernous haemangioma.

Case reports

Case 1

A 17 year old boy presented in 1975 with diplopia, left sided facial weakness, and dizziness. He was fight handed. Physical examination showed that he had left VI nerve palsy and mild weakness of the lower left side of his face. The patient was admitted to hospital for further investigation. A lumbar puncture showed clear cerebrospinal fluid under normal pressure but a slightly high [Gamma] globulin fraction (0.04 g/l; 12.1% of total protein), a red cell count of 4 x [10.sup.9]/l, and a white cell count of 1 x [10.sup.9]/l.

The patient's facial weakness resolved over several months, but the left VI nerve palsy persisted. About eight months after his initial presentation, he had a further episode of neurological dysfunction with numbness of the fight hand. He had reduced sensations of light touch and pain, and a lumbar puncture again showed an increased [Gamma] globulin fraction. One month later, the numbness in the fight hand had resolved, but the palsy in the left VI nerve remained unchanged. A diagnosis of probable multiple sclerosis was made.

The patient had no further problems until he was 34 years old, when he presented with numbness of the right hand and left side of the face and impaired balance. Physical examination showed a subjective sensory disturbance in the right hand, continuing palsy of the left VI nerve, and considerably reduced visual acuity in the left eye.

Electrophysiological studies, computed tomography, and magnetic resonance imaging were arranged. Visual stimuli either failed to evoke recordable cortical responses or produced abnormal waveforms on both sides. Stimulation of the left median nerve produced well formed responses at the cervical cord, but a poor cortical response. Stimulation of the fight median nerve produced poor responses at the cervical cord and the cerebral cortex. Computed tomography showed hyperdense, ill defined lesions with irregular calcification in the posterior aspect of the pons, the fight frontal lobe, and the periventricular region of the fight parietal lobe. There was no enhancement after contrast. With magnetic resonance imaging (figure), the lesions returned mixed signals, there was no surrounding cerebral oedema and no mass effect. It was concluded that this patient had multiple cavernous haemangioma.

Case 2

A 36 year old man presented to a neurologist in 1964. He was fight handed. He had a five year history of laughing without reason (which had led to considerable embarrassment) and increasing weakness of the fight arm and leg. Physical examination showed that he had a right spastic hemiparesis and a pseudobulbar palsy. No abnormalities were detected by a radioisotope scan or angiography of the brain, and multiple sclerosis was considered the most likely diagnosis.

Despite the neurological impairment, his disability over the next 15 years was slight, and he continued to work as a manager for an advertising company. However, at the age of 51, the right sided weakness and spasticity began to progress. His inappropriate laughter was also becoming more troublesome. He presented again, aged 56, when he developed a squint in his left eye. At this time physical examination showed palsy of the left VI nerve, right spastic hemiparesis, and pseudobulbar palsy. Visual evoked responses and electroencephalographic findings were normal.

The patient was not seen again until he was 68, when he asked about the possibility of treatment with interferon beta. At this stage he was very disabled--he could walk only 15 yards with tripod support. Magnetic resonance imaging was arranged to confirm the diagnosis of multiple sclerosis. However, this showed a large, well circumscribed mass in the lower pons and upper medulla that returned mixed signals. There was no surrounding oedema and no mass effect. It was concluded that he had a large cavernous haemangioma.

Discussion

Cavernous haemangiomas are an irregular honeycomb of thin-walled vascular spaces without intervening brain tissue, and usually without any increase in the vascularity of adjacent tissues. The lesions generally occur singly. Only a few are infratentorial, and the pons is the commonest site in these cases. Cavernous haemangiomas usually manifest with the effects of a space occupying lesion or from spontaneous haemorrhage.[2]

However, there have been several published reports of vascular malformations of the brain stem. that run a long, insidious course and simulate multiple sclerosis.[3-5] Cavernous haemangiomas are not usually visualised by angiography because the blood flow through them is slow.[6] Nor is computed tomography able to identify reliably all cavernous haemangiomas. A misdiagnosis of multiple sclerosis was therefore a particular hazard before magnetic resonance imaging became widely available.

It is interesting that patient I had a high [Gamma] globulin fraction--a finding that would be consistent with multiple sclerosis. A recent case report describes a patient who was thought to have multiple sclerosis on the basis of an insidious history, negative computed tomographic findings, cerebrospinal fluid with oligoclonal bands, and (later) a raised [Gamma] globulin fraction.[3] These authors noted that oligoclonal bands and raised [Gamma] globulin values are sensitive, but not specific, for multiple sclerosis.

The clinical distinction between cavernous haemangiomas and multiple sclerosis affecting the brain stem is sometimes difficult. In neither of our patients was there an obvious episode of optic neuritis or any disordered eye movement other than the VI nerve palsy--findings that would have been unusual for multiple sclerosis. In both our patients, the initial clinical picture could have been attributed to a single brain stem lesion. In these cases there should be a high index of suspicion for a structural lesion. However, cavernous haemangioma can occasionally be multiple. This adds to the difficulty in making a diagnosis and supports the value of magnetic resonance imaging in confirming a diagnosis of multiple sclerosis.

Abnormal findings in cerebrospinal fluid and results of electrophysiological studies are clearly non-specific. However, with the increasing use of magnetic resonance imaging for detecting white matter plaques when multiple sclerosis is suspected, differentiating between the two abnormalities should not pose a problem. For patients diagnosed as having multiple sclerosis before the advent of modern imaging technologies, particularly those whose symptoms could be attributable to single lesions, the diagnosis should be reviewed carefully.

We thank Dr R Hughes and Professor A C Williams.

[1] Curling OD, Kelly DL, Elster AD, Craven TE. An analysis of the natural history of cavernous angioma. J Neurosurg 1991;75:702-8.

[2] Russell DS, Rubinstein LJ. Pathology of tumours of the nervous system. 5th ed. London: Edward Arnold, 1989.

[3] Vrethem M, Thomas KA, Hillman J. Cavernous angioma of the brain stem mimicking multiple sclerosis [letter]. N Engl J Med 1997;336:875-6.

[4] Honczarenko K, Fryze C, Nowacki P, Osuch Z, Grzelec H, Fabian A. Cavernous angioma of brain stem mimicking multiple sclerosis. Folia Neuropatholigica 1995;33:251-4.

[5] Stahl SM, Johnson KP, Malamud N. The clinical and pathological spectrum of brain stem vascular malformations. Long term course stimulates multiple sclerosis. Arch Neurol 1980;37:25-9.

[6] Requena I, Arias M, Lopez-Ibor L, Pereiro I, Barba A, Alonso A, et al. Cavernomas of the central nervous system: clinical and neuroimaging manifestations in 47 patients. J Neurol Neurosurg Psychiatry 1991;54:590-5.

(Accepted 9 November 1998)

Department of Neurology, Queen Elizabeth Hospital, Birmingham B15 2TF

M Zameel Cader, house officer

J B Winer, consultant neurologist

Correspondence to: Dr Winer j.b.winer@bham. ac.uk

BMJ 1999;318:1604-5

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