A cavernous angioma or cavernous malformation or cavernoma is an abnormal collection of blood vessels that is often described to mimic a “blackberry” or “mulberry” in appearance.
Cavernomas may present in any part of the body, but are particularly problematic in the brain and the spinal cord where functionally eloquent structures may be compressed by this abnormality or a subsequent bleed, due to the limited space they reside in. These malformations may be hereditary or spontaneous (‘de novo’) and grow slowly. The treatment options for these lesions can include surgery and focussed radiation therapy.
Who is affected?
Of the hereditary forms of cavernomas, the Hispanic-American communities are thought to have a slightly higher predisposition. Like cavernomas in general, there is a slight preponderance for females to be affected more than men, though there is some ambiguity as to whether gender is a risk factor at all. Spinal cavernomas may be inside the spinal cord (intramedullary) or outside the spinal cord but in the spinal bony canal (extramedullary). It is thought that approximately 85% of spinal cord cavernomas are intramedullary. The peak age groups identified with a spinal cavernoma at presentation, are patients in their 30s and 40s.
Natural Course and Presentation
How are patients affected?
Due to the limited space in the spinal cord and the severe intolerance the nerves have to any pressure being exerted on them, patients with spinal cavernomas may complain of pain in a defined nerve distribution. In cases that the pressure causes neurological (spinal cord or nerve) damage, the patient may present to the hospital with progressive functional deterioration affecting the power or sensation (‘pins and needles’, numbness) in the limbs, or bowel/bladder dysfunction.
Four main patterns of how patients are affected have been described. These include:
1) Sudden episodes of deterioration, changing the patient’s baseline functionality at each step
2) Slow progression of the patient’s deterioration
3) A single, sudden episode of deterioration, with a rapid decline
4) Sudden onset of mild symptoms with a gradual decline
It is reasonable to suppose, that those patient’s that display sudden onset rather than gradual symptoms have had an associated bleed (haemorrhage) of or around the cavernoma which accounts for the sudden (rather than gradual) compression of the spinal nerves. Days, weeks to 3-4 years may pass before a spinal cavernoma is detected, depending on the mode of presentation. Unlike brain cavernomas, it is thought that environmental factors such as trauma, strenuous activity and pregnancy may be contributory to those patients presenting with haemorrhage. The exact symptoms a patient experiences, depend entirely on which part of the spinal cord is affected; but generally, the higher in the spinal cord the abnormality is, the higher the risk for more disabling symptoms.
How are they detected?
After a thorough clinical history of the patient’s symptoms and a clinical examination to elucidate the presence of any disturbance in the nervous system, the patient may be referred for a Magnetic Resonance Imaging (MRI) scan to image the back +/- the brain (depending on the clinical findings). The images are reported by a radiologist (x-ray doctor) they are discussed at the regional neurovascular multidisciplinary team meeting. This meeting will have doctors and surgeons from all relevant specialties, who will decide the best course of treatment based on the patient’s symptoms, the imaging and the experience of the multidisciplinary team.
How are they treated?
Though no strong, class I evidence exists to compare treatment methods, spinal cavernomas may be treated with surgical excision, focused radiotherapy or conservatively with regular MRI scanning and follow up. The focused radiotherapy, also called stereotactic radiotherapy, has a limited role in the treatment of cavernomas. There is a risk of causing hazardous swelling (oedema) which cannot be tolerated in the limited space available for the spinal cord. Surgery is often curative if successful and is the option of choice for patients with haemorrhage causing sudden severe symptoms. The surgical approach involves a general anaesthetic and removal of part of the bone from the back of spinal vertebra and the associated ligaments to access the lining (dura) of the spinal cord. The abnormality in most of the cases can be identified as a discolouration on the surface of the cord caused by blood and blood products. The abnormal connection is then identified and disconnected. Intra-operative neurophysiology is a technique valued by surgeons whilst operating to help detect electrical activity in ambiguous tissue that may have function for a patient, before sacrificing it. It can also help detect how much manipulation various parts of the spinal cord can tolerate before causing lasting damage.
Outcome and Prognosis
How do patients do?
In the literature, approximately two-thirds of patients undergoing surgical resection for spinal intramedullary cavernoma show improvement from their presenting symptoms. There seems to be no correlation of better outcome with patient’s age, gender, lesion size, location in the neck or the upper back or severity of deterioration. There is, however, a correlation of worse outcome in patients with anterior (in front) cord cavernomas. There is evidence to suggest that after surgery, three-quarters of patients with symptoms less than three years show improvement versus half of those with symptoms for more than three years. Patients with bowel/bladder disturbance tend to have partial, if any, resolution of symptoms at all.
Special thanks to Mr Nikolaos Tzerakis*, consultant neurosurgeon, University Hospital of North Staffordshire and Dr I.Z. Haq, Specialist trainee in neurosurgery, University Hospital of North Staffordshire for providing the above article.