A birthmark usually in the face called port-wine mark or nevus flammeus is the most observable early symptom [9]. The appearance of the birthmark are of different  colors (pink, red or dark purple) and sizes. Most often, one of the eyelids are affected and/or one of the frontal part of the head, and less commonly in both sides of the face. Sometimes, this discoloration may be seen covering a half of the face, or extend slightly across the plane of the face. Also, part of the trunk or arms may be affected. Port-wine birthmark associated with SWS results from increased plexus of capillaries beneath the skin surface in the arrangement of trigeminal nerve. Capillaries are network of small blood vessels that connect arteries or veins and are involved in the exchange of blood nutrients including oxygen within cells and tissue. Untreated port-wine birthmarks becomes more thickened and deepened in color with age, sometimes develop into blood blisters (blebs), which could cause spontaneously bleeding (blebbing).

Patients with SWS usually present with varying forms of neurological abnormalities [10], the extent of which differs from patient to patient. Neurological symptoms result from abnormal development of blood vessels in the brain (a condition called leptomeningeal angiomas). Common symptoms include seizures, which often starts during infancy or childhood. Like the port-wine birthmark, the seizures may affect the different or all part of body side.

Other symptoms include, headaches, visual field defects particularly vision impairment in either one or both eyes (a condition called hemaniopsia), stroke or stroke-like episodes (transient ischemic attacks). Also, a noticeable behavioral problems which include, attention deficit disorder, psychological disorders, and poor social skills are observed in some of the affected children, particularly those with repeated seizures and reduced cognitive function.

Glaucoma [11], a condition characterized by marked increase in eye pressure is seen in children at birth. This may affect the eye on the affected side of the face with port-wine birthmark.

Other eye defects commonly associated with SWS include, angiomas of the conjunctiva, blood vessel and choroid between the sclera, retina, and cornea. The eye shows feature of double color (e.g. a brown or blue). Also, there could be abnormal accumulation of fluid in the eye resulting in enlargement of the fibrous coat of the eyeball (condition known as hydrophthalmos), optic atrophy, retinal detachment, angioid streak, and/or cortical blindness. Most patient that develop neurological defect without port-wine birthmark manifestation generally do not show signs of eye problems.

• Epilepsy

  At Boston Children’s Hospital, Sturge-Weber patients donated their brain tissue to research after it was removed during a drastic surgery to treat severe epilepsy. [vector.childrenshospital.org]

  Patients without epilepsy were compared with patients with epilepsy based on the location of the port-wine stain, its extent and cerebral imaging. RESULTS: Twenty-four patients were included in the study. Thirteen did not develop epilepsy. [ncbi.nlm.nih.gov]

  Extensive port-wine stains are associated with a higher risk of epilepsy and glaucoma, while bilateral leptomeningeal vascular malformations are associated with learning and intellectual disability [13]. [dermnetnz.org]

• Disability

  All three may be associated with long-term normal intelligence or a varying degree of intellectual disability. [ncbi.nlm.nih.gov]

  From Wikidata Jump to navigation Jump to search a rare congenital neurological and skin disorder associated with port-wine stains of the face, glaucoma, seizures, intellectual disability, and cerebral malformations and tumors. encephalotrigeminal angiomatosis [wikidata.org]

  Some individuals have learning disabilities with problems focusing similar to attention deficit hyperactivity disorder (ADHD). [ghr.nlm.nih.gov]

  Neurologic complications of Sturge-Weber syndrome include seizures, focal neurologic deficits (eg, hemiparesis), and intellectual disability. [msdmanuals.com]

• Swelling

  She underwent right eye glaucoma drainage device surgery under general anaesthesia, and had a difficult intubation due to extensive angiomatous like soft tissue swelling at her upper airway. [ncbi.nlm.nih.gov]

  There was an erythematous swelling on left side of upper lip within the plaque suggestive of superficial hemangioma with a deep component on upper lip. Left eye showed conjunctival congestion with edema of upper lid (Figure 1). [japi.org]

  Unilateral red swelling of gingiva was clearly evident in our case. [jofs.in]

  MRI or if MRI is not available findings tram-tracking sign caused by brain calcifications Differential Klippel-Trenaunay-Weber syndrome distinguishing factors associated with port-wine stains patients present with varicose veins, bone and soft tissue swelling [step2.medbullets.com]

• Fever

  We have learned that fevers or sickness can wreak havoc on her system and very possibly started her into a downward spiral. My heart breaks to think that she was never held during times like this. This is what we now know. [nohandsbutours.com]

  The initial seizures often involve the hemibody contralateral to the pial angioma and early seizures are triggered by fever in about one third of cases (8). Almost all the early seizures qualify as status epilepticus. [synapse.koreamed.org]

  Seizures began during a febrile illness in 10 patients (31%; fever could be a precipitant at any age), while infantile spasms occurred in 2 patients (6%). [39] Developmental delay In the patients reported by the Sturge-Weber Foundation, 50% had complete [emedicine.medscape.com]

• Asymptomatic

  It is estimated that approximately one in two adults with Sturge–Weber syndrome have neurological defects, even in those who were initially asymptomatic. [dermnetnz.org]

  The patient remained asymptomatic at a year of follow-up. Encephalotrigeminal angiomatosis or SWS is an uncommon neurocutaneous syndrome affecting brain microvasculature that presents sporadically and is usually diagnosed in childhood. [elsevier.es]

  Choroidal hemangiomas are present in 20%–70% of cases, and the choroid may become significantly thickened and can be associated with an increased risk of glaucoma development. 29 Choroidal hemangiomas may be asymptomatic; however, severe forms may lead [dovepress.com]

• Vascular Disease

  Aspirin can be advised for headache and to prevent vascular disease [16]. Eye drops are prescribed for glaucoma. Dental management of the patient should be stressed on behavior management and preventive measures. [hindawi.com]

  These "stroke like episodes" occurred in 14 of 20 patients as reported by Maria et al. [9] Headaches are more likely seen in patients with bilateral involvement and occur secondary to vascular disease, giving symptoms of a migraine headache, considered [jofs.in]

  These conditions occur in 50-60% of patients and are more likely in patients with bilateral involvement. [ 1, 3, 5 ] Headaches occur secondary to vascular disease. The symptoms are similar to a migraine headache. [patient.info]

  Good seizure control and only mild to moderate developmental impairment was seen in about 50% of the patients with bilateral SWS. [47] Headaches Occurring secondary to vascular disease, these have the symptoms of a migraine headache and are considered [emedicine.medscape.com]

• Muscle Weakness

  There may be muscle weakness on the same side. Some children will have developmental delays and mental retardation; most will have glaucoma (increased pressure within the eye) at birth or developing later. [medicalmarijuana.com]

  Physical therapy should be considered for infants and children with muscle weakness. Educational therapy is often prescribed for those with impaired cognition or developmental delays. [ninds.nih.gov]

  There may also be muscle weakness on the side of the body opposite the birthmark. [en.wikipedia.org]

• Hemianopsia

  The pain severity was reduced and the duration of headache with homonymous hemianopsia was shortened from several days to several hours. Interestingly, naratriptan also shortened the duration of homonymous hemianopsia to several hours. [ncbi.nlm.nih.gov]

  However, Jung et al reported a case of a woman with headache and left hemiparesis but no neuroimaging evidence of acute thrombosis formation or recent vascular event. [43] Hemianopsia The mechanism for hemianopsia is similar to that for hemiparesis and [emedicine.medscape.com]

• Visual Impairment

  Abstract Visual functions in Sturge-Weber syndrome (SWS) may be impaired by glaucoma, diffuse choroidal haemangioma (DCH) or leptomeningeal angioma. The aim of this study was to gain better insight in the visual deficits of SWS patients. [ncbi.nlm.nih.gov]

  Your child may be taught braille, screen-reading software to use the computer, and techniques for performing life skills and academic tasks from the Teacher of Students With Visual Impairments and Orientation and Mobility Specialist. [afb.org]

  This may be present at birth and may cause visual impairment if not treated. All children with SWS should be referred to a specialist in eye disorders in children (a paediatric ophthalmologist). [epilepsy.org.uk]

  […] loss in SWS patients is mainly related to glaucoma development, but choroidal hemangiomas may also lead to visual impairment thorough exudative retinal detachment and macular edema. [dovepress.com]

• Visual Impairment

  Abstract Visual functions in Sturge-Weber syndrome (SWS) may be impaired by glaucoma, diffuse choroidal haemangioma (DCH) or leptomeningeal angioma. The aim of this study was to gain better insight in the visual deficits of SWS patients. [ncbi.nlm.nih.gov]

  Your child may be taught braille, screen-reading software to use the computer, and techniques for performing life skills and academic tasks from the Teacher of Students With Visual Impairments and Orientation and Mobility Specialist. [afb.org]

  This may be present at birth and may cause visual impairment if not treated. All children with SWS should be referred to a specialist in eye disorders in children (a paediatric ophthalmologist). [epilepsy.org.uk]

  […] loss in SWS patients is mainly related to glaucoma development, but choroidal hemangiomas may also lead to visual impairment thorough exudative retinal detachment and macular edema. [dovepress.com]

• Eruptions

  Unilateral hypertrophy of alveolus, pyogenic granuloma, ipsilateral premature eruption or delayed eruption, and malocclusion are the other abnormalities reported [14]. [hindawi.com]

  Other signs and symptoms of SWS can include intellectual disabilities, learning disabilities, attention deficit/hyperactivity disorder, headaches or migraines, unusual eruption of teeth or premature loss of teeth. [epilepsy.com]

  Oral hygiene was adequate and as such there was no obvious discrepancy in the pattern of tooth eruption. Radiograph showed the presence of tramline gyriform calcification in the occipital region [Figure 3]. [jofs.in]

• Seizure

  Seizures: When a child presents with a new-onset seizure, a neurologic consultation should be sought. [hemifoundation.homestead.com]

  Seizures - When a child presents with a new-onset seizure, a neurologic consultation should be sought. [sturge-weber.org]

  Brain surgery involving removing the portion of the brain that is affected by the disorder can be successful in controlling the seizures so that the patient has only a few seizures that are much less intense than pre-surgery. [en.wikipedia.org]

• Convulsions

  Convulsions usually happen on the side of the body opposite the birthmark and vary in severity. There may be muscle weakness on the same side. [medicalmarijuana.com]

  A case of 23 years old female presented with history of tonic-clonic convulsions, evidence of Port wine stain on face since birth, characteristic CT findings diagnosed as a case of Sturge Weber Syndrome is reported here for its rarity. [ncbi.nlm.nih.gov]

  The convulsions usually appear on the opposite side of the body from the Port Wine Stain and vary in severity. Vigorous attempts are made to control the seizures with medication. [hemifoundation.homestead.com]

  […] of epileptic convulsions and her skull radiograph showed intracranial calcification in the occipito-parietal region. [casereports.bmj.com]

  Convulsions, or seizures, often appear before the age of 12 months, and they may worsen with age. Infants who have seizures before the age of 2 years may also have learning difficulties. [medicalnewstoday.com]

• Cerebral Calcification

  These included cerebral atrophy (81.82%), cerebral calcification (54.55%), leptomeningeal angioma (27.27%), and enlarged choroidal plexus (27.27%). The ocular complication and intracranial abnormalities were usually ipsilateral to the PWS. [ncbi.nlm.nih.gov]

  […] blood vessel growth occurs in some parts of the body but not in others. angiomatosis aculoorbital-thalamic syndrome encephalofacial hemangiomatosis encephalofacial hemangiomatosis syndrome meningo-oculo-facial angiomatosis meningofacial angiomatosis-cerebral [ghr.nlm.nih.gov]

  CT scan showed left cerebral hemiatrophy, left frontal and parieto occipital calcification with cortical calcification in left high frontal convexity. [degruyter.com]

  In 1912 Weber and Volland described the intracranial calcification. Radiographic identification of cerebral calcification was first described by Dimitri in 1922 2,18,20. [radiopaedia.org]

• Focal Seizure

  Here, we present an interesting case of SWS type 3 where a child presented twice with prolonged severe unilateral headache mimicking migraine status followed on both occasions with focal seizures. [ncbi.nlm.nih.gov]

  The seizures usually involve only one side of the brain (focal seizures), during which the port-wine birthmark may darken and individuals may lose consciousness. [ghr.nlm.nih.gov]

  Ictal Focal rhythmic epileptiform discharges occur during focal seizures, with spatial correlation with the leptomeningeal angioma. [epilepsydiagnosis.org]

  […] lesion responsible for epilepsy in SWS is focal, the majority of seizures are focal seizures. [emedicine.medscape.com]

• Hyperactivity

  Stimulant medication may be a safe and effective intervention for Sturge-Weber syndrome children with attention issues/attention deficit hyperactivity disorder. Further studies with larger sample sizes are needed. Copyright © 2014 Elsevier Inc. [ncbi.nlm.nih.gov]

  Some individuals have learning disabilities with problems focusing similar to attention deficit hyperactivity disorder (ADHD). [ghr.nlm.nih.gov]

  + Signs and symptoms  Developmental delay/mental retardation  Learning problems  Attention deficit-hyperactivity disorder  Hemangiomalike, superficial changes (which on histology demonstrate only venous dilation) in the eyelid  Buphthalmos  Glaucoma [slideshare.net]

  Other signs and symptoms of SWS can include intellectual disabilities, learning disabilities, attention deficit/hyperactivity disorder, headaches or migraines, unusual eruption of teeth or premature loss of teeth. [epilepsy.com]

  Taking the mental delays into account, behaviors associated with attention-deficit hyperactivity disorder (ADHD) were noted; as it turns out, about 22% of people with SWS are eventually diagnosed with ADHD. [encyclopedia.com]

Apart from the general clinical examination of patient for signs and symptoms of SWS, other investigation historically used in establishing diagnosis include [11] [12],

• Skull X-ray
• Angiogram
• CT scanning
• Normal Magnetic Resonance Imaging (MRI) or with the use of a contrasting medium such as gadolinium
• Specialized imaging technique such as single-photon emission computed tomography (SPECT) or positron emission tomography (PET).

The main diagnostic challenge is the differential test to identify a child with only facial port-wine birthmark presentation from others with brain and/or eye associated with SWS. Clinical conditions such as megalencephaly-capillary malformation-polymicrogyria (MCAP) and Klippel-Trénaunay syndromes (KTS) may share similar features as SWS .

Recent report suggested that prenatal diagnosis is possible using ultrasound or MRI which may reveal hemispheric changes (unilateral gyriform calcification or focal atrophy) in white matter of the brain.

• Hypsarrhythmia

  Hypsarrhythmia can be seen in those with epileptic spasms. Activation EEG abnormality is enhanced by sleep deprivation and in sleep. [epilepsydiagnosis.org]

Treatment of Sturge-Weber syndrome include;

• Use of anticonvulsants to manage seizure.
• Appropriate treatment of underlying symptoms like headache.
• The use of prophylactic agent for glaucoma treatment to suppress intraocular pressure (IOP),
• Laser therapy to remove port-wine stain (PWS).

Treatment of seizures in SWS cases usually involves an anti-convulsant medications, the efficacy of which varies from one to another. Some patient may not respond to this medications, particularly in cases of refractory seizures despite the intense regimen. Refractory seizures cases, glaucoma, and other disorders associated with SWS including scoliosis [13], are managed by surgical techniques. The surgical procedures may include, hemispherectomy, vagal nerve stimulation (VNS) or focal cortical resection.

Laser therapy is an effective procedure, which can be used to lighten or erase body port-wine birthmark even in 4- weeks old infants. However, this birthmarks may reoccur or become more darker after the initial treatment, which may therefore require multiple therapy. Port-wine stain birthmark are different either in sizes, distribution or intensity in the body, therefore effective therapy in managing patient may vary depending on the feature of the birthmark. This indicates that different laser technique may be used for the affected body parts. The most commonly known technique for treating port wine stain birthmark associated with SWS is pulse dye laser therapy.

Propranolol, verapamil and prophylactic drugs are often recommended for the treatment of ordinary headache and migrane. Also, some anti-seizure drugs (e.g gabapentin, topiramate, or valproic acid) may be effective in treating migraines or headaches.

Conventional drug treatment of glaucoma associated with SWS are usually ineffective, therefore surgical therapy are considered to be the major method of managing this condition by most opthalmologist [14].

Prognosis of SWS depends on the epileptic episode severity which may result into varying clinical presentations including psychomotor regression and intellectual impairment.

Common clinical manifestations associated with neurological and developmental morbidities in SWS include, seizures, general body weakness, strokes and headache. Some patient may have physical or mental retardation and hemianopsia.

Age is an important factor in the development or onset of seizure and a determinant of the level of neurologic involvement. Neurologic disorder increases with bilateral port wine stain. Patients may also experience severe eye complications such as refractory seizures, visual loss or blindness due to glaucoma. Some may have cosmetic deformities and other soft-tissue diseases.

Glaucoma develops in 30-71% of patients diagnosed with Sturge-Weber syndrome. The morbidity often seen in SWS due to glaucoma results from early onset of the condition and its resistance to conventional forms of therapy.

SWS results from genetic mutation in a gene called GNAQ [2]. This mutation is somatic in nature since it develops following fertilization of the embryo (mutation of GNAQ in SWS occur in early embryonic stage). Somatic mutation affects all body cell other than the sex cells (i.e sperm and egg cells). This result in different cells carrying varying copies of normal and mutated gene, (mosaic mutation pattern). This genetic pattern is one of the causes of variation in the symptoms of SWS, due to the difference in the number and types of affected cell. Somatic mutations are not hereditically transmitted, therefore not  transferable to children. Some studies suggested that somatic mutations involving GNAQ gene occur rarely without any underlying cause.

Genes encodes information for synthesis of protein that are important in various body activities. When genetic mutation occurs, the synthesized protein product may be reduced, inactive or absent. Depending on the affected protein, different organs in the body may be affected. GNAQ gene synthesizes a protein called Gaq that is vital in cell processes, which include control of blood vessel. The underlying factors causing alteration in Gaq protein among SWS patient is not well understood. Further studies are important to evaluate the major mechanism resulting varying symptoms associated with SWS.

As previously stated, SWS symptoms may be due to altered growth or proliferation of some specific blood vessels with secondary effects in the affected tissue. These effects include shortage of oxygen (hypoxia), ischemia and venous obstruction. Also,there may be thrombosis, infarction due to shortage of oxygen in the affected tissue. Brain calcification is also a common feature of the disease.

SWS is an uncommon disorder that usually occur at a rate of about 1 in every 50,000 individuals [1]. There are no racial differences in the incidence of the disease and are sporadically inherited. Generally, this disorder can be diagnosed at birth or early in infancy based on clinical signs and symptoms. However, morbidity which arises from complications and secondary changes persist throughout lifetime.  

SWS result from defect in the embyonal blood vessels coupled with the secondary effects on the associated brain tissue. In the cephalic end of the neural tube, plexus of blood vessels develops below ectoderm which later transforms into the facial skin. In a normal process, vascular plexus develops in the sixth week during gestational period and regresses in the ninth week. Alteration in this normal regression process leads to the formation of residual vascular tissue, which transforms into a congenital malformation such as leptomeningeal angiomatosis of the face and the ipsilateral eye.

SWS may cause neurological dysfunction due to the secondary effects on local brain tissue. This include [3] [4]:

• Ischemia which may induce hypoxia in the associated brain tissue
• Venous occlusion or obstruction caused by thrombosis
• Infarction and vasomotor phenomenon

The disease development is progressive [5] [6], with neurological manifestation. A condition known as "vascular steal phenomenon" can develop at the angioma site, causing cortical ischemia. Complications such as seizures (e.g status epilepticus, intractable and recurrent seizures) and continuous vascular events may worsening the steal condition, with rapid increase in the development of cortical ischemia. This may result into progressive brain calcification, gliosis, or atrophy of the brain tissue, which may further increases the episode of seizures and neurologic dysfunction [7] [8].

Ocular manifestations such as buphthalmos and glaucoma usually occur as a secondary effect of an increased IOP with acute-angle obstruction of the eye, raised episcleral venous pressure, and increased release of aqueous fluid.

Proper seizure management, aspirin therapy, and prompt surgical intervention may prevent neurological complications.

Currently, there is no known method to control or prevent the disease.

Features of sturge-weber syndrome include seizure, glaucoma, leptomeningeal angiomatosis of the lobes (particularly parieto-occipital lobes), vascular malformations of the intracranium and face. Ischemia associated with leptomeningeal angiomastosis is commonly observed, which often result from stasis causing necrosis and laminar calcification. There is variation in the disease development with some children presenting symptoms such as intractable seizures, frequent stroke-like episodes, and mental retardation [1].

SWS are classified into three major types:

• Type 1: This is the most common SWS. In this type, the blood vessels undergo an abnormal growth or vascular malformation of both the brain and face. It can result into seizures, usually evident in the few months of birth, and may persist throughout life time. Learning disability, delayed development, and glaucoma are associated with type 1 SWS. Glaucoma is a condition which causes increase in ocular pressure.
• Type 2: This is characterized by a special mark on the face called port wine stain and may not have any brain effect. Other symptoms such as headache, glaucoma, and changed blood flow, which may persist into adulthood.
• Type 3: This involves abnormal growth of blood vessel of the brain. In this type, visible port wine stain and glaucoma are usually absent. Type 3 may be difficult to diagnose as it is often mistaken with other conditions. Brain scans are useful in making differential diagnosis.

Sturge-Weber syndrome is an uncommon birth defect with varying clinical implications. Children born with this condition usually have distinct birthmark called port-wine stain particularly on their face with sometimes nervous system problems.

Causes
There is no known cause and any record of genetic transmission of Sturge-Weber syndrome.

Symptoms

• Port-wine stain birthmark (commonly seen on the face)
• Seizures in patient
• General paralysis or weakness on one half of the body
• Learning difficulties

Diagnosis

Clinical examination of suspected children with birthmark feature by doctor. Other special test may be requested to guide the diagnosis. This include, magnetic resonance imaging (MRI), skull x-ray and angiography. Neurological examination may also be required to determine the neurological involvement.

Treatment

Treatment of SWS focuses on the observed symptoms.

• Anti-convulsants are used to treat seizure.

• Other symptoms such glaucomamay be treated with drugs.
• Surgical procedure may be needed for re-occuring episodes of seizure and glaucoma.

• Low dosage of aspirin are sometimes administered to reduce chances of stroke.
• Laser therapy may be used to lighten or erase the port wine birthmark.

1. Thomas-Sohl KA, Vaslow DF, Maria BL. Sturge-Weber syndrome: a review. Pediatr Neurol. 2004; 30(5):303-10.

2. AuShirley M, Tang H, Gallione C, et al. Sturge-Weber syndrome and port-wine stains caused by somatic mutation in GNAQ. N Engl J Med. 2013; 368(21):1971.

3. Comi AM. Advances in Sturge-Weber syndrome. Curr Opin Neurol. 2006; 19(2):124-8.
4. Comi AM. Pathophysiology of Sturge-Weber syndrome. J Child Neurol. 2003; 18(8):509-16.
5. Aylett SE, Neville BG, Cross JH. Sturge-Weber syndrome: cerebral haemodynamics during seizure activity. Dev Med Child Neurol. 1999; 41(7):480-5.
6. Okudaira Y, Arai H, Sato K. Hemodynamic compromise as a factor in clinical progression of Sturge- Weber syndrome. Childs Nerv Syst. 1997; 13(4):214-9.
7. Reid DE, Maria BL, Drane WE. Central nervous system perfusion and metabolism abnormalities in Sturge- Weber syndrome. J Child Neurol. 1997; 12(3):218-22.
8. Maria BL, Neufeld JA, Rosainz LC. Central nervous system structure and function in Sturge-Weber syndrome: evidence of neurologic and radiologic progression. J Child Neurol. 1998; 13(12):606-18.
9. Sujansky E, Conradi S. Outcome of Sturge-Weber syndrome in 52 adults. Am J Med Genet. 1995; 57:35-45.
10. Comi AM. Presentation, diagnosis, pathophysiology, and treatment of the neurological features of Sturge-Weber syndrome. Neurologist 2011; 17:179.
11. Maria BL, Hoang KBN, Robertson RL, et al. Imaging brain structure and function in Sturge-Weber Syndrome. In: Bodensteiner JB, Roach ES, eds. Sturge-Weber Syndrome. Sturge Weber Foundation. Mt Freedom, New Jersey. Sturge Weber Syndrome. 1999; 43-69.
12. Debicka A, Adamczak P. Przypadek dziedziczenia zespolu Sturge'a-Webera. Klin Oczna. 1979; 81:541-542.
13. Bruce DA. Neurosurgical aspects of Sturge-Weber syndrome. Bodensteiner JB, Roach ES, eds. Sturge-Weber Syndrome. Mt Freedom, NJ: Sturge Weber Foundation. 1999; 39-42.
14. Patrianakos TD, Nagao K, Walton DS. Surgical management of glaucoma with the sturge weber syndrome. Int Ophthalmol Clin. 2008; 48(2):63-78.