Kembara Xtra - Medicine - Temporal Arteritis

Kembara Xtra - Medicine - Temporal Arteritis 
​ESSENTIAL DESCRIPTION

Giant cell arteritis (GCA), as it is officially known, is a chronic, systemic, cellular, and humoral immunemediated vasculitis of large and medium-sized vessels that mostly affects the cranial arteries that originate from the aortic arch, though vascular involvement may be broad. In 50% of instances, the aorta is found to be inflamed. Aortic arch syndrome (decreased or absent peripheral pulses, differences in blood pressure, arterial bruits), polymyalgia rheumatica (PMR) symptoms, weariness, headaches, jaw claudication, ocular complaints, scalp discomfort, and PMR symptoms are common signs.
Ophthalmic artery occlusion is a medical emergency because it poses a danger of permanent vision loss if it is not treated.

The most prevalent type of systemic vasculitis that affects people under 50 is epidemiology.
The age range for 80% of cases is 70 to 80.
When it comes to those of Northern European heritage, women are impacted around two to three times more than men.
The most prevalent vasculitis in people with a Northern European ancestry
Very uncommon among people of Asian or African descent
Lower BMI is linked to a higher risk Incidence Ethnicity-specific incidence.
There are 2 cases per 1,000 people in Northern Europeans.
Peaks in patients between the ages of 70 and 80

PATHOPHYSIOLOGY AND ETIOLOGY
Although current research implies that advanced age, ethnicity, and particular genetic susceptibility lead to a maladaptive response to endothelial damage, intimal hyperplasia, and ultimately vascular stenosis, the precise etiology of GCA is unknown.
● The elastic lamina of medium- and large-sized arteries are most impacted by the chronic, systemic vasculitis known as GCA.
The intima, media, and adventitia of the afflicted arteries exhibit transmural inflammation, and there is also patchy infiltration of lymphocytes, macrophages, and multinucleated giant cells. Mural hyperplasia may cause a narrowing of the artery lumen, which will then cause distal ischemia.
● According to current thinking, the pathogenesis of GCA results from an improper activation of T-cell-mediated immunity by immature antigen-presenting cells following a maladaptive response to endothelial injury. Following this, the arterial vessel wall may produce cytokines that may draw macrophages and multinucleated giant cells, which create granulomatous infiltrates and give sick vessels their distinctive histology. Additionally, this causes T lymphocytes that are directed towards antigens in or near the elastic lamina to oligoclonally expand. In the end, this cascade causes stenotic occlusion, intimal hyperplasia, and damage to the vessel wall.
The relationship between GCA and PMR has been widely recognized in recent years.
● Varicella zoster virus has been suggested as a potential immunological trigger for GCA, however this has not been proven, and supplementary antiviral therapy is still debatable.
Genetics Polymorphisms in the HLA-DRB1*04 gene, ICAM-1, and PTPN-22 have all been linked to an increased chance of developing GCA.

RISK FACTORS The biggest risk factor is getting older (>70 years).
• Women

 Genetic predisposition—reported familial grouping on occasion.
Smoking history; early menopause (43 years); reduced BMI at menopause in women aged 50 to 69; environmental factors that affect vulnerability;


CONDITIONS OFTEN Associated with
Population studies have revealed that 16–21% of patients with PMR also have GCA, and 40–60% of patients with GCA also have PMR symptoms.

DIAGNOSIS HISTORY
The majority of patients' most frequent presenting symptom is headache.
Any visual problems (amaurosis fugax, diplopia) Constitutional symptoms (fever, exhaustion, weight loss) Vision loss (20% of patients); unilateral is most common, frequently progresses to bilateral if managed.

Claudication of the upper extremities or tongue; Scalp tenderness or sensitivity; PMR symptoms (shoulder and hip girdle pain and stiffness); Distal extremity swelling/edema; Claudication of the jaw (presence of symptom greatly increases likelihood of a positive biopsy);
Upper respiratory conditions

Temporal artery anomalies (beading, prominence, soreness) on physical examination typically appear "ill"
Lower peripheral pulses when major vessel disorders are present
Funduscopic examination reveals scattered cotton wool patches, tiny hemorrhages, and pale and edematous optic discs, in contrast to other kinds of vasculitis that frequently affect the skin, kidneys, and lungs.
Bumps above the eyes, axilla, and supraclavicular


Migraines, herpes zoster, other vasculitis (Takayasu arteritis, Wegener, PAN), and other rheumatologic conditions (RA, PMR, MCTD) are among the differential diagnoses.

DETECTION & INTERPRETATION OF DIAGNOSIS

The following are the American College of Rheumatology's 1990 classification standards:
>50 years old
- A recent, little headache
- Temporal artery abnormalities, including palpable discomfort and weak or absent pulses
abnormal temporal artery biopsy demonstrating vasculitis with predominance of mononuclear cell infiltration or granulomatous inflammation
ACR criteria that meet three or more of the requirements show a sensitivity of 94.5% and a specificity of 91.2%.
Initial examinations (lab, imaging)
Although nonspecific (27%), ESR >50 mm/hr (86% sensitivity); occasionally, may be normal
A positive biopsy result is more likely when the C-reactive protein (CRP) level is greater than 2.45 mg/dL (97% sensitivity).
The diagnosis of GCA is doubtful if the ESR and/or CRP are normal.
Acute-phase reactants, such as fibrinogen and interleukin-6, are frequently increased but extremely nonspecific and only used in cases that are challenging to diagnose.
Mild anemia is relatively vague but may be linked to a lower incidence of ischemia consequences.
Color Doppler US of the temporal artery can detect arterial occlusion, stenosis, or edema (the "halo sign"); nonetheless, it is inexpensive, noninvasive, and highly operator dependent, and it does not appreciably enhance the clinical exam. It might support the diagnosis of involvement of bigger vessels.
If the carotid intima-media thickness is greater than 0.9 mm, atherosclerotic disease may mimic the halo sign.
If done within 5 days after steroids, MRI and MRA may aid in diagnosis (78% sensitive, 90% specific).
Positron emission tomography (PET), MRI/MRA, and color Doppler may be helpful in diagnostically challenging cases to quantify the inflammatory burden and early in the course of disease because the metabolic changes occur prior to structural vascular damage, but there aren't any studies to back up their use.

Tests in the Future & Special Considerations
Aortic dissection can result from the development of aortic aneurysms, a late and potentially fatal consequence of GCA.
Prior to doing the temporal biopsy, treatment with high-dose steroids should be initiated when there is a strong clinical suspicion of GCA due to the possibility of irreparable vision loss.

Other/Diagnostic Procedures
The gold standard diagnostic test is a histopathologic analysis of the temporal artery biopsy samples. If there is any reason for concern, begin treatment right once because pathology may persist for up to 14 days after starting steroid therapy.
Sensitivity is 87% overall.
The temporal artery was chosen because it is easily accessible in patients with systemic diseases; however, other cranial arteries or the facial artery may also be used.
Because skip lesions can occur, the length of the biopsy material should be at least 2 cm to prevent false-negative results.
If a biopsy is combined with imaging (high-resolution MRI or color Doppler US), the diagnostic yield may be improved.
It is not recommended to do a bilateral temporal artery biopsy unless the initial histology is negative and the suspicion for GCA is still strong.
Can be negative in up to 42% of GCA patients, especially in big vessel disease, and should not be used to guide treatment decisions.
Prior glucocorticoids had little impact on the results of a biopsy, thus treatment shouldn't be postponed.

Test interpretation: Fragmentation and disruption of the internal elastic lamina, together with inflammation of the arterial wall
Although they are not unique to the illness, multinucleated giant cells are discovered in about 50% of cases.
Three histologic patterns of GCA exist: classic, atypical, and healed.

TREATMENT /MEDICATION

First-Line Glucocorticoids: Prednisone is often used in doses of 60 to 80 mg per day (or 1 mg per kilogram), with the amount being adjusted as necessary to treat symptoms. Alternate day therapy with steroids is not recommended since it increases the risk of a vasculitis relapse.
If vision loss has been noticed, IV steroids are advised; otherwise, PO steroids are just as effective.
Prior to biopsy confirmation, urgent steroid medication should be started given the potential of irreparable vision loss.
The first dose of steroids is sustained for two to four weeks before being gradually decreased over a period of nine to twelve months. Tapering might take two years or less (1)[A]. While on taper, keep an eye on your symptoms, ESR, and CRP to check for relapse.
Although tocilizumab (an IL-6 receptor antagonist) comes with a black box warning about an increased risk of opportunistic infections, it may be better than prednisone alone in some cases.
Low-dose aspirin has been proposed as a treatment option for GCA patients.
Next Line
In addition to glucocorticoid therapy, methotrexate may have a negligible impact on GCA relapse rates.
Cyclophosphamide has showed some promise in treating patients who did not respond well to glucocorticoids.
Additionally, glucocorticoids may be used in conjunction with azathioprine and abatacept.
Therapies that target TNF as an addition to steroids have not demonstrated a meaningful benefit.

CONTINUING CARE AFTERCARE RECOMMENDATIONS

Avoiding the sun and shielding the face and head from photodamage may later show to be crucial GCA prevention strategies.
patient observation
GCA normally lasts a few months to many years and is self-limited.
GCA does not appear to shorten lifespan generally.
However, it could result in severe problems like sight loss, which happens in roughly 15-20% of individuals.
The formation of aortic aneurysms, which often affect the ascending aorta, is another side effect of GCA. Chest x-rays taken once a year might help to detect this issue.
PMR (stiffness of the shoulder and hip girdle) will eventually develop in about 50% of GCA patients.
As recommended by atherosclerosis recommendations, low-dose aspirin should be administered.
DIET
Supplemental calcium and vitamin D should be given to avoid osteoporosis caused by long-term corticosteroid medication.

PATIENT EDUCATION Effects of suddenly stopping steroid use (adrenal insufficiency, recurrence of illness)
Long-term steroid use risks, including infection, high blood sugar, weight gain, slowed wound healing, osteoporosis, and hypertension
The potential for relapse and the significance of notifying the provider right once of any fresh headaches and changes in vision

PROGNOSIS: The illness might range in duration from a year to a chronic course.

Unless there is severe aortitis present, the condition has no effect on life expectancy.
In most people, glucocorticoid therapy can eventually be stopped without consequences in the majority of patients, but once vision loss has occurred, it is unlikely to be regained. However, treatment addresses the other symptoms and prevents further vision loss and stroke. On the other hand, prednisone may need to be taken for years in people with chronic illnesses.
Relapses in the illness are possible.

COMPLICATIONS include vision loss from a delayed diagnosis and toxicity from glucocorticoids.