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Peripheral nerve involvement—mononeuritis,1 mononeuritis multiplex, and polyneuropathies2—has been reported in 14% of patients with giant cell arteritis (GCA).3 4 GCA associated with acute inflammatory demyelinating polyneuropathy (AIDP) has exceptionally been described.5 6 We report an unusual case of this association.
A 67 year old woman presented with a one month history of difficulty in walking, weakness, and proximal myalgia that worsened progressively. Examination showed proximal weakness and abolition of all deep tendon reflexes; there was no sensory deficit and cranial nerve function was normal. Laboratory tests disclosed normal haematological findings with an erythrocyte sedimentation rate (ESR) of 12 mm/1st h; renal and liver function tests, muscle enzymes, and thyroid stimulating hormone were in the normal range. Serum protein electrophoresis, antinuclear antibodies and rheumatoid factors, and serology for Lyme disease, Q fever, mycoplasma, Venereal Disease Research Laboratory test, HIV, and cytomegalovirus were all negative. Chest radiographs and abdominal echography were normal. Electrophysiological investigation disclosed an inflammatory demyelinating polyradiculoneuropathy, with prominence of motor and proximal involvement. The cerebrospinal fluid (CSF) showed four mononuclear cells/ml; protein 0.56 g/l and glucose 3.4 mmol/l.
At this moment, an AIDP or Guillain-Barré syndrome was diagnosed, and plasma exchange was performed, using standard procedures. After the second plasma exchange, the weakness had completely disappeared, but the patient started with fever (40°C) and increasing bitemporal and occipital headache. Physical examination showed that temporal and occipital arteries were nodular and swollen with palpable pulse. Laboratory tests disclosed haemoglobin 78 g/l, platelet count 999×109/l, ESR 94 mm/1st h, alkaline phosphatase 170 U/l, and γ-glutamyltransferase 99 U/l. Temporal artery biopsy disclosed changes typical of GCA. Treatment with prednisone orally 1 mg/kg weight was started. There was an excellent response, the symptoms stopped within days and the ESR and liver function test returned to normal. Prednisone was reduced gradually over time. Repeated nerve conduction studies showed an objective improvement.
Ten months later, when she was taking prednisone 10 mg/day, the proximal weakness started again, worsening over the following weeks. Electrophysiological study showed progression of the demyelinating polyradiculoneuropathy. She had no other symptoms. Haematological and blood chemical findings were all normal, as was the ESR. Plasma exchange sessions were restarted. The diagnosis at this time was an AIDP relapsing form. Prednisone was given at 1 mg/kg weight. She improved rapidly. Because of the serious side effects she had previously had with the steroid treatment (30 kg weight gain, hyperglycaemia, mental changes) and the poor vascular access she had for the plasma exchange, we decided to start treatment with intravenous immunoglobulin pulses, 0.4 g/ kg weight every four weeks. Steroids were tapered and the patient remained clinically well during the following year.
To our knowledge, only two cases of GCA associated with AIDP have been previously reported (table 1), and no association of GCA with the AIDP relapsing form has been previously described. The first case refers to a patient who presented a clinical picture of AIDP and in whom temporal arteritis was diagnosed two weeks later.5 In the second case the patient was diagnosed as temporal arteritis,6with a compatible biopsy; he was treated with prednisone and four weeks later he presented a generalised weakness: CSF and electrophysiological study were concordant with AIDP. A sural nerve biopsy was not done in these cases.
The neuropathies associated with temporal arteritis and other vasculitis have been attributed to ischaemic lesions of the nerves due to an arteritis of the vasa nervorum. A vasculitic neuropathy was excluded in our case because the clinical course and the electrophysiological study were characteristic of AIDP.
The underlying cause and pathogenic mechanisms of AIDP and GCA are not well understood. Immune cellular mechanisms have an important role: an increasing number of T CD4+ cells and macrophages in demyelinated regions of the nerve are seen in AIDP7; the histopathology of GCA shows a mixed inflammatory infiltrate with T CD4+ lymphocytes and macrophages secreting proinflammatory cytokines.8
Temporal arteritis associated with inflammatory demyelinating polyradiculoneuropathy may be a coincidence, but a common inmunological pathogenesis, probably based on a cellular T cell dependent mechanism and related to a cytokine deregulation, cannot be ruled out. Infectious agents, such as a virus, may be the cause of the onset of both diseases in a subset of patients.7 9
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