Bilateral Optic Atrophy with Thickened Meninges ( Idiopathic Hypertrophic Pachymeningitis )-A Rare Entity

Journal of Medical Sciences 2011;14(1):25-27


Discussion
The etiology of Hypertrophic chronic pachymeningitis (HCP) is unclear, although several causative factors have been recognized,including infections, autoimmune disorders, and 1, 2 neoplasms.However, most cases, with no evident etiology 3 are classified as Idiopathic Hypertrophic Pachymeningitis.as was the case with our patient.It has a non-specific clinical picture comprising headache, vomiting, cranial nerve palsy, ataxia, raised intracranial pressure and focal neurological defecit.Masson et al. found that headache was invariably present but did not show any specific pattern, except when 3 there was hydrocephalus.They also found ophthalmoplegia to be common with frequent dysfunction of optic nerve.Other symptoms include hypoacusis, tinnitus, dizziness, trigeminal neuralgia, and dysphagia.Tolosa Hunt syndrome may be a focal manifestation of hypertrophic pachymeningitis, since they 4 share common pathological features.Anatomical aspects of the cavernous sinus make it more frequently affected than 3 fluid (CSF) analysis revealed 7 lymphocytes/mm, proteins of 29 mg/dl and sugar of 81 mg/dl.Microbiological evaluation of the CSF for cryptococcal antigen, VDRL, and cultures for acid fast bacilli (AFB) and fungi yielded no positive results.Contrast MRI brain revealed diffuse meningeal enhancement compatible with hypertrophic pachymeningitis (Fig. 1) Right parieto-occipital craniotomy was done, which revealed thickened, grey and grossly fibrotic dura matter.A biopsy was obtained from the right parietal dura mater.Histopathological examination of the meningeal biopsy revealed a dense fibrous tissue infiltrated with lymphocytes and polymorphs.There was no granuloma formation or vasculitis.Specific stains for fungi and acid fast bacilli were negative.(Fig.2) Cultures of dura were negative as were serological and PCR tests.
Patient was put on steroids and Azathioprine and within 3 weeks her symptoms improved.Presently patient is on our follow up.The CSF findings are dependent on the etiology.In Idiopathic cases, CSF frequently shows non-specific 3 pleocytosis, rarely over 100 cells/mm, predominantly lymphocytic.There can be an increase in protein content with 4 rise of immunoglobulins and elevation of IgG index.MRI is a useful radiological method in evaluating a patient with suspected thickening of meninges.In early stage of the disease, peripheral enhancement and T2 hyperintensity are common and correspond to inflammatory activity while hypointensity is attributed to fibrosis.The use of gadolinium may differentiate between pachy-and leptomeningitis MRI also demonstrates areas suitable for biopsy and secondary lesions that may 6, 7 accompany the disease.
Histopathological findings are that of an inflammatory process with lymphomononuclear cell infilitration and a thickened dura mater characterized by a dense hypocellular 8 fibrous tissue.Specific patterns such as necrotizing vasculitis and noncaseous epithelioid granulomas can be found depending on the etiology.
The diagnosis of IHP should be made with due precaution especially in developing countries where these infections are common.In recent literature there is no consensus on the adequate management of IHCP.Spontaneous resolution of both clinical symptoms and signs, and dural thickening has 9 been reported.A variety of therapeutic approaches have been tried alone or in combination.Corticosteroid therapy is often effective in ameliorating the symptoms and signs, and in 10 stopping the disease progression.Attempts should be made to exclude other underlying conditions before prescribing corticosteroid or other immunosupressants.Methotrexate can be effective and a therapeutical option in patients with IHCP who are resistant to corticosteroids or present major side-11 effects of chronic corticosteroids use.
In patients with marked pleocytosis, intraventricular cytarabine has been tried with success to stop meningoproliferative process.Surgical excision is sometimes necessary for patients with mass effect due to thickening of the skull

4 , 5 other
dural sinuses.The signs and symptoms in IHP are due to entrapment of cranial nerves, occlusion of CSF flow, venous sinuses and rarely arteries.