CONTRIBUTION OF IMAGING IN CHRONIC MENINGITIS A. BEN MILED, F. JABNOUN, M. BEN ALI, K. BOUZAIDI, I. KECHAOU, A. KHELIL NEURORADIOLOGY : NR 21

INTRODUCTION The contribution of slice imaging in the chronic meningitis diagnosis process is considerable allowing often a confirmation of the positive diagnosis, and an etiological orientation. Exclusion of abscess tumors and para meningeal focus of infection in cranial sinusis or paravertebral location are important objectives of imaging in the setting of chronic meningitis. Most patients with a chronic meningitis, however will have normal imaging or non specific findings.

SUBJECTS AND METHODS A retrospective study of 7 patient observations comprising of 3 men and 4 women with a mean age of 43 years. Investigated by CT scan and/or MRI for headaches associated with polyuro-polydipsia syndrome (3 cases), convulsions (2 cases) and headaches with fever (2 cases). In this presentation, we are illustrating the different CT scan and MRI aspects of these chronic meningitis.

RESULTS The radiological explorations involving CT scan and MRI show and conclude to: Metastatic leptomeningitis (3) Neuro sarcoidosis (2) Idiopathic hypertrophic pachymeningitis (1) Langerhans Cell histiocystosis (1)

CHRONIC MENIGITIS SYMPTOMS Pleomorphic clinical manifestations encompassing symptoms and signs in 3 domains of neurologic function: The cerebral hemispheres: Headache, decrease in mental abilities, confusion. The cranial nerves: loss of feeling in the face, diplopia, trigeminal sensory or motor loss, cochlear dysfunction, and optic neuropathy. The spinal cord and roots: disturbances in the ability use the legs and arms, back pain, weakness, burning or prickling sensations.

CHRONIC MENIGITIS IMAGING FINDINGS MRI have a higher sensitivity than CT Better contrast resolution Avoid the artefact beneath the inner table that limits the visualization of meningeal enhancement with CT. Imaging should be obtained preferably prior to the lumbar puncture which may cause a meningeal reaction

CHRONIC MENIGITIS IMAGING FINDINGS MRI CT scan can be sufficient evidencing: Hyper dense aspect of leptomeningis Important enhancement, sometimes diffuse in others nodular.

CHRONIC MENIGITIS IMAGING FINDINGS MRI Leptomeninges thikening and enhancement: Fine signal-intense layer that follows the gyri , superficial sulci, ependymal lining and perivascular spaces (appearance of intraparenchymal lesion) Cranial nerve enhancement in the subarachnoid cisterns. Enhancing dural based mass. Intradural extramedullary enhancing nodules on spinal MR

IMAGING FINDINGS CHRONIC MENIGITIS MRI Hydrocephalus: may the first and only sign of leptomeningeal spread of disease. Axial T2 image shows hydrocephalus with transependymal seepage of CSF.

CHRONIC MENIGITIS IMAGING FINDINGS MRI FLAIR images may depict evidence of leptomeningeal lesion: An hyperintensity in the subarachnoid space resulting from elevations in CSF cellularity and protein concentrations.) FLAIR MR image shows extensive sulcal hyperintensity.

CHRONIC MENIGITIS Imaging signs of leptomeningeal damage are common regardless of the etiology Etiologic diagnosis is guided by: The clinical and biological context A particular distribution of leptomeningeal damage Other brain locations non leptomeningeal Other non cerebral locations

Case n° 1 40 year old woman. Antecedent of operated breast cancer. Consulting for seizures. Axial without and with contrast CT images showing widespread leptomeningeal enhancement involving surfaces of cerebellum hemispheres in connection with metastatic origin. Subarachnoid enhancement over cerebral surfaces and contrast gain in mass of the falx cerbri.

Case n° 2 62 year old men. Antecedent of lung cancer. Convulsions. Axial enhanced CT images showing diffuse linear and nodular meningeal enhancement.

Metastatic leptomeningitis Leptomeningeal carcinoma, is a form of metastatic cancer that has spread to the lining of the brain and spinal cord. The most meningeal metastasing cancers: leukemia, lymphoma, melanoma, breast, lung and gastrointestinal cancers. Carcinomas of unknown primary constitute 1% to 7% of all cases of leptomenigeal carcinoma. Diagnosis: Detection of malignant cells in the cerebrospinal fluid.

Metastatic leptomeningitis IMAGING FINDINGS MRI Non specific Leptomeninges enhancement, Cranial nerve enhancement, enhancing dural based mass. The leptomeninges of spinal cord damage is most frequently seen in the cauda equina.

Case n° 3 33 years old women Headaches Polyuro-polydipsia syndrome Axial, sagittal and coronal Contrast-enhanced T1-weighted MR images: Diffuse and nodular leptomeninges thickening and enhancement. Reached basilar and frontal leptomeninges. Hypothalamus and pituitary lesions

. Contrast-enhanced sagittal T1-weighted image in the same patient shows enhancing lesion in spinal cord and an abnormal linear leptomeningeal enhancement

Neurosarcoidosis Sarcoidosis is an idiopathic systemic disease. Formation of non-caseating granuloma affecting all parts of the body: lungs and lymph nodes+++. Women affected more than men. Third and fourth decades. In the head and spin: The leptomeninges damage +++is specially observed in the base of the brain+++ May involve bone, dura mater, nerve roots and parenchyma, individually or in combination.

Neurosarcoidosis Symptoms depend on the site of granuloma involvement, non specific; we note specially: Facial nerve paralysis, vision loss, paresis, paresthesia, diplopia, and dysarthria… Diabetes insipidus (involvement of the hypothalamus or pituitary gland). Hydocephalus is rare.

Neurosarcoidosis IMAGING FINDINGS Leptomeningeal involvement : The most typical manifestation of central nervous system sarcoidosis (40%) Diffuse or nodular Basilar meninges +++: suggestive of diagnosis (cisterns around the base of the brain) Differential diagnosis: tuberculosis; lymphoma

Neurosarcoidosis IMAGING FINDINGS May involve: Parenchyma of the brain and spine, nerve roots, dura mater, hypothalamus and pituitary.

Case n°4 26 year old man Headache, polyuro- polydipsia syndrome, visual disturbances Coronal CT (A) and MRI (B) after injection of contrast through the facial mass. (A)Tissular lesion developed at the upper wall of the maxillary sinus with intraorbital extension. (B) Thickening of the frontal meninges enhanced with contrast. He also has a marked pituitary infiltration and a lytic lesion of the skull base. Bronchoalveolar lavage: positif CD1a .

Langerhans Cell hitiocystosis Langerhans Cell hitiocystosis (LCH) is a rare disease Systemic Idiopathic granulomatous process, composed of a particular histiocytic contingent: the Langerhans cell . More common in children. Sites of involvement: Bone :90% (skull+++), Lung, lymph nodes, Skin, Soft tissue.

Langerhans Cell hitiocystosis Sites of involvement: Bone :90% (skull+++), Lung, lymph nodes, Skin, Soft tissue. The neuroimaging of LCH is, in most of the cases non specific and it can vary depending to the location, specially on MRI. The most common CNS locations are: Hypothalamus and pituitary axis (diabetes insipidus) Cerebellum Meninges, parenchyma, pineal gland, choroid plexus are rarely included.

Case n° 5 41 year old woman Chronic headache, polyuro-polydipsia syndrome Anosmia, decrease in visual acuity. Sagittal and Frontal T2-weighted images: Duremerien thickening spreading form the frontal base of the crane up to the anterior fossa, next to the clivus in a frank hyposignal T2.

Case n° 5 Sagittal and coronal contrast-enhanced T1-weighted : Peripheral enhancement of the Dura thickening.

Idiopathic Hypertrophic Pachymeningitis Hypertrophic pachymeningitis is a clinical disorder characterized by localized or diffuse enlargement of the dura mater. The underlying and neighboring leptomeninges (pia mater, arachnoidea mater) become opaque and thickened as well. If an exhaustive work-up fails to identify the cause of the meningeal changes, a diagnosis of IHP is made. Rare disorder, affecting men more often than women Peak prevalence occurring in the 6th decade of life.

Idiopathic Hypertrophic Pachymeningitis Most common manifestations: cerebellar ataxia, seizures, and neuroophthalmic symptoms (visual field loss, complete blindness, optic neuropathy). Chronic headaches resembling chronic migraines: focal meningeal irritation or possibly to localized arachnoiditis. Cranial nerve palsies (cranial nerves IV–VIII) attributed to compression of cranial nerves at the skull base by enlarged dura mater. Increased intracranial pressure with papill edema.

Idiopathic Hypertrophic Pachymeningitis Imaging Findings Smooth or nodular dural thickening isointense or hypointense with both T1- and T2-weighted sequences (fibrosis and necrosis of the dura mater). Avid enhancement after intravenous administration of contrast material. Peripheral hyperintensity can be seen on T2-weighted images active inflammation or increased vascularity of the dura mater and underlying parenchyma).

Idiopathic Hypertrophic Pachymeningitis Complications Venous sinus thrombosis Obstructive hydrocephalus Cerebral edema Associated syndromes: Tolosa-Hunt syndrome (granulomatous inflammation of the wall of the cavernous sinus resulting in painful ophthalmoplegia). Cranial polyneuritis (especially with involvement of the 7th–12th cranial nerves), Multifocal fibrosclerosis (chronic granulomatous inflammation consisting of retroperitoneal fibrosis). Riedel thyroiditis. Sclerosing cholangitis. Pseudotumor oculi Diabetes insipidus.

CONCLUSION The contribution of slice imaging in the chronic meningitis diagnosis process is considerable Allowing often a confirmation of the positive diagnosis, and an etiological orientation. The MRI is the examination of choice, however the CT scan could be sufficient in some particular clinical contexts.