Quantitative analysis of optic nerve damage in idiopathic intracranial hypertension (IIH) at diagnosis.

Optic neuropathy secondary to idiopathic intracranial hypertension (IIH) may be a severe complication which must be early identified, adequately monitored and treated to avoid blindness. The aim of this study was to quantify optic nerve involvement at time of diagnosis in a prospectively series of IIH investigated at a single Institution and to identify objective parameters for early diagnosis and follow-up. 38 consecutive patients (9 men, 29 females, mean age 39.8 years) with IIH underwent a complete neuro-ophthalmological evaluation including standardized automated perimetry as functional measurement of optic neuropathy and spectral domain optical coherence tomography (SD-OCT) measurements to grade papilledema or optic nerve atrophy. An overall diagnosis of optic nerve involvement was made in 50 out of 76 eyes (66 %); ophthalmoscopic signs of papilledema were identified in 35 eyes (46 %) while optic disc pallor was found in 13 (17 %). In all patients mean visual field deviation (MD, dB) was -7.2 (range 5.3-33.2). SD-OCT measurements of peripapillary retinal nerve fiber layer thickness (PRNFLT) and of macular ganglion cell complex thickness (MGCCT) obtained in 40 eyes (20 subjects) showed normal PRNFLT in 12 eyes (30 %), increased in 16 (40 %) and reduced in 12 eyes (30 %); normal MGCCT in 26 eyes (65 %), reduced in 14 (35 %). In all eyes average RNFLT was increased (mean 130 µm, range 219-59) and average MGCCT was decreased compared to normal values (mean 89.5 µm, range 198-65). Increased PRNFLT was associated with reduced MGCCT in 4 eyes (10 %) indicating early retrograde optic nerve damage. Decreased PRNFLT was associated with decreased MGCCT in 10 eyes (83 %). These results indicate that, in IIH patients, signs of optic neuropathy can be identified in more than half of cases, even without papilledema evidenced on ophthalmoscopic examination. Moreover, an SD-OCT analysis, which can be definitively useful to quantify optic nerve edema or atrophy, can show damage of retinal ganglion cells in an early phase of the disease.

Headache prevalence and clinical features in patients with idiopathic intracranial hypertension (IIH).

Headache is a key symptom of idiopathic intracranial hypertension (IIH). Operational diagnostic criteria for "Headache attributed to IIH" are included in the international classification of headache disorders, the ICHD-2. The association of IIH with obesity was established by several reports. We investigate the prevalence of headache and its main clinical features in a clinical sample of IIH patients. The possible correlations between the presence of headache and body mass index (BMI) and intracranial pressure (ICP) levels were studied in a consecutive clinical series of patients, in whom diagnosis of IIH was confirmed by exclusion of secondary forms and by the evidence of increased ICP. Differences for age, BMI, and ICP between patients with and without headache and between males and females were assessed with Mann-Whitney U test. Spearman's correlation analysis was used to assess relationships between age, BMI, and ICP. P value < 0.05 was used to set statistical significance. 40 patients entered the study (9 males, 31 females; mean age 39, 8 years, SD 13.2). Headache was reported by 75 % patients. Those characteristics which are included in the present international diagnostic criteria for "Headache attributed to IIH" were reported by a remarkable proportion of the studied patients, but not by all. On the other hand, some headache features usually attributed to migraine forms, and which are not among the required criteria were present in some patients: pulsating quality and unilateral distribution of pain in around 20 %, and migrainous associated symptoms in more than 40 % of the sample. According to statistical analyses, no differences were found for age, BMI, and ICP between patients with and without headache. Our results confirmed the strong association between headache and IIH. Although no significant correlations between some of the key features of IIH were found in this study, we suggest that further studies on larger series--possibly with a longitudinal evaluation--are needed, to help clinicians in categorizing different subgroups among IIH patients as well as in identifying the main factors influencing the prognosis of this disorder.

A longitudinal conventional and magnetization transfer magnetic resonance imaging study of optic neuritis.

Eleven consecutive patients with a first episode of acute optic neuritis were evaluated, using conventional and magnetization transfer (MT) magnetic resonance imaging (MRI), in order to assess the temporal evolution of optic nerve (ON) damage and to investigate the correlation of ON damage with visual outcome and electrophysiological parameters. Patients underwent neuroophthalmological, neurological, electrophysiological, and MRI assessments at baseline and after three and 12 months. ON volumes were measured on coronal T1-weighted images using a local thresholding segmentation technique. MT ratio (MTR) from the ON was derived from gradient echo images. No significant volume difference was detected between affected and healthy ON, both at baseline and follow-up. At baseline, mean MTR values were significantly higher in affected ON than in healthy ON (P =0.001), whereas at months 3 and 12, the mean MTR values were significantly reduced in the affected ON (P =0.02 and 0.003, respectively). Mean MTR of the affected ON, corrected for healthy ON values, progressively decreased over time (P =0.04 at month 3 and P =0.0012 at month 12). On the contrary, MTR values of healthy ON remained stable. No correlations were found between MTR measures and clinical or electrophysiological data. This study shows the presence of subtle pathological changes, possibly due to residual demyelination and subsequent additional demyelination and impaired remyelination, in the ON of patients with a first episode of optic neuritis. In the early phase of optic neuritis, MT MRI is more sensitive than atrophy measurements in detecting disease-related changes.