Colour vision defects in asymptomatic carriers of the Leber's hereditary optic neuropathy (LHON) mtDNA 11778 mutation from a large Brazilian LHON pedigree: a case-control study

AIMS

To determine if asymptomatic carriers from a previously identified large pedigree of the Leber's hereditary optic neuropathy (LHON) 11778 mtDNA mutation have colour vision deficits.

METHODS

As part of a comprehensive analysis of over 200 members of a large Brazilian LHON pedigree spanning seven generations, colour vision tests were obtained from 91 members. Colour vision was tested one eye at a time using the Farnsworth-Munsell 100 (FM-100) hue colour vision test. The test was administered under uniform conditions, taking into account: ambient light levels, daylight colour temperature of 6700 kelvin, and neutral uniform background. Tests were scored using the FM-100 MS-Excel computer scoring program. Defects were determined and categorised as tritan, deutan, or protan. Categorisation of each dyschromatopsia was based on review of demonstrated axis computer generated plots and age adjusted error scores which coincided with Verriest 95% confidence intervals. Only the axis with the greatest magnitude error score was used to classify the defect. 55 of the 91 test subjects were LHON mtDNA 11778 J haplotype mutation carriers, proved by mtDNA analysis. The remaining 36 subjects were age matched non-blood relatives (off pedigree), who served as controls.

RESULTS

27 of 55 carriers (49.10%) were shown to have colour vision defects in one or both eyes. 13 of the 27 (48%) abnormal tests in the carrier group were tritan defects and the remaining 14 (52%) were deutan defects. Nine of the 27 (33%) abnormals in the carrier group were identified as having bilateral defects. Six of these were deutan, and the remaining three were tritan dyschromatopsias. Only six of the 36 (16.66%) age matched controls were found to have any type of dyschromatopsia. Five (83.3%) of these were deutan defects. The remaining one was a tritan defect. The difference between the two groups using a chi(2) test with one degree of freedom was statistically significant with a p value less that 0.001.

CONCLUSIONS

Until now, LHON has always been characterised by a sudden, devastating vision loss. Asymptomatic carriers, those without vision loss, were considered unaffected by the disease. It now appears that asymptomatic carriers of the LHON mutation are affected by colour vision defects and may manifest other subtle, yet chronic, changes.

Occurrence of familial nonarteritic anterior ischemic optic neuropathy in a case series

OBJECTIVE

To report on the occurrence of familial nonarteritic anterior ischemic optic neuropathy (NAION) in our NAION series.

METHODS

One hundred forty-eight consecutive retrievable cases of NAION were surveyed regarding the occurrence of NAION in other family members. Medical records of affected family members were reviewed, and clinical characteristics of documented familial NAION cases were described.

RESULTS

Of 79 patients who returned the survey, four reported one or more relatives with previously diagnosed NAION. There were nine cases of documented NAION in these four families. All cases occurred in siblings, with a mean age at onset of 55 years. Six patients had second eye involvement and in five, involvement became bilateral within 4 years after initial onset. None of the patients had diabetes; two had hypertension.

CONCLUSION

A small number of patients with NAION may belong to a familial subclass. Three previous reports of familial NAION further support this hypothesis.

Bilateral trochlear nerve palsy associated with cryptococcal meningitis in human immunodeficiency virus infection

This is the report of a case of bilateral trochlear nerve palsy secondary to cryptococcal meningitis in a 34-year-old woman with acquired immune deficiency syndrome. Based on clinical and neuroradiologic findings, it is concluded that in the present case, a postinflammatory shrinking of the arachnoid has stretched the fourth cranial nerves at their point of emergence from the dorsal surface of the brainstem.

Indocyanine green angiography in enlarged blind spot syndrome

PURPOSE

To report the indocyanine green angiography findings in a case of acute idiopathic blind spot enlargement syndrome.

METHOD

The patient underwent ophthalmologic examination with fluorescein angiography and indocyanine green angiography.

RESULTS

A monocular enlarged blind spot was found on automated perimetry; fluorescein angiography showed a hypofluorescent peripapillary atrophic area and indocyanine green angiography highlighted diffuse, small hypofluorescent spots scattered throughout the posterior pole. Visual field defects and indocyanine green angiography abnormalities resolved over 4 weeks.

CONCLUSION

Indocyanine green angiography in acute idiopathic blind spot enlargement syndrome showed many lesions not visible with fluorescein angiography, indicating a choroidal involvement reaching not only the peripapillary area but the entire posterior pole.

Childhood Leber's hereditary optic neuropathy (ND1/3460) with visual recovery

The authors report the clinical features and the results of genetic and biochemical studies of a child affected by ND1/3460 Leber's hereditary optic neuropathy, who demonstrates a persistent visual recovery after protracted monitoring. A 10-year-old male suffered from a severe right visual impairment that was incidentally detected. Within 2 months the left eye was also seriously involved, and visual acuity worsened to 20/300 in both eyes, associated with bilateral cecocentral scotomas and dyschromatopsia. During the following months a progressive visual improvement occurred, and 2 years later the visual acuity was 20/20 OU. After 9 years of follow-up the clinical status is unchanged. The mutation at np ND1/3460 was found to be virtually homoplasmic in the proband's mtDNA, which was extracted either from platelets or leukocytes, whereas the mother and the sister tested heteroplasmic for the same mutation. The specific activity of complex I in platelets was reduced in the proband and normal in his relatives. An abnormal resistance of NADH:ubiquinone reductase to the inhibitory effect of rotenone was found in platelet mitochondria from the proband and family members and was consistent with the degree of heteroplasmy. This pattern of biochemical abnormalities suggests a cumulative effect of the increasing percentage of mutated mtDNA on complex I function, which involves the interaction between complex I and its substrate ubiquinone in the heteroplasmic condition (asymptomatic state), and the catalytic function of complex I, as mutated mDNA turns toward the homoplasmic condition (symptomatic state).

Septic cavernous sinus thrombosis following transsphenoidal craniotomy. Case report

The authors present a case of late-onset cavernous sinus thrombosis in a 74-year-old man who had undergone transsphenoidal craniotomy for a pituitary macroadenoma 9 weeks previously. The patient developed headache, rapidly progressive ophthalmoplegia, and signs of orbital congestion. After 2 days of ineffective broad spectrum antibiotic therapy he underwent a second transsphenoidal craniotomy for abscess drainage. Intraoperative cultures grew 4+ non-hemolytic Streptococcus, 4+ Staphylococcus coagulase negative, and 4+ Haemophilus influenzae. The patient was maintained on intravenous antibiotic therapy for the following 6 weeks, resulting in a complete clinical recovery. To the authors' knowledge, this is the first report of a septic cavernous sinus thrombosis following a transsphenoidal craniotomy.

Rapid growth of an optic nerve ganglioglioma in a patient with neurofibromatosis 1

BACKGROUND

Optic nerve gangliogliomas are extremely rate tumors of the central nervous system composed of elements of glial and neuronal origin. The clinical and biologic behavior of gangliogliomas depends on the glial component. Pilocytic gangliogliomas generally have a low growth rate and good ultimate prognosis. No definitive relation has yet been established between gangliogliomas and neurofibromatosis type 1.

METHODS

The authors describe the clinical, histologic, and immunohistochemical features of an optic nerve ganglioglioma with several atypical findings. A review of the literature is provided.

RESULTS

An optic nerve glioma was diagnosed in a 16-year-old patient who had signs of neurofibromatosis type 1; the atypical clinical course involved a rapid progression of symptoms with a significant increase in tumor size. The tumor was removed surgically and found to be a ganglioglioma composed of pilocytic glial cells (immunoperoxidase-positive for glial fibrillary acid protein) and neurons (immunoperoxidase-positive for neuron specific enolase, synaptophysin, and neurofilament). A focal astrocytic area showed increased cellularity, several mitotic figures, and an elevated labeling index with Ki-67 immunoperoxidase staining.

CONCLUSION

Optic nerve gangliogliomas are rare tumors that cannot be distinguished clinically from pilocytic astrocytomas. Although these tumors usually grow slowly, careful follow-up is advised. The atypical histologic features are considered to be a manifestation of rapid local growth rather than a harbinger of malignant behavior. The authors' findings suggest that gangliogliomas may be included in the diagnostic criteria for neurofibromatosis type 1.