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Chorioretinitis: a potential clue to the early diagnosis of subacute sclerosing panencephalitis
  1. Vijayabala Jeevagan1,2,
  2. Athula Dissanayake1
  1. 1 Teaching Hospital Karapitiya, Galle, Sri Lanka
  2. 2 National Hospital of Neurology and Neurosurgery, London, UK
  1. Correspondence to Dr Vijayabala Jeevagan, National Hospital of Neurology and Neurosurgery, 33, Queen Square, London WC1N 3BG, UK; jeevaganv{at}yahoo.com

Abstract

We describe a 36-year-old man with subacute sclerosing panencephalitis (SSPE) presenting with chorioretinitis two years before onset of other neurological features. He had neither myoclonus nor the typical EEG features of SSPE. The diagnosis was confirmed in the appropriate clinical setting by detecting elevated measles antibody titres in cerebrospinal fluid and serum. Clinicians should consider SSPE among the differential diagnoses in chorioretinitis. This is particularly so if there is macular or perimacular involvement with concurrent involvement of the optic nerve in young patients, even without other characteristic neurological symptoms.

  • subacute sclerosing panencephalitis
  • chorioretinitis
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Background

A 36-year-old man was referred from psychiatry for evaluation of abnormal behaviour. Two weeks before, he had been wandering aimlessly and disorientated at his home. He had become more talkative, with out-of-context speech, had poor sleep and had become forgetful. He had become irritable and argumentative, prompting his wife to seek psychiatry advice. He had been previously well. It was uncertain whether or not he had been vaccinated according to the national immunisation programme during childhood.

Two years before this admission, he had been investigated for subacute, progressive, left-sided visual impairment. His visual acuities were 12/60 (left) and 6/6 (right). There was a left-sided relative afferent pupillary defect. An ophthalmologist investigated him for chorioretinitis, but all his investigations were normal, including antineutrophil cytoplasmic antibodies (c- and p-ANCA), cerebrospinal fluid (CSF) and MR scans of the brain and orbits. A short course of oral corticosteroids did not help and his vision gradually worsened. Six months later his visual acuities were 6/60 (left) and 6/6 (right). Funduscopy showed left-sided optic atrophy with subtle retinal pigmentary changes (figure 1).

Figure 1

Fundus photograph at 6 months after the visual symptoms shows optic atrophy of the left eye with subtle retinal pigmentary changes.

On examination during this admission, he was alert but uncooperative. Addenbrooke’s cognitive examination showed global cognitive impairment, scoring 28/100. His visual acuities were 1/60 (left) and 6/36 (right). There was a left-sided relative afferent pupillary defect. Funduscopy showed left optic atrophy and bilateral retinal scarring and pigmentation, predominantly involving the left perimacular retina, suggesting previous chorioretinitis (figure 2). The remaining neurological examination was normal.

Figure 2

Fundus photograph during the current admission shows significant atrophy of the left eye and bilateral retinal scarring and pigmentation predominantly involving the left perimacular retina suggesting old chorioretinitis.

Repeat MR scan of the brain showed T2 hyperintensities in periventricular region predominantly affecting the occipitoparietal lobes (figure 3). CSF was acellular with normal protein and glucose. Electroencephalogram (EEG) showed subtle generalised intermittent slowing with normal background. Measles antibody titre in both CSF and serum was >1/256.

Figure 3

Axial T2 fluid attenuation inversion recovery MR demonstrates widespread hyperintensities, mainly affecting posterior periventricular regions.

During the ward stay, his condition slowly deteriorated; he became increasingly drowsy and developed cortical blindness. At this stage, his family felt that further investigation and management would be unlikely to help, and they took him from hospital against medical advice.

Discussion

We describe a man with subacute sclerosing panencephalitis (SSPE), presenting as chorioretinitis 2 years before onset of other neurological features. SSPE is a progressive central nervous system disorder caused by persistent wild-type measles virus. Since Dawson’s first description of SSPE (1933) as a subacute inclusion body encephalitis, we now better understand the pathophysiology of this still incurable disease.1 Despite the substantial fall in worldwide incidence since the introduction of the measles vaccine, SSPE still occurs, particularly in low-income/middle-income countries.2

SSPE commonly affects children and young adults who have a history of primary measles infection before the age of 2 years. After a latent period of 6–8 years, patients typically present with behavioural changes with cognitive impairment, visual disturbances and myoclonus. The EEG characteristically shows generalised, symmetrical, high-voltage bursts of polyphasic sharp slow-wave complexes. The periodic complexes are usually time-locked to myoclonic jerks. Demonstrating raised antibody titres against measles in plasma and CSF confirms the diagnosis in the appropriate clinical setting.3

About half of patients with SSPE develop visual symptoms at some stage,4 usually developing concurrently with neurological symptoms. However, rarely these symptoms can precede the neurological manifestations by many years. Visual symptoms result from the measles virus damaging the visual pathways, from retina to occipital cortex. Retinal involvement characteristically presents as a focal necrotising retinitis, usually involving the macula. The macular and perimacular lesions begin as granular pigmentary changes and ultimately become gliotic retinal scars (figure 4) with disease progression. Other funduscopic findings include multifocal subretinal lesions, macular haemorrhage, oedema, papillitis, papilloedema and optic atrophy.5 Cortical involvement may cause homonymous visual field defects and cortical blindness.

Figure 4

Fundus photograph and fluorescein angiogram of another patient with similar presentations show typical macular pigmentary lesions suggesting old macular retinitis.

When SSPE presents typically with characteristic EEG changes, its diagnosis is straightforward. Nevertheless, a rare disease presenting with rare symptoms makes a clinical diagnosis very difficult. Our patient had many atypical features, making the diagnosis initially difficult. For example, SSPE generally occurs in childhood and adolescence, but this patient was aged 34 years when he developed visual symptoms. Also, he had neither myoclonus nor the typical EEG features. Furthermore, his visual symptoms preceded other neurological symptoms by almost 2 years.

Ocular presentations of SSPE are often (as here) misinterpreted as being caused by one of the inflammatory or heredodegenerative diseases of the retina. Ophthalmology texts rarely list SSPE as a differential diagnosis of macular retinitis. However, a previous encounter with similar presentation prompted us to consider SSPE as a possible diagnosis early, thereby avoiding unnecessary investigations and ineffective treatments.

In summary, ocular manifestations in SSPE may precede the more characteristic neurological symptoms. Clinicians, both ophthalmologists and neurologists, should consider SSPE among the differential diagnoses in chorioretinitis. This is particularly so if there is macular or perimacular involvement with concurrent involvement of the optic nerve in a young person, even without other characteristic neurological symptoms. Clinicians should then request plasma and CSF antimeasles antibody titres without hesitation.

Key points

  • Subacute sclerosing panencephalitis (SSPE) still occurs in many countries, particularly among people in overcrowded communities and those with insufficient measles vaccination coverage.

  • Ophthalmic symptoms of SSPE may precede other neurological symptoms by several years.

  • SSPE should be considered in the differential diagnosis of chorioretinitis, especially if this involves the macular or perimacular regions or if there is concurrent involvement of the optic nerve.

  • Awareness of ophthalmological manifestations of SSPE will lead to early diagnosis, thereby avoiding unnecessary investigations and ineffective treatment.

References

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Footnotes

  • Contributors VJ wrote the initial manuscript. AD revised and corrected the paper. All the authors agreed on final manuscript.

  • Competing interests None declared.

  • Patient consent Obtained from next of kin.

  • Provenance and peer review Not commissioned; externally peer reviewed. This paper was reviewed by Mark Lawden, Leicester, UK.

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