A 32-year-old Afro-Caribbean male presented with a three-month history of blurred vision and a two-month history of bilateral leg weakness accompanied by a painful burning sensation in his feet and a painful skin rash on the lower limbs.
He had no significant past medical history and had an extensive family comprising of 10 sisters, five brothers and six children (three male, three female) whom he stated were all fit and well.
He took no regular medication and denied any allergies. He was originally from Jamaica and had been resident in the UK for nine years. He denied any recent foreign travel. He did not work and was the sole carer for his six children. He smoked approximately five cigarettes a day, as well as twice-weekly cannabis. He consumed alcohol rarely and denied any further recreational drug use. He was a strict vegan consuming no meat, fish, eggs or dairy products, after adopting the Rastafarian religion one-year previously. His diet consisted of nuts, pulses, seeds, a variety of fruit and vegetables, as well as tofu, soya products, rice, whole-grain bread and cereals, including some fortified products occasionally and vegetable oils.
On presentation, opthalmological examination revealed corneal changes consistent with punctate epitheliopathy. Visual acuity was impaired to the extent of being able only to count fingers at the bedside and was subjectively slightly worse on the right than the left; it did not improve with refraction. Pupils were equal and reactive with a right-sided afferent pupillary defect. Slit lamp examination revealed temporal disc pallor with a pigmentary scar in the right infero-temporal retina. Cranial nerve examination was otherwise unremarkable.
Neurological Examination of the upper limbs was normal. Examination of the lower limbs revealed proximal weakness with preserved reflexes and equivocal plantars. He had subtle impairment of proprioception to the ankle with impaired light touch, vibration and pin prick in a stocking distribution. He walked with an ataxic and antalgic gait.
Dermatological examination revealed a tender nodular eruption with small vesicles on top of some lesions over the lower legs bilaterally. There were no other muco-cutaneous lesions, and cardiovascular, respiratory and abdominal examinations were all unremarkable.
BMI was calculated at 21. Full blood count, urea and electrolytes and liver function tests were normal; haemoglobin was 15.6 (normal 13.0-17.0 g/dl), creatinine 80 (normal 59-104 umol/L), albumin 50 (normal 40-52 g/L) and total protein 67 (normal 60-85 g/L). Coagulation screen was normal with an INR of 0.97 (normal 0.90-1.10), APTT 1.01 (normal 0.8-1.16) and fibrinogen 3.39 (normal 1.67-5.43). Inflammatory and auto-immune profiles (anti-neutrophil antibodies, anti-nuclear antibody, ENA antibody, ESR and CRP) were normal aside from a very weakly positive antinuclear antibody with speckled pattern. Serum vitamin B12 was moderately low at 111 (normal 145-1000 ng/L), folate was normal at 3.8 (normal 2.5-16.0 ug/L). Iron studies were normal; Iron 21.0 (normal 14.0-31.0 umol/L), total iron binding capacity 64 (normal 41-77 umol/L), transferrin saturation 60 (normal 18-71%). Serum calcium was 2.21 corrected (normal 2.15-2.55 mmol/L) and phosphate 1.2 (normal 0.9-1.4 mmol/L). The following investigations were all negative: serum ACE, Treponema pallidum, antibodies and HIV. Goldmann visual field assessment revealed constricted visual fields bilaterally, with a small central scotoma.
An MRI scan of the brain was normal. In particular there was no parenchymal or meningeal enhancement and optic nerve sheath complexes were normal with no contrast enhancement. The cavernous sinuses were normal and there were no retro-orbital mass lesions. MRI of the whole spine revealed no significant abnormality.
There were no features to suggest a motor or sensory neuropathy on electromyography (EMG) or nerve conduction studies, although thermal thresholds to assess for a small fibre neuropathy were not performed.
A dermatological review suggested a folliculitis and skin biopsy was felt to be consistent with this, although changes in the subcutis were indicative of a non-specific lobular panniculitis.
A Schilling test was not performed as the B12 deficiency was thought to be nutritional in origin and full audiological testing was not undertaken as the patient reported no hearing impairment. CSF examination was not performed during this admission and the patient declined genetic testing for Leber's hereditary optic neuropathy (LHON).
A diagnosis of Optic and Peripheral Neuropathy was made, which was thought to be nutritional in origin, and the patient was commenced on Intravenous B vitamins and Vitamin B12 intra-muscular injections. He was discharged home on Folate and Vitamin B Co-Strong tablets, Gabapentin and Amitryptyline for neuropathic pain and Vitamin B 12 intra-muscular injections on alternate days for two weeks and then twice monthly after this.
He was reviewed as an outpatient two months after discharge and he reported no improvement to his vision or lower limb weakness and pain.