Teaching Case

A 73-year-old woman presented at our department with recent history of trauma (two days before) and a short history of bilateral leg weakness. X-ray of lumbar spine showed a fracture and after orthopaedics evaluation, an MRI of the lumbar spine was requested to investigate the age of the fracture and any cord compression.

Old fracture of L1 first lumbar vertebra depicted with no oedema on STIR sequence and without central canal stenosis (Fig. 1). Nevertheless there was high signal in the dorsal segment of conus medullaris (Fig. 2).
Therefore the examination was followed by MRI of the thoracic spine, which revealed continuation of the abnormal signal in the thoracic cord with symmetric bilateral high signal within the dorsal columns of the spinal cord in the thoracic region (Fig. 3, 4, 5).

A. Background
Sub-acute combined degeneration of the cord is related to B12 deficiency. As vitamin B12 is mainly absorbed in the terminal ileum, causes of terminal ileitis including Crohn disease, coeliac disease and surgery involving terminal ileum can cause B12 deficiency, same as atrophic gastritis [1].
B. Clinical Perspective
Neurological features related to vitamin B12 deficiency can include signs of loss of position and vibration sense and ataxia, spasticity, hyperreflexia and positive Babinski sign [1]. In our case the patient was also evaluated by a neurologist. Sensory innervation, cerebellar tests and the patient's deep tendon reflexes were normal while mild bilateral leg weakness was observed. The patient complained that she suffered from difficulty in walking and epigastralgia for the past three months. The neurologist requested a B12 blood test, getting a result of 96 pg/ml (normal range values 196-866).
C. Imaging Perspective
On imaging studies it presents usually with symmetric bilateral high signal within the dorsal columns of the spinal cord in the thoracic region, less frequently the lateral tract can be affected.
Extremely rarely, anterior cord involvement can take place [2]. Usually these areas have no contrast enhancement. In some cases cerebral white matter may be involved [1].
D. Outcome
B12 deficiency is treated with B12 intramuscular injections, which may be required monthly for life. Although MRI high signal usually disappeares after treatment, symptoms and clinical signs may persist [1]. In our case the patient was also treated with intramuscular hydroxocobalamine (5 mg per injection) once daily for 5 days, followed by one injection weekly for 4 weeks and by one injection monthly thereafter. Later during the management of the patient endoscopy revealed gastric cancer, which was also depicted as abnormal wall thickening of the stomach's pyloric antrum in computed tomography for staging of the disease (Fig. 6). Partial gastrectomy was done, nevertheless, due to co-morbidity reasons the patient passed away after few months.
E. Take Home Message, Teaching Points
As the improvement of the clinical symptoms depends on the duration and severity of clinical symptoms, early diagnosis is needed in order to have a better clinical outcome [1].
MR findings usually include symmetric bilateral high signal within the dorsal columns of spinal cord in the thoracic region while during the course of the disease the signal changes may extend upwards and involve the cervical cord, as well as the lower thoracic cord [3].

Written informed patient consent for publication has been obtained.