ABSTRACT
Leukoencephalopathy with brain stem and spinal cord involvement and high lactate (LBSL) include cerebral white matter, brain stem and spinal cord tract involvement on magnetic resonance imaging. Increased lactate levels on magnetic resonance spectroscopy (MRS) has been reported. In this case report, we describe a patient with LBSL and normal lactate levels on MRS.
Introduction
Leukoencephalopathy with brain stem and spinal cord involvement and lactate elevation (LBSL) is a rare, autosomal recessive disorder (1-3). Signal abnormalities in the cerebral white matter, medulla oblongata, lateral corticospinal tracts and dorsal columns of the spinal cord are the major diagnostic criteria of LBSL (4). Signal abnormalities in the cerebellar white matter, superior and inferior cerebellar peduncles, trigeminal tracts, splenium of the corpus callosum and posterior limb of the internal capsule are the supportive criteria of LBSL (4). On magnetic resonance spectroscopy (MRS) of the abnormal white matter there are usually increased lactate levels. (4). In this case report, we describe a patient with LBSL and normal lactate levels on MRS.
Case Report
A 15-year-old female patient had a seven years history of weakness in legs, postural instability and slurred speech. The symptoms were slowly progressive. There was no consanguinity in the family. Her medical history revealed that she had a loss of consciousness and vomiting at the age of six years after trauma.
Neurological examination at age 15 revealed a prominent weakness of the legs and increased tendon reflexes. Bilateral lower extremity muscle strength was reduced. Laboratory studies including complete blood count, glucose, cholesterol levels, vitamins, electrolytes and metabolic diseases tests were all normal.
The cranial magnetic resonance imaging (MRI) showed multifocal signal abnormalities as hyperintens on T2-weighted images and hypointense on T1- weighted images in the cerebral white matter (Figure 1), in the pyramids of medulla oblongata (Figure 2), in the dorsal columns and the lateral corticospinal tracts of cervical and thoracic part of the spinal cord (Figure 3).
There were also signal abnormalities in the splenium of the corpus callosum, posterior limb of the internal capsule (Figure 4), superior and inferior cerebellar peduncles (Figure 5) and cerebellar white matter (Figure 6). None of the lesions showed enhancement after gadolinium administration. The multivoxel MRS of the cerebral white matter lesions revealed decreased N-acetylaspartate, increased choline and normal lactate levels (Figure 7).
Discussion
LBSL is a rare, autosomal recessive disorder. Mutations in the DARS2 gene are associated with LBSL (1-3). Molecular genetic tests were not performed on the patient described in this article.
Signal abnormalities in the cerebral white matter, pyramids of the medulla oblongata, lateral corticospinal tracts and dorsal columns of the spinal cord are the major brain and spinal cord MRI diagnostic criteria of LBSL. For an MRI-based diagnosis, all major criteria should be completed (4-6). The cranial MRI of our patient showed presence of all the three major criteria which include multifocal, confluent abnormalities in the cerebral white matter, signal abnormalities in the pyramids of the medulla oblongata, and signal abnormalities in the dorsal columns and the lateral corticospinal tracts of cervical and thoracic part of the spinal cord.
Signal abnormalities in the cerebellar white matter, superior and inferior cerebellar peduncles, trigeminal tracts, splenium of the corpus callosum and posterior limb of the internal capsule are the supportive criteria of LBSL. For an MRI-based diagnosis, all major criteria and at least one supportive criterion should be completed (4-6). Cranial MRI of our case showed presence of five supportive criteria which include signal abnormalities in the splenium of the corpus callosum, posterior limb of the internal capsule, superior and inferior cerebellar peduncles and cerebellar white matter.
Lesions refers low signal on T1-weighted images and high signal on T2-weighted images (4-6). The patient described in this paper had the diagnostic MRI pattern of the disease.
On MRS of the abnormal white matter there are usually increased lactate levels. For an LBSL diagnosis, all major MRI criteria and at least one supportive criterion should be completed whether lactate is elevated or not (7-9). MRS findings, including decreased N-acetylaspartate and increased choline due to axonal degeneration (10). Our patient’s multivoxel MRS of the cerebral white matter lesions revealed decreased N-acetylaspartate, increased choline and normal lactate levels (Figure 8).
The disease spectrum ranges from neonatal to adult onset. Neonatal onset patients have a heavy disease course and may die, while adult onset disease is slowly progressive involving dysarthria, ataxia, spasticity, and epilepsy (11,12). Our patient is a 15-year-old female. She had a seven-year history of weakness in legs, postural instability and slurred speech. The symptoms had progressed slowly. Neurological examination at age 15 revealed a prominent weakness of the legs and increased tendon reflexes. Bilateral lower extremity muscle strength was reduced.
All major and five supportive MRI diagnostic criteria of LBSL in our patient were fulfilled, but MRS showed normal lactate levels in the affected cerebral white matter. A few radiological LBSL cases with genetic confirmation have been reported before with normal lactate levels (7,13,14). The reason of normal lactate levels is not yet known.
With this case report, we wish to underline that the LBSL with a distinct clinical and radiological presentation may have normal lactate levels in the affected cerebral white matter.
Ethics
Informed Consent: It was taken.
Peer-review: Externally and Internally peer-reviewed.
Authorship Contributions
Surgical and Medical Practices: Edis Çolak, Cenk Eraslan, Concept: Edis Çolak, Cenk Eraslan, Design: Edis Çolak, Cenk Eraslan, Data Collection or Processing: Edis Çolak, Cenk Eraslan, Analysis or Interpretation: Edis Çolak, Cenk Eraslan, Literature Search: Edis Çolak, Writing: Edis Çolak.
Conflict of Interest: No conflict of interest was declared by the authors.
Financial Disclosure: The authors declared that this study received no financial support.
