Patient had memory impairment and diminished vision.
There are areas of hyperintensity on the T2W and FLAIR images involving the white matter in the temporo-occipito-parietal lobes. These are hypointense on the T1W images and show peripheral enhancement on contrast administration. Also seen was involvement of the splenium of the corpus callosum and corticospinal tracts in the brainstem.
Adrenoleukodystrophy (ALD) is one of a group of genetic disorders called the leukodystrophies that cause damage to the myelin sheath. People with ALD accumulate high levels of saturated, very long chain fatty acids (VLCFA) in the brain and adrenal cortex because they do not produce the enzyme (deficiency of long-chain fatty acid CoA synthetase) that breaks down these fatty acids in the normal manner. The loss of myelin and the progressive dysfunction of the adrenal gland are the primary characteristics of ALD. ALD has two subtypes. The most common is the X-linked form (X-ALD), which involves an abnormal gene located on the X-chromosome. Women have two X-chromosomes and are the carriers of the disease, but since men only have one X-chromosome and lack the protective effect of the extra X-chromosome, they are more severely affected. Onset of X-ALD can occur in childhood or in adulthood. The childhood form is the most severe, with onset between ages 4 and 10. The most common symptoms are usually behavioral changes such as abnormal withdrawal or aggression, poor memory, and poor school performance. Other symptoms include visual loss, learning disabilities, seizures, poorly articulated speech, difficulty swallowing, deafness, disturbances of gait and coordination, fatigue, intermittent vomiting, increased skin pigmentation, and progressive dementia. In the milder adult-onset form, which typically begins between ages 21 and 35, symptoms may include progressive stiffness, weakness or paralysis of the lower limbs, and ataxia. Although adult-onset ALD progresses more slowly than the classic childhood form, it can also result in deterioration of brain function. The abnormal genes that cause neonatal ALD are not located on the X-chromosome, which means that both male and female babies can be affected. Symptoms include mental retardation, facial abnormalities, seizures, retinal degeneration, weak muscle tone, enlarged liver, and adrenal dysfunction. This form usually progresses rapidly. A mild form of ALD is occasionally seen in women who are carriers of the disorder. Symptoms include progressive stiffness, weakness or paralysis of the lower limbs, ataxia, excessive muscle tone, mild peripheral neuropathy, and urinary problems.
Adrenomyeloneuropathy, an adult variant of the same disease, usually presents in the third or fourth decade of life and predominantly affects the peripheral nervous system. It is characterized by adrenal insufficiency, hypogonadism, spastic paraparesis, and distal polyneuropathy.
Pathology:
Histopathological features of this disorder include demyelination and axonal loss in white matter.
On MRI:
Hyperintense areas on the T2W and FLAIR images are seen to involve the white matter, developing in a dorsoventral distribution and involving the splenium of the corpus callosum. Involvement of the corticospinal tracts and of the optic and auditory pathways also is frequently demonstrated. After administration of gadolinium chelates, enhancement in the areas with active demyelination and inflammation may be seen. The more central areas of involvement that are completely demyelinated do not enhance, nor do the most peripheral areas of involvement, which are less heavily demyelinated. Less frequently, the frontal and parietal white matter may be predominantly involved or the disease may show a unilateral distribution. The pattern of bilateral occipital white matter involvement in adrenoleukodystrophy is so well known that cases with atypical patterns of white matter involvement are often misdiagnosed, or diagnosis is significantly delayed. The finding of pontomedullary corticospinal tract involvement, when found in boys with developmental delay, impaired attention, or worsening school performance, can be extremely useful in making a diagnosis of adrenoleukodystrophy.
D. J. Loes, et al, have grouped MRI abnormalities into five groups based on the anatomic location of the initial T2 signal hyperintensity (pattern 1: parieto-occipital white matter, pattern 2: frontal white matter, pattern 3: corticospinal tract, pattern 4: cerebellar white matter, pattern 5: concomitant parieto-occipital and frontal white matter). Pattern 1 patients had rapid progression if contrast enhancement was present and if the MRI abnormality manifested at an early age. The latter was also true for pattern 2 patients. Based on these variables, predictive formulas were constructed for these two patterns using multiple regressions. MRI progression was much slower in pattern 3 and 4 patients, whereas in the pattern 5 patients, it was more rapid than in any other of the patterns. Patterns 1 and 5 occurred mainly in childhood, patterns 2 and 4 in adolescence, and pattern 3 in adults.
Significantly decreased N-acetyl-aspartate (NAA)/Creatin (Cr), increased Choline (Cho)/Cr and Myo-inositol (MI)/Cr may be seen in the involved white matter on MR spectroscopy.
In adrenomyeloneuropathy the brain MRI may be normal or may demonstrate findings similar to those seen in adrenoleukodystrophy, although involvement is less pronounced and more cerebellar. Spinal involvement may be seen.