Enlarged cauda equina nerve roots in Cerebrotendinous Xanthomatosis

doi:10.4236/ojcd.2011.13006

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Open Journal of Clinical Diagnostics, 2011, 1, 26-28 OJCD

doi:10.4236/ojcd.2011.13006 Published Online December 2011 (http://www.SciRP.org/journal/ojcd/).

Published Online December 2011 in SciRes. http://www.scirp.org/journal/OJCD

Enlarged cauda equina nerve roots in cerebrotendinous

xanthomatosis

Peter Kalina

Division of Neuroradiology, Department of Radiology, Mayo Clinic, Rochester, USA.

Email: [email protected]

Received 20 October 2011; revised 29 November 2011; accepted 8 December 2011.

ABSTRACT

CXT is a rare inherited autosomal recessive lipid

storage disease due to the impaired metabolic path-

way of cholesterol secondary to a deficiency in 27-

sterol hydroxylase, an enzyme in the synthesis of

chenodeoxycholic acid (CDCA), a primary bile acid.

Abnormal bile acid synthesis leads to elevated plasma

Cholestanol (a derivative of cholesterol) accumula-

tion, especially in the lens, central nervous system

(CNS) and tend ons.

Keywords: Cerebrotendinous X anthomat osis; Cauda Equina;

Peripheral Neuropathy

1. CASE REPORT

A 41 year old male from Kuwait presented with imbal-

ance, lower extremity weakness and spasticity, difficulty

walking and standing. Physical examination revealed

hyperreflexia, positive Babinski sign, vibratory sensory

loss, bilateral pes cavus, arched feet, hammer toes, val-

gus deformity of the ankles, atrophic changes of the

calves and thighs, Achilles tendon nodules and bilateral

cataracts. EMG findings were compatible with periph-

eral neuropathy. Laboratory examination was notable for

elevated plasma cholesterol and increased urine bile al-

cohol. Serum enzyme studies confirmed the diagnosis of

Cerebrotendinous Xanthomatosis (CTX). Magnetic res-

onance imaging (MRI) of the brain and entire spin e with

contrast were normal with the exception of diffusely

thickened caud a equi na ne rv e roots (Figures 1 and 2).

2. DISCUSSION

The classic clinical triad of CTX is Achilles tendon xan-

thomas, juvenile cataracts and progressive neurological

impairment. These clinical hallmarks then prompt a

search for increased urine bile alcohol and serum cho-

lestanol. Most severely affected is the cerebellar white

matter, optic pathways, brainstem and spinal cord.

Ischemic heart disease, premature atherosclerosis and

osteoporosis are also seen. Onset of signs and symptoms

is usually in childhood with bilateral cataracts, diarrhea,

neurological abnormalities, tendon xanthomas, gait dis-

turbance, epilepsy and polyneuropathy [1].

CNS findings include myelin loss and axonal degen-

eration. Enzyme defect leads to accumulation of neuro-

toxic metabolites leading to neuronal loss and axonal

degeneration. It remains uncertain whether the pathology

is demyelination or neuroaxonal disease with secondary

myelin loss [2].

Peripheral neuropathy is manifest clinically as Pes

cavus, hammer toes, weakness of small intrinsic muscles

of the foot and foot drawn into a claw-like position.

EMG confirms the peripheral nerve damage as slow

motor/sensory conduction due to demyelinating neu-

ropathy. Sural nerve biopsy confirms demyelinating pe-

ripheral neuropathy [3].

MRI findings include symmetric T2 hyperintense le-

sions in the white matter of the cerebellum and spinal

cord and may also be present in the internal capsule,

dentate, globus pallidus, substantia nigra, inferior olive

as well as adjacent white matter, especially adjacent to

basal ganglia and infratentorial, consistent with demye-

lination. Atrophy may be seen in the cerebrum, cerebel-

lum, brainstem, corpus callosum and cervical cord. MRS

findings include decreased NAA reflecting neuronal and

axonal damage and increased lactate due to mitochon-

drial dysfunction from toxic effect of elevated cho-

lestanol and bile alcohol [4].

CDCA replacement therapy slows or reverses disease

progression including improving neurological function

by suppressing abnormal bile acid synthesis and reduc-

ing elevated cholestanol synthesis thus decreasing

plasma cholestanol and its deposition [5]. Xanthomas

slightly decrease in size. Electrophysiologic studies im-

prove with reduced nerve conduction velocity; slowed

somatosensory evoked potentials. Diag nosis and therapy

are evaluated by serum cholestanol/cholesterol and ur ine

P. Kalina / Open Journal of Clinical Diagnostics 1 (2011) 26-28 27

(a) (b) (c)

Figure 1. Sagittal T2 weighted images demonstrating diffusely thickened cauda

equina nerve roots.

(a) (b) (c) (d)

Figure 2. Axial T2 weighted images confirm the cauda equina nerve root thickening.

excretion bile alcohols.

There are only approximately 300 reported cases of

Cerebrotendinous Xanthomatosis. This is likely at least

in part due to underdiagnosis and misdiagnosis. While

there have been previous descriptions of patients with

peripheral neuropathy [6-7], ours represents the only

case of CTX where the imaging findings were all en-

tirely normal with the exception of changes consistent

with peripheral neuropathy manifest as thickened cauda

equina nerve roots. In the appropriate clinical setting,

CTX should be included in the differential diagnosis of

enlarged cauda equina nerve roots. Conversely, absence

of other typical imaging findings of CTX should not

exclude the diagnosis in the appropriate clinical setting.

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