Why the burning sensations in the arms?
Vol.16, No.12, December 2008

This 33-year-old woman presented to her family doctor with a progressive headache, intermittent ataxia, upper extremity weakness and paresthesia, and 2 episodes of syncope following sneezing. All blood tests came back within normal range. She had no prior history of cancer or other major medical problems. A magnetic resonance image (MRI) of the head and cervical spine was ordered.

The most likely diagnosis of this woman’s complaints is:

a) Arnold-Chiari malformation Type I

b) Guillain-Barré syndrome

c) intramedullary astrocytoma

d) multiple sclerosis

e) mid-cervical disc herniation producing focal cord myelopathy

ANSWER
Solution TO Analyze This!

The most likely diagnosis is: (a) Arnold-Chiari malformation Type I

Figure 1a reveals inferior herniation of the cerebellar tonsils into the upper cervical canal, along with extensive lobulated syringomyelia of the cervical cord (see Figure 1b), characteristic of Arnold-Chiari Type I malformation. Arnold-Chiari malformation is a moniker attributed to a series of central nervous system disorders involving the posterior fossa and spinal canal. A German pathologist named Hans Chiari described a few anomalies on cadaveric specimens and the descriptions were enhanced by another pathologist, named Julius Arnold, years later. Thus, the Arnold-Chiari connection was born, although the two never worked together. The descriptions of each sub-type are as follows:

Arnold-Chiari Type I: a narrow posterior fossa results in inferior herniation of the cerebellar tonsils into the upper cervical canal, compressing the cervical spinal cord. This can be associated with upper cervical vertebral anomalies and syringomyelia (dilatation of the central CSF channel within the cord, producing elongated fluid pockets, as shown in Figure 1b). The abnormality is usually congenital but has been described as a complication in bone disorders such as calvarial Paget’s disease

Arnold-Chiari Type II: downward displacement of the cerebellar tonsils associated with lower spinal myelomeningocele

Arnold-Chiari Type III: severe upper cervical spina bifida and/or posterior fossa calvarial defect resulting in high cervical or low occipital encephaloceles

Arnold-Chiari Type IV: Later publications described severe hypoplasia of the posterior fossa resulting in inferior cerebellar tonsillar herniation with no other accompanying anomalies. Types III and IV are rare.

Some patients with Arnold-Chiari Type I malformation may live their entire lives asymptomatic and undetected. However, the condition can also progress and symptoms may become severe enough to warrant neurosurgical decompression, with variable results, depending on the severity and the secondary sequelae of the underlying pathology.

Guillain-Barré syndrome is an acute inflammatory demyelinating polyneuropathy, an autoimmune disease usually triggered by a viral infection, resulting in ascending paralysis. It can be reversible if treated early enough with plasmapheresis or IV immunoglobulins. Enhanced MRI may reveal nerve root sheath enhancement and spotty cord changes, along with potential brain white matter foci.

Intramedullary astrocytoma can reveal a focal cord lesion and be associated with a prominent secondary cord syrinx but won’t have associated cerebellar tonsil herniation.

Multiple sclerosis can reveal focal hyperintense (bright) cord lesions on T2-W MRI but an associated syrinx is rare and again it will not have associated cerebellar tonsil herniation.

There is no mid-cervical disc herniation present, and in fact no cervical degenerative change present at all, so choice 5 is out from the start.

 

References:

  1. McGirt MJ et al. Neurosurg 2006;59(1):140-6.
  2. Richards PS, et al. Am J Roentgenol 2001;176:816-7.
  3. Ergun R, et al. Eur Spine J 2000 Dec;9(6):553-7.
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Clinical challenge image

Figure 1a: Sagittal T2-W MRI of cervical spine revealing portion of posterior fossa, cervical cord and vertebrae.

Clinical challenge image
(top arrow)Inferior herniation of cerebellar tonsils (bottom arrows)Widening of cervical cord secondary to long, lobulated syrinx

Figure 1b: Identical to Figure 1a, with the addition of select anatomical/pathological labels.

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