26th Apr 2021

ICRI CASE OF THE WEEK

Contributed By : Dr. Vardhan Joshi, Consultant and Head
Department of Radiology, Sahyadri Specialty hospitals, Pune

Copyright of the Case belongs to : Dr Vardhan Joshi

History

• 24 y/M presented with weakness of right hand since 3 years and left hand
since 1 year.

• Started noticing distal weakness of right upper limb which was gradually
progressive, and since last 2 years started noticing wasting also.

• Exaggeration of weakness in cold [cold paresis].

On Examination

• Weakness and wasting of thenar and hypothenar muscles.
• Weakness of wrist flexors > extensors on right.
• Weak left interossei.
• Oblique atrophy of right upper limb.



• Can you
make out any
abnormality
on this MRI
study of the
cervical
spine?

• MRI
cervicothoracic
spine in neutral
position showed
mild reduction
in caliber of
cervical cord at
C6 vertebral
level with
minimal cord
edema.

• Based upon strong clinical suspicion of Hirayama’s disease,
Flexion MRI was done which showed –

1] Effacement of posterior subarachnoid space.
2] Multiple prominent vascular flow voids in the posterior epidural space with

prominence of the epidural space.
3] The posterior portion of the cervical cord appeared compressed at C5, C6

and C7 vertebral levels.
4] There was effacement of anterior subarachnoid space as well.
5] Post contrast study showed intense enhancement of the posterior epidural

fat pad and posterior epidural veins.











Hirayama Disease

[described by Keizo Hirayama in 1959]

• Non-progressive juvenile spinal muscular atrophy.
• Cervical myelopathy related to flexion movements of the neck.
• Benign motor neuron disorder.

Clinical Features-

• Insidious onset.
• Predominantly unilateral upper extremity weakness and atrophy.
• Cold paresis.
• Muscle weakness and atrophy of hand and forearm (mainly muscles

which are innervated by C7,C8 and D1 roots)
• Brachioradialis and proximal muscles of upper limbs may be spared

(those which are innervated by C5-C6 roots).
• Young adolescents 15-25 yrs age group. M>F
• Self limiting course, spontaneously halts after period of 5 yrs in 90% pts.

Pathology

• The proposed mechanism is that the dura does not increase in length
in the same proportion as rest of the spinal elements. Hence the dura
is already taut during neutral position and is unable to fully
compensate for dynamic increases in posterior length during flexion.

• During flexion, the relatively short dura becomes further taut and has
to shift forward. There is resultant obliteration of posterior
subarachnoid space with the dura closely abutting the posterior cord
surface. There is widening of posterior epidural space with engorged
posterior epidural venous plexus.

• Resultant anterior displacement of cord results in obliteration of
anterior subarachnoid space. It is believed that chronic
microcirculatory changes in the territory of the anterior spinal artery
induced by repeated or sustained flexion account for the necrosis of
the anterior horn cells of the lower cervical cord.

• Angiographic case reports have shown that arterial spinal flow is not
obstructed, it is thought to result from repetitive mechanical
compression and/ or venous congestion.

Treatment

• Dependent on early recognition and consists of conservative
treatment with cervical collar placement to avoid neck flexion.

• Decompressive surgery is controversial and only advocated for
patients with persistent deterioration despite treatment.

Teaching Points

• Strong clinical suspicion of Hirayama disease in the typical setting is
very helpful to decide regarding Flexion MRI before the patient is
taken for MRI study.

• Reduction in the caliber of lower cervical cord with or without
intramedullary T2 hyperintensity should prompt the radiologist to be
vigilant and Flexion MRI should be considered in the appropriate
clinical settings.

References

• The Importance of Flexion MRI in Hirayama Disease with Special Reference to
Laminodural Space Measurements. D.K. Boruah, A. Prakash, B.B. Gogoi, R.R. Yadav, D.D.
Dhingani and B. Sarma. American Journal of Neuroradiology March 2018, DOI:
https://doi.org/10.3174/ajnr.A5577

• NK, Vottath S, Purkayastha S. Imaging features in Hirayama disease. Neurol India
2008;56:22-6

• Cervical Spine MR Imaging Findings of Patients with Hirayama Disease in North
America: A Multisite Study. V.T. Lehman, P.H. Luetmer, E.J. Sorenson, R.E. Carter, V.
Gupta, G.P. Fletcher, L.S. Hu and A.L. Kotsenas. American Journal of
Neuroradiology February 2013, 34 (2) 451-456; DOI:
https://doi.org/10.3174/ajnr.A3277