Indian Journal of Radiology and Imaging Indian Journal of Radiology and Imaging

QUIZ
Year
: 2003  |  Volume : 13  |  Issue : 3  |  Page : 345--346

Radiological quiz - brain


R Kumari, R Gupta, V Chowdhury 
 Dept of Radiodiagnosis, M.A.M.C. and Lok Nayak Hospital, Jawahar Lal Nehru marg, Delhi 110002, India

Correspondence Address:
R Kumari
198, Gagan Vihar, Delhi 110051
India




How to cite this article:
Kumari R, Gupta R, Chowdhury V. Radiological quiz - brain.Indian J Radiol Imaging 2003;13:345-346


How to cite this URL:
Kumari R, Gupta R, Chowdhury V. Radiological quiz - brain. Indian J Radiol Imaging [serial online] 2003 [cited 2021 Jan 22 ];13:345-346
Available from: https://www.ijri.org/text.asp?2003/13/3/345/30485


Full Text

A forty year old woman presented with progressive weakness of both upper limbs with associated atrophy of the forearm and hand muscles since six months. On clinical examination there was mild increase in tone of both lower limbs with exaggerated deep tendon reflexes. There was no history of fever or any craniospinal trauma. The patient underwent an MR examination of the brain [Figure 1]a&b,[Figure 2].

 View Answer

 Radiological Diagnosis



 Amyotrophic Lateral Sclerosis



MR imaging revealed illdefined areas of increased signal intensity at the junction of the centrum semiovale and corona radiata bilaterally. Strikingly sharp and symmetrical foci of abnormal signal intensity were seen within the posterior limbs of both internal capsules. T2 weighted scans also disclosed high signal areas along the large myelinated pyramidal tract fibres in the cerebral peduncles.

The differential diagnosis includes adult onset Krabbe's disease (globoid cell leukodystrophy), progressive multifocal leukoencephalopathy and Wallerian degeneration. However, the typical clinical presentation and MR findings indicated a diagnosis of amyotrophic lateral sclerosis.

ALS is the most common type of degenerative motor neuron disease, characterized predominantly by degeneration of both the corticospinal tracts as well as lower motor neurons [1]. Mean age at diagnosis is 57 years, most cases are sporadic; 5% are inherited in an autosomal dominant fashion. The clinical triad of atrophic weakness of the hands and forearms, spasticity of the legs and generalized hyperreflexia is characteristic. Disease progression is relentless; half the patients are dead within three years and 90% within six years following symptom onset [2].

Microscopic examination shows motor neuron loss and accumulation of spheroids composed of neurofilaments in remaining motor neurons. There is loss of myelin and increased water content along the course of the motor axons. On MR, corresponding hyperintense foci are seen on long TR sequences along the course of the corticospinal tracts from the precentral gyrus to the level of the cord.

In younger patients with more severe clinical involvement there may be presence of nonspecific white matter changes [3]. Variable loss of motor neurons is seen in brainstem nuclei, particularly of the hypoglossal motor neuron cells resulting in neurogenic atrophy of the tongue [4].

Some cases of ALS demonstrate reduced signal intensity within involved cortex on T2 weighted images reflecting an increased concentration of minerals associated with neuronal degeneration. This finding is typically uniform and laminar but localized, often affecting the precentral gyrus.

In conclusion, it is important to be acquainted with the various imaging characteristics of ALS and to have a high level of suspicion for detecting ALS especially in patients presenting with combined upper and lower motor neuron signs. MRI is the best noninvasive method for detecting and diagnosing ALS and should be used in all patients presenting clinically with motor neuron dysfunction.

References

1Adams RD, Victor M. Principles of Neurology. 4th ed. New York: Mc Graw-Hill Information Services Company, Health Profession Division; 1989: 35-77, 334-346, 921-967.
2Udaka F, Sawada H, Senv N et al. MRI and SPECT findings in Amyotrophic lateral sclerosis. Neuroradiol 1992; 34: 389-393.
3Iwasaki Y, Kinoshita M, Shiojima T. MRI in primary layeral sclerosis. Neurology 1991; 41: 951 (abst.).
4Cha CH, Patten BM. Amyotrophic lateral sclerosis: abnormalities of the tongue on magnetic resonance imaging. Ann Neurol 1989; 25: 468-472.