Spontaneous conus infarction with "snake-eye appearance" on magnetic resonance imaging: A case report and literature review

Table 1 Overview of reported cases of conus infarction

Ref.	Age/gender	Risk factors	Pathogeny/mechanism	Prognosis	MRI findings
					T2WI I high signal (Axial)	T2WI high signal (Sagittal)	DWI high signal	Involve centrum/muscle/ligament
Herrick et al[5]	84/M	NA	Aortic dissection aneurysm	Partial improvement, died of rupture of aortic dissection aneurysm on the 18th day of admission	NA	NA	NA	NA
	79/M	Heart failure	Aortic atherosclerosis	No improvement, died of acute myocardial infarction on the 25th day of admission	NA	NA	NA	NA
Anderson et al[6]	54/M	Coronary diseaseHeart failure	Aortic balloon pump implantation	Some improved strength in the legs before death 7 wk after the ictus	NA	NA	NA	NA
	75/M	Smoking	Repair operation of abdominal aortic aneurysm	Persistent urinary incontinence with some improvement in bowel function and in motor and sensory signs 16 mo after the ictus	NA	NA	NA	NA
	66/M	Smoking	Aortic atherosclerosis	Some functions recovered 2 mo after the ictus	NA	NA	NA	NA
	51/M	Smoking	NA	Persistent urinary incontinence with some functions recovered 28 mo after the ictus	NA	NA	NA	NA
	47/F	NA	NA	No improvement in 2 yr	NA	NA	NA	NA
Ohbu et al[7]	69/F	Hypertension	NA	NA	NA	NA	NA	NA
Andrews et al[8]	71/F	NA	NA	Walking independently, mild hypoesthesia, but persistent urinary incontinence 2 mo after the ictus	NA	NA	NA	NA
Mhiri et al[9]	28/M	NA	Dural arteriovenous fistula	No improvement	NA	NA	NA	NA
Sinha et al[10]	63/M	HypertensionCoronary disease	Coronary artery bypass grafting (CABG)	persistent urinary incontinence 5 yr after the ictus	NA	NA	NA	NA
Greiner-Perth et al[11]	66/M	NA	NA	No improvement in 8 mo	NA	T12-L1	NA	NA
Combarros et al[12]	69/F	Hypertension	NA	The bladder function returned to normal and can walk with a walker 2 mo after the ictus	NA	NA	NA	NA
Wildgruber et al[13]	44/F	NA	Spinal venous thrombosis	Motor function recovered partially and leaving hypoesthesia 6 mo after the ictus	Bilateral anterior horn of gray matter (Snake-eye appearance)	T12-L1	NA	NA
Wong et al[14]	79/F	Coronary disease	Aortic atherosclerosis	Partial neurologic recovery	Bilateral gray matter and central white matter	T12-L1	Yes	NA
Konno et al[15]	77/F	Hypertension	Spinal venous thrombosis	Symptoms improved rapidly	Diffuse	L1	NA	Yes
Diehn et al[16]	24/M	NA	Fibrocartilage embolism	No improvement	Bilateral anterior horn of gray matter	T10-L1	NA	Yes
Alanazy[17]	48/M	NA	Overstretch	Walking resumed on day 105	Diffuse	T11-L1	NA	NA
Hor et al[18]	51/F	NA	NA	NA	Bilateral gray matter and central white matter	T12	NA	NA
Kamimura et al[19]	70/F	NA	Spinal venous thrombosis	Sensory disturbance improved, leaving numbness in the sellar area and urinary incontinence	Bilateral posterior funiculus, right posterior horn, right lateral funiculus	T12	NA	Yes
Weng et al[20]	55/M	Hyperlipidemia	Sofa sedentary	Calf muscle atrophy, perianal hypoesthesia and neurogenic bladder 3 yr after ictus	Bilateral anterior horn of gray matter	T11-12	Yes	Yes
	34/F	NA	Toilet sedentary	Calf muscle atrophy, perianal hypoesthesia and neurogenic bladder 4 yr after ictus	NA	T12	Yes	NA
Breitling et al[21]	52/M	NA	NA	Motor function recovered partially, leaving bladder and rectum dysfunction	Bilateral anterior horn of gray matter (Snake-eye appearance)	L1	NA	Yes

DWI: Diffusion-weighted imaging; NA: Not available.

Table 2 Identification of common diseases related to snake eye sign

Disease	Clinical features	Magnetic resonance performance	Neuroelectrophysiological manifestations
Conus medullaris infarction[38]	The main manifestations are sensory disturbance in the sellar region, bladder and rectal incontinence, bulbar anal reflex weakening or disappearing, erectile dysfunction, root neuralgia and lower limb motor neuron paralysis when combined with cauda equina damage	T12-L1 horizontal magnetic resonance T2WI and DWI high signal, T1W1 low signal	There are few reports about the neurophysiological characteristics of conus medullaris infarction. The reappearance of F wave after infarction may mark the improvement of clinical prognosis
Hirayama disease[39]	The self-limited disease, which is mainly characterized by unilateral muscle atrophy of the distal end of the upper limb, mainly affects the intrinsic muscles of the hand and forearm muscle groups. Typical clinical manifestations also include "cold paralysis", "finger extension tremor" and "muscle bundle tremor"	Asymmetric cervical spinal cord flattening, atrophy and intramedullary T2W1 high signal in cervical flexion position, disappearance of cervical physiological flexion, expansion and increase of epidural venous plexus, and anterior displacement of dural sac after over-extension and over-flexion position	The neurogenic damage of the affected muscle group mainly occurred in the C7-8 sarcomere and T1 sarcomere, while the C5-6 sarcomere (i.e. deltoid, biceps brachii and radial brachii) was not affected
Amyotrophiclateralsclerosis[34]	Malignant degenerative motor neuron disease characterized by multiple or localized progressive muscular atrophy and apraxia is characterized by limb spasms, tendon hyperreflexia, localized or multiple muscle weakness, muscular atrophy and fascicular tremor	T2WI, FLAIR and DWI can find symmetrical high signal in the pyramidal tract of the brain. In a few patients, SWI can see the deposition of hemosiderin along the motor cortex	The muscles innervated by different nerve segments of medulla oblongata, neck, chest and lumbosacral appear progressive denervation and chronic nerve regeneration
Cervical spondylotic myelopathy[40]	Based on cervical degeneration, the main manifestation is atrophy of the proximal or distal muscles of the upper limb, which usually occurs in one side, usually without sensory abnormalities	It is usually manifested as spinal cord thinning, intervertebral disc protrusion or prolapse. Due to long-term compression of the spinal cord, venous hyperemia and infarction can be caused, which can be secondary to cystic necrosis of the anterior horn of the spinal cord, forming T2WI snake-eye sign	Segmental neurogenic damage consistent with the distribution of the injured nerve root
Spinal muscular atrophy syndrome[41]	The most common autosomal recessive disease in childhood is progressive and symmetrical weakness and atrophy of limbs and trunk muscles	Anterior horn of spinal cord α- Degeneration and degeneration of motor neurons led to T2WI snake-eye sign	Typical neuronal damage, fiber fibrillation wave and positive sharp wave can be seen at rest, bundle fibrillation potential can be seen occasionally, and regular spontaneous motor unit activity potential is the characteristic manifestation of its EMG

DWI: Diffusion-weighted imaging; EMG: Electromyography; FLAIR: Fluid-attenuated inversion-recovery; SWI: Susceptibility weighted imaging; T2WI: T2-weighted imaging.