Brain MRI to see the "traitor head" sign? Image representation

Recently met 1 patient, the imaging performance is amazing, manifested as a semi-annular FLAIR high-intensity foci around the brainstem, diffusion is limited, not strengthened, the image is called "traitor head sign", further examination for lung cancer meningeal metastasis, Professor Tang Wei of the Department of Neurology, Xinhua Hospital Affiliated to Dalian University led everyone to a detailed analysis
.

Case review

Patient, female, 59 years old, married
.

16 days ago(2021.
6.
20)

The patient's family found that the patient was sitting on the balcony, stimulated and exhaled, accompanied by urinary incontinence, and then relieved on its own, and could not recall
the situation.

After regaining consciousness, the family found that the patient's voice was significantly larger than before, the speech was confused, and some family names were difficult to remember, accompanied by unstable
walking.
No dizziness, headache, nausea, vomiting, confusion, slurred speech, difficulty swallowing, choking on water, no chest tightness, shortness
of breath.

On the same day, go to the local hospital, perform head DWI examination to show abnormal signals at the brainstem parenchymal margin, consider infarction (acute stage), and do not exclude the possibility of
metabolic diseases.

10 days later (2021.
6.
30)

There was no change in reexamination of head MR, and intravenous fluid therapy (details unknown) was not
effective.

Admitted to our hospital(2021.
7.
6)

In order to seek further diagnosis and treatment, the main reason was "cognitive dysfunction with unstable walking for 16 days" was admitted, and the outpatient clinic was "cognitive dysfunction? Cerebrovascular disease? "Take in my ward
.
Since the onset of the disease, the appetite is good, the mental rest is average, and the urine and urine are normal
.

Neurological examination

Mental clarity, thinking, comprehension, memory and calculation ability are slightly reduced
.
Speak fluently and speak clearly
.

The orientation is normal, the rough binocular vision and hearing in both ears are basically normal, and there is no dizziness and nystagmus
.

The uvula is centered, there is no hoarseness, no difficulty swallowing, and no coughing
with water.
Bilateral shoulder shrugs, symmetrical neck
turn.

The tongue is centered, the tongue muscle is not atrophied, and no fasciculation
is seen.

The muscle strength of the limbs was 5 levels, the muscle tone was not increased or decreased, there was no involuntary movement, and the finger nose test, finger finger test, rotation test and heel knee shin test were all coordinated and accurate
.

There were no abnormalities
in the depth of the trunk and limbs.
Bilateral biceps reflexes, triceps reflexes, radioperiosteal reflexes, knee tendon reflexes, and Achilles tendon reflexes are normal and symmetrical, abdominal wall reflexes are normal, no patellar clonic and ankle-clonic, bilateral Hoffmann signs are negative, left Babinski signs are positive, and right is not elicited out
.
There is no resistance to neck softness, and Kernig's sign and Brudzinski sign are negative
.

Auxiliary examinations

Lung CT shows left upper lobe lung cancer
.
MRI of the head (2021.
6.
20): abnormal signal at the parenchymal margin of
the brainstem.
Cerebrospinal fluid biochemistry: glucose 2.
09mmol/L, protein and chloride normal
.
Serum neuronal-specific enolase (NSE): 16.
59 μg/L (normal< 16.
3 g/L).
<b13>

Figure 1: FLAIR shows high symmetry in the front and side of the brainstem, similar to a "traitor head"

Figure 2: DWI shows high symmetry in front and lateral brainstem with limited diffusion

Figure 3: ADC shows low symmetry in front and side of the brainstem with limited diffusion

Figure 4: Enhancement shows no significant enhancement anterior or lateral to the brainstem

Fig.
5: Chest CT showed lung cancer in the upper lobe of the left lung (description: increased texture and disorder of both lungs, soft tissue mass shadow can be seen in the posterior part of the tip of the upper lobe of the left lung, the size is about 3.
3cm×1.
9cm, the boundary is not clear, shallow lobes and small burrs can be seen, the side traction is obvious, the lesion is mild-moderate uneven strengthening, and multiple small nodules are
seen on the left oblique fissure.
Conclusion: The posterior part of the apical segment of the upper lobe of the left lung is occupied, considering peripheral lung cancer, and the left oblique fissure has multiple small nodules, except for metastasis)

Fig.
6: The initial pressure of cerebrospinal fluid is 300mmH20, and the cytology of cerebrospinal fluid shows that white blood cells are 8/mm3 (1 is each monocyte
of lymphocytes.
2 for tumor cells: large cell volume, large nucleus, coarse nuclear chromatin, obvious nucleoli, cytoplasmic strong basophil)

Diagnosis: meningeal cancer, lung cancer with meningeal metastases
.

discuss

1 Perivascular space and tumor metastasis

The perivascular space, the Virchow-Robin cavity (VRS), is a normal anatomical structure within the nervous system with certain physiological and immune functions
.

More than a century ago, German pathologist R.
Virchow and French biologist and histologist C.
P.
Robin proposed the concept, which was later named Virchow-Robin cavity (VRS), also known as the perivascular lymphatic space
.

Figure 7: Perivascular space pattern diagram

2Diagnose the problem

Lung cancer is one of the most common malignant tumors in China, and its incidence and mortality rate are increasing year by year
.
The main reason for poor prognosis in lung cancer patients is local recurrence or distant metastases, of which the detection rate of meningeal metastases (leptomeningeal metastasis, LM) is about 5%.

The prognosis for patients with meningeal metastases of lung cancer is extremely poor, with a median survival of only 4 to 6 weeks
in untreated patients.
LM, also known as meningeal carcinoma, refers to a serious lesion
in which malignant tumor cells directly invade the meninges through hematogenous metastasis, lymphatic system metastasis, and cerebrospinal fluid implantation to meninges or adjacent tumors.

The patient has a clear history of lung cancer, and the cerebrospinal fluid glucose is 2.
09mmol/L, which is lower
than the normal value.
Elevated serum neuron-specific enolase (NSE) is seen in lung cancer and brain injury, and tumor cells are found in cerebrospinal fluid, which confirms meningeal metastases
.

3 Imaging characteristics and possible mechanisms

MRI of the affected head is mainly manifested as linear abnormal signals around the brainstem, FLAIR and T2WI show high intensity, DWI is limited, pons and midbrain are mainly affected, the image is called "traitor head sign", and no abnormalities
are seen in other brain areas.

The distribution site and signal characteristics are relatively specific, similar abnormal signals can be seen in neurosyphilis, tuberculosis and sarcoidosis, but its pathology is that the granulomatous lesions are significantly intensified, and the disease is obviously inconsistent
.

Lung cancer brain metastasis, from the imaging diagnostic criteria of meningeal strengthening, the meninges of the disease are not strengthened, but tumor cells are found from the cerebrospinal fluid, consistent with meningeal metastases
.

Reasons for not hardening:

(1) Studies have found that tumor cells can not be strengthened when tumor cells float in the subarachnoid space and do not form a tumor nest, and the tumor nest formation will be strengthened
when the lesion progresses.

(2) The pathological study of cortical linear metastasis cases found that cortical metastasis is mostly intravascular metastasis, tumor cells enter VRS, lesion DWI diffusion is limited, glial boundary membrane is not broken, and the blood-brain barrier is not damaged, so there is no strengthening
.

The perivascular space is the main structure of brain interstitial fluid drainage, which is equivalent to the lymphatic system of the human body, and perivascular intervascular tumor cells can flow to the interstitial space on the brain surface and then enter the subarachnoid space
.

The cerebrocadesarel vascular supply system is a vertebrobasilar artery system, with comb-like straight and few branches of perforatorial vessels, and its corresponding perivascular space is relatively smooth
relative to the cortex.

At the same time, the brainstem emits many cranial nerves, and the pericranial nerve space communicates with the perivascular space, which is the main channel
for intracranial interstitial fluid drainage.

It is speculated that when tumor cells in the small perforage terminal of the brainstem enter the space around the blood vessels, they soon enter the interstitial fluid space on the brain surface, resulting in interstitial fluid drainage blockage and expansion, which is manifested as linear or membranous effusion on the surface of the brainstem, so that the cerebral cortex is damaged, such as psychiatric symptoms
.

Due to the large protein components in the interstitial fluid in the perivascular space, it is manifested as long T2, high FLAIR limit, and limited
DWI.
The blood-brain barrier is not broken, so there is no reinforcement
.

4Clinical and imaging

The imaging lesions of this patient are in the brainstem, but the main clinical symptoms are episodic loss of consciousness, unresponsive to aphasia, accompanied by urinary incontinence, which may be seizures
.

After the recovery of consciousness, psychiatric symptoms appeared, and the family found that the patient's voice was significantly larger than before, the speech was confused, and the names of some family members were difficult to remember, accompanied by unstable walking, which was localized to the cerebral cortex for cognitive function decline, psychiatric symptoms, and supported lesions located in the interstitial space on the brain surface, and lymphoid encephalopathy
.

The absence of brainstem cranial nerve involvement indicates that the subarachnoid space around the affected brainstem is unobstructed and no cranial nerve roots
are involved.

5 Epilogue

"Traitor head sign" - semi-annular FLAIR high-intensity foci around the brainstem, currently mainly seen in lung cancer meningeal metastasis, speculated that its mechanism is mainly non-reversible lymphoedema secondary to interstitial fluid space tumor cell metastasis on the surface of the brainstem, and the prognosis is poor
.
The image of the characteristics of the "traitor's head sign" makes us unforgettable, and the diagnosis is quickly killed
.

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