A 3 years old child’s parents noticed a small swelling on the head at 2 months of age. the swelling increased gradually in size for a year then spontaneously decreased over a year. Following trivial fall, the swelling increased dramatically 3 days prior to presentation. He was otherwise normal.

On examination, the swelling was firm, smooth and pulsatile. No change related to posture or crying was seen.

A CTA was done.

CTA, SSD and MIP images showing the right parietal swelling (hematoma) with a small AVM posteriorly, fed by branches of right superficial temporal artery. the feeders are elevated by the swelling. Also seen are a couple of phleboliths.

The AVM per-se was not filling a lot with contrast, probably partially thrombosed.

The baby was given antiinflammatory drugs and called for AVM excision after the hematoma resolved subsequently.

43 years old male patient had a ruptured Acomm artery aneurysm and came for coiling after 1.5 months.

the first coil was successfully placed, however there was stretching of the second coil hence it was removed along with the microcatheter.

Subsequently a fresh catheter was intriduced over a microwire. During the manipulation, contrast leakage was noted from the supraclinoid ICA

LICA injection AP and Lat views showing  contrast extravasation from terminal ICA. Note that the micocatheter has been pulled down now

Fortunately, the extravasation stopped spontaneously and rather quickly.

LICA injection after 3 minute of perforation, AP and Lat views, showing normal arteries with no e/o leakage anymore

Further coiling was abandoned. Intracranial blood circulation was normal and patient was hemodynamically stable.

DynaCT at end of procedure showing diffuse SAH. Dense contrast is seen in ambient cistern

NCCT head done next morning, patient still intubated, showing diffuse SAH, IVH, e/o residual contrast and significant hydrocephalus

NCCT head, post EVD, which was done immediately after seeing the preceding scan; patient was hemodynamically stable throughout

On day 3, patient was extubated and had bilateral lower limb paresis (2/5) as well as left upper limb paresis (4/5). He was irritable with intermittent comprehension and response. Gradually, over a period of 6-7 days, his neurology improved, however he still had significant left lower limb weakness nad the irritability persisted.

NCCT on day 7 showing near complete resolution of hemorrhage, hydrocephalus still persists

MRI on day 7, done as no focal lesion was seen on the preceding CT, shows hydrocephalus, left temporal region hematoma and underlying parenchymal signal change, but no other focal lesions.

EVD drainage was done for two days, during which time , he improved significantly.

After a total of 2 weeks, he was discharged in a stable condition, with only mild residual weakness in left ankle and slight behavioral change but otherwise with good mental score.

This middle aged patient was admitted with history of sudden onset weakness of the left hand about 8-10 days ago. There was past history of transient numbness of left upper limb lasting for 1-2mins about one month ago. MRI brain revealed multiple acute right fronto-parietal infarcts the arranged as a ‘string of pearls’.

DWI images on day of stroke showing multiple acute infarcts in right frontal and parietal region involving both the cortex as well as the subcortical white matter and centrum semiovale

MRA revealed ~ 70% stenosis of proximal RICA.

CE-MRA MIP image showing signal loss and stenosis at right carotid bulb (hand-marked arrow); remaining neck vessels are normal

Carotid DSA was planned with the aim for revascularization.

Right common carotid artery injection revealed a plaque with filling defect in the RICA just beyond the bifurcation with a meniscus sign (suggestive of fresh intraluminal thrombus), causing a 70% stenosis.

RCCA injection lateral view showing the thrombus and stenosis of the carotid bulb

As there was a fresh intraluminal thrombus, revascularization was deferred in view of a high risk of distal embolization. The patient was kept on medications  (heparin for a week, clopidogrel, aspirin, atorvastatin)for a period of 2 weeks.

She had gradual and continuous improvement in power and came for DSA after a month.

DSA this time showed resolution of the thrombus and now only a mild smooth stenosis remained.

Follow up DSA after a month showing mild stenosis with no evidence of thrombus

She has been doing well till now and had near complete recovery of power with no further ischemic neurological events

Hello friends.

Coronal T2WI

Axial GRE showing left pontine cavernoma

Axial T2WI showing left inferior olivary nucleus hypertrophy and altered signal

Sagittal T2WI

Hypertrophic olivary degeneration is a form of transsynaptic degeneration. It represents the end result of a lesion that damages the neuronal connections between the dentate nucleus of the cerebellum, the red nucleus, and the inferior olivary nucleus: the dentatorubral-olivary pathway (1,2). It is considered a unique type of degeneration because it is associated with enlargement, rather than atrophy, of the affected structure—the inferior olivary neurons (3).

The affected circuit connects the dentate nucleus of the cerebellum, the contralateral red nucleus, and the ipsilateral inferior olivary nucleus. The dentate nucleus and the contralateral red nucleus are connected by the superior cerebellar peduncle (dentatorubral tract), with fibers crossing in the decussation of the peduncle at the lower midbrain. This tract is part of a reflex arc that controls fine voluntary movements. The red nucleus and the ipsilateral inferior olivary nucleus are connected by the central tegmental tract. These dentatorubral-olivary connections were described by Guillain and Mollaret (2) in 1931 as the anatomic connections related to palatal myoclonus, which is a common clinical association, and this pathway is thus referred to as the “Guillain-Mollaret triangle.”

In 1935, Trelles (4) reported that isolated lesions of the inferior cerebellar peduncle never cause palatal myoclonus, since anatomically there are no direct connections between the inferior olivary nucleus and the contralateral dentate nucleus. Fibers from the inferior olivary nucleus instead project first to the cerebellar cortex (olivocerebellar tracts) and then to the dentate nucleus. He described these connections as the dentatorubral-olivary pathway (5).

Since hypertrophic olivary degeneration occurs owing to interruption of the pathways composing the Guillain-Mollaret triangle, it most commonly occurs following development of focal lesions of the brainstem. Focal brainstem insults that may lead to pathway interruption include ischemic infarction, demyelination, and hemorrhage, the latter often related to hypertensive disease or diffuse axonal injury following severe head trauma (6–8). Olivary hypertrophy is not seen immediately after the brainstem insult but typically appears in a delayed fashion, usually within 4–6 months. The pathologic process persists and is frequently visible after 10 months. Clinical symptoms such as abnormal movement rarely improve. Although olivary hypertrophy typically resolves in 10–16 months, olivary hyperintensity on T2-weighted images may persist for years after resolution of the hypertrophy (9,10).

The specific relationship between the primary lesion and the development of olivary degeneration results in the production of one of three patterns that are easily understood by reviewing a diagram of the involved neuronal pathway (Fig 3). When the primary lesion is limited to the central tegmental tract, olivary hypertrophy is ipsilateral, since only ipsilateral fibers are affected. When the primary lesion is in the dentate nucleus or in the superior cerebellar peduncle, olivary degeneration is contralateral; and when the lesion involves both the central tegmental tract and the superior cerebellar peduncle, olivary hypertrophy is bilateral. The patient in this case has only unilateral olivary hypertrophy, despite having some signal intensity abnormality in the superior cerebellar peduncle—hypointensity in the tegmental area extends into the left superior cerebellar peduncle.Transneuronal degeneration occurs only from a lesion that results in disconnection of the pathway. Abnormal changes in signal intensity on MR images do not necessarily define the severity of the injury. In this case, the hypointensity on T2-weighted images in the superior cerebellar peduncle does not represent disruption of fibers; instead, it most likely represents staining of adjacent tissues by blood products at the periphery of the pontine hemorrhage.

Olivary enlargement corresponds pathologically to an unusual vacuolar degeneration of cytoplasm that results in enlargement related in part to an increased number of astrocytes. Vacuolar degeneration of the cytoplasm occurs at 6–15 months, and gliosis follows 15–20 months after the onset of the primary lesion (10).

Clinical findings associated with olivary hypertrophy include the signature syndrome: palatal myoclonus, or cyclic jerk of the soft palate, and also dentatorubral tremor and ocular myoclonus. Palatal myoclonus, a form of “segmental” myoclonus, is a rhythmic involuntary movement of the oropharynx, similar to the accessory respiratory reflex seen in fish. The typical tremor consists of muscle contractions at one to three cycles per second and is not affected by voluntary controls. Severe myoclonus may also affect the cervical muscles and the diaphragm. The anatomic correlation is the central tegmental tract, which has several connections to the nucleus ambiguus—the vagus nerve is involved in control of palatal movement (5). A lesion in the dentatorubral pathway may cause the patient to lose inhibitory control transmitted through these structures, and palatal myoclonus or other types of abnormal movement may develop. Palatal myoclonus usually develops 10–11 months after the primary lesion, although palatal myoclonus does not always accompany olivary hypertrophy, as is evidenced in the test case (12–14). It should be noted that the clinical pattern of palatal myoclonus also may be seen with focal spinal cord insults (15).

Considering the differential diagnosis of the medullary lesion, high intensity in the anterolateral part of the medulla is not a specific imaging finding. It may be seen with a wide variety of pathologic processes, including infarction; demyelination related to multiple sclerosis; tumor (eg, astrocytoma, metastasis, and lymphoma); and infectious and other inflammatory processes such as tuberculosis, acquired immunodeficiency syndrome, sarcoidosis, and rhombencephalitis. However, if the lesion is strictly limited to one or both inferior olivary nuclei, with sparing of the surrounding medullary tissues, and particularly if there is associated focal olivary enlargement, hypertrophic olivary degeneration should be strongly suggested.

Most neoplasms and infectious processes would be expected to demonstrate intense enhancement. Most infarctions of the medulla are related to disease of the posteroinferior cerebellar artery and are posterolateral in location, or they are related to perforating branches from anterior spinal or vertebral arteries and have a paramedial location. Clinically, acute infarction of the inferior olivary nucleus would likely cause ataxia. Therefore, the diagnosis of infarction is unlikely. Wallerian degeneration, adrenoleukodystrophy, and amyotrophic lateral sclerosis also may demonstrate anterior medullary high intensity on T2-weighted images; however, in these cases, lesions generally are limited to the corticospinal tract and not to the inferior olivary nucleus.

The most important clue to the diagnosis is the association of a remote lesion. The presence of an olivary lesion in association with another lesion in the contralateral cerebellar dentate nucleus, the contralateral superior cerebellar peduncle, the ipsilateral dorsomedial red nucleus, or the ipsilateral pontine tegmentum (as in the test case) makes any diagnosis other than hypertrophic olivary degeneration highly unlikely.

Several authors (16,17) have noted that Wernicke-Korsakoff syndrome may be associated with pathologic change in the inferior olivary nucleus. Again, it is the combination of the inciting lesion in the proper anatomic location, and the observers' knowledge of the association, that permits the diagnosis to be made. MR imaging, due to its exquisite contrast sensitivity and lack of bone artifact in the low posterior fossa, is the most sensitive and specific tool for the diagnosis of olivary hypertrophic changes.

Diagram showing the anatomy involved

1, Thalamus; 2, red nucleus;3, superior cerebellar peduncle; 4, central tegmental tract; 5, dentate nucleus; 6, olivary nucleus; 7, cerebellum.

References

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He had thick hypertrophied soft palate with persistent myoclonus.......video will be posted next....