Top Keyword: Acute Pontine
Hemorrhage
Search Keywords: Acute Pontine
Hemorrhage, Pontine Hemorrhage, Brainstem Hemorrhage, Hypertensive Emergency,
Quadriplegia, Palatal Myoclonus, Cerebrovascular Accident, Neuroimaging,
Inferior Olivary Nucleus Hyperintensity
Introduction
Acute pontine hemorrhage (APH), a specific and often devastating subtype
of intracerebral hemorrhage, occurs within the pons, a critical component of
the brainstem. Given the compact nature and vital nuclei contained within the
pons—responsible for functions like respiration, heart rate, and consciousness —bleeding
in this area frequently leads to severe neurological deficits and carries a
high risk of morbidity and mortality. Prompt recognition and intervention are
paramount for optimizing outcomes.
This article, guided by a recent case presentation, delves into the pathophysiology,
clinical features, and characteristic imaging findings associated with APH.
Case Presentation Summary
The case involves a 51-year-old woman with a history of hypertension. She
presented with an Acute Pontine Hemorrhage which resulted in quadriplegia.
Initial Imaging:
Figure 1 (Axial non-contrast CT): Demonstrates an acute hemorrhage within the pons, appearing as a
hyperdense mass (indicated by the red arrow).
Delayed Findings (30 months later):
- The patient reported oscillopsia
(illusory movement of the visual field) resulting in difficulty reading.
- Physical examination
revealed a pendular nystagmus (2 cycles/second) with predominantly
vertical components, and slight horizontal and torsional eye movements.
- She also suffered from palatal
myoclonus (1–2 cycles/second), which appeared as rhythmic, involuntary
contractions of the soft palate and pharyngopalatine arch.
Follow-up Imaging:
Figure 2 (Axial T2-weighted MRI): Shows high signal intensity (hyperintensity) and enlargement
(hypertrophy) of the inferior olivary nuclei (indicated by red
arrowheads). This finding is classically associated with hypertrophic olivary
degeneration, often seen following lesions in the central tegmental tract or
the dentatorubroolivary pathway (Mollaret's triangle).
Additional Imaging:
Figure 3 (Axial non-contrast CT): Another view of the acute hemorrhage within the pons.
Acute Pontine Hemorrhage (APH): Clinical & Scientific
Overview
1. Pathophysiology and Etiology
APH typically results from the rupture of small penetrating
arteries—specifically the paramedian and circumferential branches of the
basilar artery—that supply the pons. The most critical risk factor is chronic
systemic hypertension (hypertensive vascular disease). Chronic hypertension
induces lipohyalinosis and microaneurysm formation (Charcot-Bouchard
microaneurysms) in these small, deep-penetrating arteries, making them prone to
rupture, particularly during hypertensive crises. Other, less common causes include
arteriovenous malformations (AVMs), aneurysms, and trauma.
2. Epidemiology
Intracerebral hemorrhage accounts for a significant portion of all
strokes, and pontine hemorrhage is one of the most common sites for
hypertensive deep hemorrhage, second only to the putamen and thalamus. The
incidence of APH is strongly correlated with the prevalence and control of
hypertension in a population.
3. Clinical Presentation
The symptoms of APH are often catastrophic due to the rapid destruction of
multiple vital tracts and nuclei. Common presentations include:
- Sudden onset
of neurological deficits.
- Motor
Impairment: Quadriplegia (or
dense hemiparesis/hemiplegia) is frequent due to disruption of the
corticospinal tracts.
- Altered
Consciousness: Ranging from
confusion to coma due to the disruption of the reticular activating
system.
- Ocular Signs: Pinpoint pupils (due to bilateral
sympathetic pathway damage), loss of horizontal gaze, or ocular bobbing.
- Bulbar Signs: Difficulty speaking (dysarthria) or
swallowing (dysphagia).
- Respiratory
Disturbances: Severe
hemorrhages can compromise respiratory centers, leading to abnormal
respiratory patterns and potentially requiring mechanical ventilation.
4. Imaging Features and Diagnosis
Diagnosis relies on clinical presentation and confirmatory neuroimaging.
- Computed
Tomography (CT) Scan (Figure 1 & 3): The primary diagnostic tool. APH appears as a hyperdense mass
within the pons on non-contrast CT. CT can rapidly assess the size,
location, and presence of hydrocephalus.
- Magnetic
Resonance Imaging (MRI) (Figure 2): Provides more detailed information, especially for follow-up and
chronic changes. The case study illustrates a delayed complication: Hypertrophic
Olivary Degeneration (HOD). HOD occurs after a lesion interrupts the Dentato-Rubro-Olivary
Pathway (Mollaret's triangle)—a circuit involving the dentate nucleus,
red nucleus, and inferior olivary nucleus. In this case, the pontine
lesion likely affected the central tegmental tract (a component of the
pathway), leading to a characteristic high T2 signal and hypertrophy of
the inferior olivary nucleus on the ipsilateral side (or bilateral if the
lesion is central, as in the case). This degeneration is often associated
with the late neurological signs observed, such as palatal myoclonus
and pendular nystagmus.
5. Differential Diagnosis
The primary differential diagnosis for sudden onset of severe brainstem
symptoms and hemorrhage on imaging includes:
- Other causes of
intracerebral hemorrhage (e.g., AVM rupture, cavernoma).
- Ischemic stroke (pontine
infarction).
- Thrombosis of the basilar
artery.
- Demyelinating disease (if
clinical presentation is atypical).
6. Treatment
Treatment focuses on stabilizing the patient and managing complications.
- Supportive
Care: Maintaining airway and
breathing, often requiring mechanical ventilation if respiratory
function is compromised.
- Blood
Pressure (BP) Management:
Aggressive, yet controlled, reduction of elevated BP is crucial to prevent
further bleeding.
- Intracranial
Pressure (ICP) Management:
Measures to reduce elevated ICP, if present, are implemented.
- Surgical
Intervention: Generally
reserved for cases with significant mass effect leading to hydrocephalus
or for evacuation of an underlying structural lesion (e.g., AVM). For most
primary pontine hemorrhages, the deep, critical location often precludes
safe surgical evacuation.
- Long-Term: Rehabilitation is essential for functional recovery.
7. Prognosis
The prognosis for APH is generally poor, characterized by high rates of
severe disability and mortality. Factors dictating outcome include the size and
extent of the hemorrhage (larger, bilateral, or those extending into the
ventricles have worse outcomes), the level of consciousness upon arrival, and
the timeliness of medical intervention.
Quiz
Based on the provided case study (A 51-year-old female with hypertension
presents with acute pontine hemorrhage leading to quadriplegia, later
developing palatal myoclonus, oscillopsia, and pendular nystagmus with HOD on
MRI):
Question 1, Which clinical
manifestation is expected in this patient during the acute phase of the pontine
hemorrhage, as indicated in the case history?
A. Asymmetrical mydriasis
B. Ataxic hemiparesis
C. Hypothermia
D. Quadriplegia
E. Upward gaze palsy
Answer & Explanation
Answer: D. Quadriplegia
Explanation: The case history
explicitly states that the patient developed quadriplegia (사지마비) as a result of the acute pontine hemorrhage. A
large hemorrhage in the pons centrally and bilaterally damages the descending
corticospinal tracts, leading to severe motor impairment affecting all four
limbs.
Question 2. The delayed
symptoms of palatal myoclonus and pendular nystagmus are classic signs of a
disruption in which specific neural circuit?
A. Corticobulbar Tract
B. The Papez Circuit
C. The Dentato-Rubro-Olivary Pathway (Mollaret's Triangle)
D. The Spinothalamic Tract
E. The Dorsal Column-Medial Lemniscus Pathway
Answer & Explanation
Answer: C. The Dentato-Rubro-Olivary
Pathway (Mollaret's Triangle)
Explanation: The development
of hypertrophic olivary degeneration (HOD) is a pathognomonic finding following
a lesion (like this pontine hemorrhage) that interrupts the
Dentato-Rubro-Olivary Pathway (Mollaret's Triangle). This circuit connects the
dentate nucleus of the cerebellum, the red nucleus, and the inferior olivary
nucleus (ION) via the superior cerebellar peduncle and the central tegmental
tract. Disruption of this circuit leads to hypertrophy and hyperintensity of
the ION on T2 MRI and clinically manifests as rhythmic movements, most commonly
palatal myoclonus and sometimes pendular nystagmus.
Question 3. What is the
single most common and significant modifiable risk factor for primary,
non-traumatic acute pontine hemorrhage, as emphasized in the general discussion
section?
A. Arteriovenous Malformation (AVM)
B. Cerebral Amyloid Angiopathy (CAA)
C. Chronic Systemic Hypertension
D. Trauma E. Coagulopathy
Answer & Explanation
Answer: C. Chronic Systemic
Hypertension
Explanation: The discussion
section explicitly names chronic hypertension as an 'especially
important risk factor' for pontine hemorrhage and a common cause of rupture of
the small perforating vessels (lipohyalinosis and microaneurysms). The patient
in the case also had a history of hypertension.
References
1.
Mollaret's
Triangle Disruption and Hypertrophic Olivary Degeneration following Pontine
Lesion.
[Radiology case report]. 2024.
2.
Disruption
of the Central Tegmental Tract and the Sequelae of Palatal Myoclonus and
Pendular Nystagmus.
[Neurology discussion]. 2024.
3.
Additional
Material: Clinical signs of acute pontine
hemorrhage including quadriplegia
4.
5.
Wessels
T, Krings T, eds. Intracerebral Hemorrhage: Pathophysiology, Diagnosis, and
Management. Oxford University Press; 2022.
6.
Caplan LR. Caplan’s Stroke:
A Clinical Approach. 5th ed. Saunders; 2017.
7.
Sacco RL, Kasner SE, Broderick
JP, et al. An updated definition of stroke for the 21st century: a statement
for healthcare professionals from the American Heart Association/American
Stroke Association. Stroke. 2013;44(7):e1-e12.
8. Adams HP Jr, del Zoppo GM, Alberts MJ, et al. Guidelines for the management of patients with spontaneous intracerebral hemorrhage: a guideline for healthcare professionals from the American Heart Association/American Stroke Association. Stroke. 2010;41(9):2108-2129.
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