Approach to differentiating lesions (cerebellum): Clinical sciences

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Introduction0:00–0:31

The cerebellum, which is the major control center for the coordination of voluntary movements and balance is connected via multiple pathways to the cerebrum brainstem and the spinal cord conditions that can affect the cerebellum.
And these connecting pathways can be subdivided into acute subacute and chronic cerebellar lesions. Now, if your patient presents with chief concerns, suggestive of a cerebellar lesion, first perform an ABCD E assessment to determine if they are stable or unstable, if unstable, stabilize the airway breathing and circulation.

Unstable Patient0:31–1:10

In some cases, you might even have to intubate the patient and start mechanical ventilation. Next, obtain IV access and consider starting IV fluids.
Finally put your patient on continuous vital sign monitoring including heart rate, BP and pulse oximetry as well as cardiac telemetry.
All right, let's go back to the ABCD E assessment and focus on stable patients. In this case, obtain a focused history and physical examination.

Stable Patient1:10–4:41

These patients will report a loss of coordination such as difficulty walking, keeping balance, sitting up straight or using their arms to pick up objects.
They might also report a room spinning, dizziness with nausea and vomiting, difficulty focusing their vision slurred speech or difficulty with swallowing.
On the exam, you will find limb truncal or gait ataxia, which refers to the loss of coordination of voluntary movement, limb ataxia, which is predominantly seen with cerebellar hemispheric lesions is associated with dysmetria on finger to nose or heel to shin testing.
For example, on the finger to nose test, the patient might point past the target as they are unable to judge the distance properly known as past pointing.
Another example of limb ataxia is dysdiadochokinesia on rapid alternating movements, which can be tested by asking the patient to alternate supinating and pronating their arms on the flip side.
Truncal ataxia, which is most prominent with cerebellar vermis lesions is associated with severe truncal swaying when the patient is trying to sit or stand up straight or titubation, which is an anterior posterior rhythmic tremor of the head or upper trunk.
Finally, gait ataxia is characterized by a wide based unsteady gait with an irregular rhythm and inconsistent stride length.
Gait ataxia is especially obvious during tandem testing, perform this test by asking the patient to walk with the heel of 1 ft, touching the toes of the other foot with each step as if they were walking on a tightrope.
In addition to ataxia, you might find abnormal eye movements due to lesions of the flocculonodular lobe of the cerebellum.
Some important findings include nystagmus as well as impaired smooth pursuit and SADs. Nystagmus is rhythmic, rapid eye movements with a fast phase in one direction and a slow phase in the opposite direction.
Examples of pathologic nystagmus, consistent with a central nervous system lesion include vertical nystagmus and direction changing nystagmus.
Impaired smooth pursuit is the inability to smoothly follow a moving object. While impaired ses refers to the inability to rapidly change the fixation of vision from one stationary object to another.
There might be abnormal speech such as dysarthria or scanning speech, which is an abnormal speech pattern that is slow with words broken up into syllables in different intonations.
Lastly, you might find an intentional tremor, a side to side tremor of the arm that worsens upon reaching the intended target or a postural tremor while holding the arms in position.
With these findings, consider a cerebellar lesion. So your next step is to assess the time course of symptoms.

Cerebellar stroke4:41–6:10

If the onset of symptoms is acute, assess whether the symptoms are unilateral or bilateral with unilateral symptoms. Consider cerebellar stroke as the underlying cause and obtain imaging of the brain with CT or MRI.
If there is a stroke involving the superior aspect of the cerebellum and the superior cerebellar peduncle diagnose a superior cerebellar artery stroke.
If you identify a stroke in the anterior inferior cerebellum and middle cerebellar peduncle diagnose an anterior inferior cerebellar artery stroke.
Finally, if the stroke is in the posterior inferior cerebellum and inferior cerebellar peduncle diagnose a posterior inferior cerebellar artery stroke.
Here's a clinical pearl, the posterior inferior cerebellar artery, also supplies the lateral medulla. So the patient might present with lateral medullary syndrome, also known as Wallenberg Syndrome.
In addition to ataxia, these patients will have dysphasia, hoarseness, decreased pain and temperature sensation in the ipsilateral face and contralateral body and ipsilateral Horner syndrome.

Acute cerebellitis6:10–7:09

Next, let's discuss a patient with acute onset bilateral symptoms in this case, consider acute cerebellitis, which is more commonly seen in Children.
Various infectious agents are associated with this condition, particularly varicella zoster virus, Epstein barr virus, Coxsackievirus herpes simplex virus and mycoplasma pneumoniae.
To confirm your diagnosis, obtain a brain MRI, the patient will report nausea and vomiting, headache, confusion, recent illness and possibly persistent fever on the exam, you will find altered mental status and ataxia of the limbs, trunk and gait.
While the MRI will show abnormally increased signal and edema of the cerebellum. With these findings diagnose acute cerebellitis.

Spinocerebellar ataxia7:09–8:55

All right. Let's move on to patients with a subacute or chronic progression of symptoms.
In this case, your first step is to assess for a family history of similar symptoms. If present, consider genetic syndromes such as spinocerebellar ataxia three and Friedreich ataxia.
First, let's focus on spinal cerebellar ataxia three, which is the most common autosomal dominant ataxia in these individuals.
History reveals first degree relatives with the same symptoms which started in adolescence or early adulthood. In addition to loss of coordination, patients report progressive weakness and stiffness in the legs and sustained muscle tightening or twisting of different body parts on the exam.
You will notice truncal limb and gait ataxia. There is also eyelid retraction with bulging eyes, impaired upward gaze and horizontal and vertical nystagmus.
You will also find parkinsonism, specifically rigidity and bradykinesia dystonia, which refers to sustained muscle contractions, especially of the neck or limbs and distal motor weakness.
With these findings consider spinocerebellar ataxia. So obtain a sample for genetic testing if genetic testing reveals cag trinucleotide repeat expansion on the ataxin three gene diagnose spinocerebellar ataxia three.
Ok. Now, let's discuss Friedrich ataxia, which is the most common form of inherited ataxia.

Friedreich ataxia8:55–10:08

This time, the patient will report symptom onset during childhood or adolescence. In addition to loss of coordination, the patient will report progressive gait difficulties, numbness and possibly weakness.
They might also report slurred speech or difficulty swallowing while their history might reveal chronic conditions like cardiomyopathy or diabetes.
In addition to truncal limb and gait ataxia, the exam will show loss of proprioceptive and vibratory sensation and a positive Romberg test which indicates impaired proprioception.
You might also find limb weakness and skeletal deformities like scoliosis, pes cavus and Hammertoes. With these findings consider Friedreich ataxia and obtain genetic testing.
If you identify expanded ga a trinucleotide repeats on the Frataxin gene diagnose Friedreich ataxia. Next, let's discuss patients with subacute or chronic progression and no family history of similar symptoms.

Alcoholic cerebellar degeneration10:08–10:46

In this case, assess for chronic alcohol use if present, consider alcoholic cerebellar degeneration and obtain a ct or MRI of the brain.
If imaging shows cerebellar vermian atrophy, diagnose alcoholic cerebellar degeneration because the vermis is predominantly affected in this condition.
The truncal and gait ataxia are much more prominent than limb ataxia. On the flip side, if there is no history of chronic alcohol use, assess the underlying cause with further investigation of the history and physical exam.

Chiari type 1 malformation10:46–12:33

In this case, you should think of chiari type one malformation, multiple system atrophy, particularly the cerebellar type and paraneoplastic cerebellar degeneration.
First, let's focus on chiari type one malformation, which is associated with posterior headaches or neck pain that worsens with valsalva maneuvers such as coughing, sneezing or straining for a bowel movement.
Patients might also report progressive weakness and sensory loss particularly in the arms. They might also have slurred speech, hoarseness or trouble swallowing on physical exam.
You will find truncal ataxia which is more prominent than limb ataxia. Also, you might notice downward beating nystagmus and cranial neuropathies, particularly with cranial nerves in the medulla, you might detect spasticity and weakness as well as cape like distribution of sensory loss over the shoulders, chest and arms.
With these findings consider a chiari type one malformation and obtain an MRI of the brain and cervical spine. Imaging usually shows downward displacement of the cerebellar tonsils below the level of the foramen magnum.
Frequently a chiari type one malformation is associated with a syrinx which is a fluid filled cyst in the spine. If you see these findings, that's a chiari type one malformation.
Ok. Now, let's look at multiple system atrophy, specifically the cerebellar type of this condition.

Multiple system atrophy12:33–14:00

In this case, the patient reports multiple different symptoms due to autonomic dysfunction, including dizziness upon standing and urinary or stool retention or incontinence.
Also, there is a slowing of movements with or without tremors. Additionally, their partner might report that the patient makes a high pitched sound while breathing during sleep on physical exam.
Vital signs are consistent with orthostatic hypotension. Also, you will notice truncal limb and gait ataxia as well as scanning dysarthria and hoarseness.
Finally, the exam will reveal signs of parkinsonism like rigidity and bradykinesia possibly with tremors. In some cases, you might find stridor from vocal cord dysfunction.
In this case, consider multiple system atrophy, particularly the cerebellar type and obtain a brain MRI if the brain MRI shows atrophy of the cerebellum and pons and a hot cross bun sign in the pons, which is consistent with atrophy of pontocerebellar fibers, diagnosed the neurodegenerative condition called multiple system atrophy cerebellar type.

Paraneoplastic cerebellar degeneration14:00–14:48

Finally, let's discuss paraneoplastic cerebellar degeneration, which is associated with nonspecific symptoms such as dizziness, nausea and vomiting as well as slurred speech and trouble swallowing.
Patients also report a history of cancer specifically of the lung, breast gynecologic organs or hodgkin lymphoma. If the exam reveals ataxia of the trunk limb and gait, consider paraneoplastic cerebellar degeneration.
In this case, obtain paraneoplastic panels of the serum and cerebrospinal fluid. If you detect anti yo anti who or anti tr antibodies, diagnose paraneoplastic cerebellar degeneration.
All right. As a quick recap, cerebellar signs include ataxia, abnormal eye movements and speech and intention or postural tremors.

Review14:48–15:38

Acute and unilateral symptoms should make you think of stroke while acute and bilateral symptoms should make you consider acute cerebellitis in cases of subacute or chronic symptom onset.
Consider genetic syndromes such as spinocerebellar ataxia three and Friedreich ataxia. On the flip side.
If there is no family history, consider alcoholic cerebellar degeneration, chiari type one malformation, multiple system atrophy or paraneoplastic cerebellar degeneration.