Case: 14-year-old Girl with Dizziness

00:01 So let's dive into each of these.

00:02 But first, let's go over a case and understand why it's important to understand cerebellar circuitry.

00:09 This is a 14-year-old girl who presents to the emergency department with several month history of headaches, nausea, and vomiting.

00:15 Her family reports that she's had headaches for several years, that began to increase in frequency and severity about three months ago.

00:24 Now, she has early morning headaches, early morning vomiting or emesis.

00:28 Her exam reveals a slight sway to the right, when she's sitting, and consistent truncal ataxia.

00:35 Impaired finger-to-nose finger bilaterally and the inability to perform heel-toe walking all cerebellar signs.

00:42 MRI is performed and reveals a lesion in the posterior fossa.

00:46 And you can see that in the figure here a large lesion in the midline of the cerebellum.

00:51 She undergoes surgery for gross total resection and pathology returns a medulloblastoma.

00:56 That's one of those childhood brain tumors that can affect the midline of the cerebellum.

01:03 Postoperatively, the patient's initially appears to be doing well without headache or new symptoms until post-op day two, when she's found to be awake, and purposeful but apathetic.

01:14 She's not interested in doing anything.

01:16 She's lacks motivation.

01:18 She would not produce speech and refuse to eat.

01:20 So she is not able to talk and is not eating.

01:23 She's incontinent of urine.

01:25 She has emotional ability, and exam shows prominent cerebellar dysmetria, dysdiadochokinesia, which is problem with rapid alternating movements, no papilledema or other cortical signs.

01:37 So what's going on with this patient? Does this sound like drug-induced cerebellar dysfunction, cerebellar mutism, obstructive hydrocephalus, or a brainstem stroke? Well, there are a few things we can take away from this case.

01:50 Whenever we're evaluating a problem in the brain, that timeline of onset is critical.

01:55 And this sounds like a subacute onset condition initially, that was consistent with a growing tumor.

02:02 We can look at the patient's description of we have how she initially presented? And there were prominent cerebellar findings, which pointed us to the need to get the MRI.

02:11 Now, after surgery, something different is going on.

02:14 Suddenly, in the first two days after surgery, all cerebellar function is impaired.

02:20 She has problems with coordination, and that's that cerebellar dysmetria and dysdiadochokinesia, as well as problems with language function, she's mute, she is not producing any speech.

02:30 Emotional ability, her emotional coordination is also out of whack.

02:34 So we're seeing problems diffusely across the cerebellum with almost all of the outputs that would come out of the cerebellum.

02:42 So what is the most likely diagnosis? Well, in this case, brainstem stroke is possible after a surgery.

02:52 But the symptoms are not consistent with a specific arterial or vascular territory.

02:57 These are not symptoms on the left side or the right side, on the hemispheres, or perhaps in some of those midline perforators to the vermis.

03:04 This is diffusely involving the cerebellum and doesn't sound like a brainstem stroke.

03:11 What about obstructive hydrocephalus? That could have been developing prior to surgery that presents with prominent headache and nausea, vomiting, papilledema, but we don't see those findings after surgery.

03:21 She doesn't have papilledema and the increased intracranial pressure that was causing headaches and emesis before surgery has resolved.

03:30 What about drug-induced cerebellar dysfunction? That can affect the entire cerebellum.

03:35 She it's unlikely that she's received any of those medications in this situation.

03:40 And so this is unlikely to be the case for this patient.

03:44 This patient suffering from cerebellar mutism.

03:47 This is a very common occurrence in children who undergo a large surgery for a midline cerebellar lesion.

03:53 And we see dysfunction in all cerebellar functions.

03:57 It presents with mutism and that gives it its name, cerebellar mutism.

04:01 But we also see problems in coordinating emotion, and attention and motor function.

04:06 Patients have prominent cerebellar dysmetria and dysdiadochokinesia, as we've seen here.

04:11 And the key is looking for a recent surgical resection or surgical intervention that could have affected the superior cerebellar fibers and cerebellar peduncle.

04:23 So let's talk about cerebellar mutism, and understand how this case drives at the importance of understanding cerebellar circuitry.

04:32 In terms of a definition, cerebellar mutism is a postoperative syndrome characterized by diminished speech output, emotional ability, and ataxia.

04:40 It affects all of those cerebellar functions.

04:44 Patients typically present one to two, or three days after a surgery in the posterior fossa, and often this is a surgery of a midline lesion that extends up into the superior cerebellar peduncle.

04:58 Imaging typically shows normal postoperative changes.

05:01 We don't see hemorrhage or stroke, or some of those important mimics, or differential diagnoses that need to be excluded, as in this case.

05:10 And often the underlying lesion did extend into the superior cerebellar fibers.

05:15 Pathologically, what we think is going on is that this results from disruption of the cerebro-cerebellar circuitry.

05:24 We'll see, in the next few slides, that that system outputs through the superior cerebellar peduncle, and disruption, or interference, or problems with that output circuit results in widespread cerebellar dysfunction.