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A 25 years old woman with a 12 month history of headaches and a 3 month history of "clumsiness walking" is being evaluated. An MRI scan shows that the cerebellar tonsils are in a low position and impinging into the vertebral canal. The patient asks how this condition developed. You explain it is most likely due to:

A. Congenital abnormality
B. Autoimmune disease
C. Genetic disorder
D. Traumatic injury
E. Brain tumor
F. Vascular disorder

The answer is A
This cerebellar description is likely to be Chiari malformation, which is a congenital underdevelopment of the posterior fossa. The underdeveloped fossa then causes the cerebellum to herniate through the foramen magnum. Chiari type I can be asymptomatic in childhood and manifests as headaches and ataxia in the adult. Chiari type II is more severe and symptomatic at birth and is associated with other CNS anomalies such as hydrocephalus and lumbosacral meningomyelocele (spina bifida).

The normal cerebellar tonsils may lie up to 3 mm below the foramen magnum in adults. In general, tonsils lying 5 mm or more below the foramen magnum on neuroimaging are considered to be consistent with a Chiari malformation, though there is no direct correlation between how low the tonsils are lying and clinical severity. With infants, however, tonsils as low as 6 mm below the foramen magnum can still be normal.

Syrinx (syringomyelia)

The term refers to two different syndromes, each representing a different stage of the disease. Wernicke encephalopathy (WE) is an acute syndrome requiring emergent treatment to prevent death and neurologic morbidity. Korsakoff syndrome (KS) refers to a chronic neurologic condition that usually occurs as a consequence of WE.

The classic triad of WE includes:
• Encephalopathy:
The encephalopathy is characterized by profound disorientation, indifference, and inattentiveness. If these are less severe and permit higher cognitive testing, impaired memory and learning are also evident. Some patients exhibit an agitated delirium related to concomitant ethanol withdrawal. An initial presentation with depressed level of consciousness is uncommon, although the course in untreated patients will progress through stupor and coma to death

• Oculomotor dysfunction:
Nystagmus, lateral rectus palsy, and conjugate gaze palsies reflect lesions of the oculomotor, abducens, and vestibular nuclei. Ocular abnormalities usually occur in combination rather than alone.

• Gait ataxia:
Ataxia primarily involves stance and gait and is likely due to a combination of polyneuropathy, cerebellar involvement, and vestibular dysfunction. When severe, walking is impossible. Less affected patients walk with a wide-based gait and slow, short-spaced steps. Gait abnormalities are appreciated only on tandem gait in some patients.

لازم تنتبه لشغلة مهمة هي أنّ الـ triad هذا ما موجود كله غير بأقل من ثلث المرضى. أغلب المرضى يجون بواحد أو ثنين من الأعراض
WE should be considered in the differential diagnosis of all patients presenting with acute delirium or acute ataxia.

كلش مهم تنتبه لإحتمالية وجود الـ WE لأنها underdiagnosed

Korsakoff syndrome (KS) is a late neuropsychiatric manifestation of Wernicke encephalopathy (WE) in which there is a striking disorder of selective anterograde and retrograde amnesia. Although this memory disorder can occur in a variety of conditions that damage the medial temporal lobes, KS is seen most frequently in individuals with alcohol use disorder after an episode of WE, and most patients with KS show typical WE lesions. Any condition that can lead to thiamine loss and WE can also be a cause of KS. 

In some individuals with alcohol use disorder, KS develops without a recognized acute episode of WE, although typical WE lesions may be present at autopsy.

Clinical features:
KS is characterized by marked deficits in anterograde and retrograde memory, apathy, an intact sensorium, and relative preservation of long-term memory and other cognitive skills. Confabulation is a feature in some but not all cases. Attention and social behavior are relatively preserved. Affected subjects are able to carry on a socially appropriate conversation that may seem normal to an unsuspecting spectator. Patients with KS are as a rule unaware of their illness.

atrophy of the mamillary bodies is a relatively specific sign of prior WE, and the finding of small mamillary bodies in a patient with dementia should raise the possibility that alcohol use disorder and malnutrition have contributed to the dementia.

Always suspect WE in alcoholic patients