Neuropsychiatry – 4

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32 Neuropsychiatry – 4

Rudi Kritzinger

	T	F
1. A frontal lesion is the likely cause of dyslexia without agraphia.
2. In receptive aphasia speech can be fluent.
3. Acute confusional states due to carbon monoxide poisoning may last 2–3 weeks.
4. Most patients with CJD have abnormalities on CT brain scan.
5. Normal CSF glucose is 1–4 mmol per litre.
6. Benzodiazepines increase beta waves on the EEG.
7. Primary generalized epilepsy is usually associated with an aura.
8. Absence seizures in combination with generalized tonic-clonic seizures (GTCS) are associated with an increased risk of psychosis.
9. The prefrontal cortex is involved in the control of attention.
10. Autosomal dominant diseases usually show incomplete penetrance.
11. Restriction fragment length polymorphisms (RFLPs) are inherited in a Mendelian fashion.
12. Herpes virus encephalitis is associated with progressive memory loss.
13. Psychosis in HIV is associated with a poor outcome.
14. Huntington’s disease is caused by a CAG repeat of greater than 35.
15. The anterior thalamus is affected in Huntington’s disease.
16. The primacy effect is a feature of declarative memory.
17. Pathological laughing and crying is found in the early stages of multiple sclerosis.
18. Narcolepsy is associated with sudden onset REM sleep.
19. Neglect is a characteristic feature of right-sided parietal lobe lesion.
20. The planum temporale is located close to the auditory cortex.
21. If there is a left-sided hemiplegia, there is increased likelihood of a reading disorder.
22. Serotonin inhibits REM sleep.
23. Obstructive sleep apnoea is more common in ages 40–60 years.
24. Depression may present with similar features to hyperthyroidism.
25. Pantothenic acid deficiency causes dementia.

ANSWERS

1. A frontal lesion is the likely cause of dyslexia without agraphia.

False: Pure alexia (without agraphia) results from lesions to the dominant occipital cortex (Mitchell 2004, p. 89).

2. In receptive aphasia, speech can be fluent.

True: Receptive aphasia (Wernicke’s aphasia, primary sensory aphasia) implies a difficulty in understanding language. The difficulty in comprehension may range from a partial difficulty to a total inability to understand spoken language.

However, the faulty speech is produced fluently and without effort. Normal rhythm, inflexion and articulation are preserved (Lishman 1997, p. 51; Mitchell 2004, p. 72; Yudofsky & Hales 2002, p. 568).

3. Acute confusional states due to carbon monoxide poisoning may last 2–3 weeks.

True: Following carbon monoxide poisoning 20% of patients suffer prolonged delirium lasting several hours to several weeks (Lishman 1997, p. 550; Mitchell 2004, p. 248).

4. Most patients with CJD have abnormalities on CT brain scan.

False: CT brain scans may be normal, even in late stages of CJD and when the dementia is well advanced. CT may show cortical atrophy and ventricular enlargement, but it is usually mild (Lishman 1997, p. 478).

5. Normal CSF glucose is 1– 4 mmol per litre.

False: The CSF glucose is between 40% and 60% of the blood glucose level which should be taken at the same time as the lumbar puncture. 1 mmol/L is abnormally low unless the patient has a very low blood glucose level. Normal values for CSF are:

• Glucose = 2.8–4.2 mmol/L

• Protein = 0.15–0.45 g/L

• Opening pressure = 70–180 mm CSF.

6. Benzodiazepines increase beta waves on the EEG.

True: Benzodiazepines, even in small doses, always generate significant diffuse beta activity. If a particular region does not exhibit the expected benzodiazepine-induced beta activity, that area may be considered dysfunctional (Sadock & Sadock 2005, p. 183).

7. Primary generalized epilepsy is usually associated with an aura.

False: Aura is that part of the seizure which occurs before consciousness is lost and for which memory is retained. Simple partial seizures that become complex or possible secondary generalized are called auras. In primary generalized seizures consciousness is lost at the onset of the seizure and hence these are not associated with aura (Fitzgerald 1996, p. 259; Lishman 1997, p. 249; Sadock & Sadock 2005, p. 379).

8. Absence seizures in combination with generalized tonic-clonic seizures (GTCS) are associated with an increased risk of psychosis.

True: Absence seizures + GTCS in combination carry a 10% risk of psychosis, in contrast with 1% in myoclonic jerks + GTCS and 3% in juvenile myoclonic epilepsy + GTCS (Trimble & Schmitz 2002, p. 42).

9. The prefrontal cortex is involved in the control of attention.

True: Attention is an integrated and multimodal cognitive function. The anatomical substrates include the reticular activating system, prefrontal cortex, posterior parietal regions and temporal lobes (Hodges 1994, p. 2).

10. Autosomal dominant diseases usually show incomplete penetrance.

False: Autosomal dominant diseases are usually transmitted from generation to generation. Incomplete penetrance refers to cases where the phenotype is not transmitted to the next generation. The disease ‘skips’ a generation because despite having the dominant gene the phenotype is not expressed. This may be due to environmental or transmissible modifiers of gene expression. Polydactyly is an example of a condition with incomplete penetrance. Even people with the dominant allele can have a normal number of fingers and toes (Sadock & Sadock 2005, p. 239).

11. Restriction fragment length polymorphisms (RFLPs) are inherited in a Mendelian fashion.

True: DNA can be digested by restriction endonucleases. Endonucleases are bacterial enzymes which cleave DNA at specific sites. Identification of these sites allows a ‘map’ of the genome to be created with the restriction sites being marker points. Random base changes between individuals may alter these cleavage sites. These polymorphisms are called RFLPs. RFLPs are usually inherited in a Mendelian fashion and thus can be used as a marker to track a gene or chromosomal location of interest in a pedigree (Puri & Tyrer 1998, p. 193).

12. Herpes virus encephalitis is associated with progressive memory loss.

True: Although due to rapid destruction of the temporal lobe and thus similarly rapid memory loss, progression can occur. This progression still tends to be faster than memory loss associated with neurodegenerative conditions (Mitchell 2004, p. 201).

13. Psychosis in HIV is associated with a poor outcome.

True: Patients who develop first-onset psychosis after the diagnosis of AIDS have a higher than expected mortality rate (Mitchell 2004, p. 191).

14. Huntington’s disease is caused by a CAG repeat of greater than 35.

True: Huntington’s disease is caused by a CAG trinucleotide repeat expansion in exon 1 of the Huntingtin gene on the short arm of chromosome 4. As CAG encodes for glutamine, the mutation results in a protein with excess glutamine residues. Repeats of more than 35 CAGs are associated with disease. The longer the repeat length beyond 35, the earlier the onset of the disease (Lishman 1997, p. 466; Mitchell 2004, p. 161; Sadock & Sadock 2005, p. 414).

15. The anterior thalamus is affected in Huntington’s disease.

False: Though ultimately almost all areas of the brain are affected in late stage Huntington’s disease (HD), the anterior thalamus is not an area which is characteristically associated with HD. The striatum is the first area to show changes and pathology then spreads laterally to the putamen and globus pallidus (Mitchell 2004, pp. 46, 358; Yudofsky & Hales 2002, p. 926).

16. The primacy effect is a feature of declarative memory.

True: Declarative memory is a form of long-term memory for facts. The primacy effect explains why we can recall the first items from a long list more easily. This is because they have been transferred to the long-term memory. The most recent items from a list are also recalled more easily (recency effect) as these are presumably still in the short-term memory (Gross 2001, p. 249).

17. Pathological laughing and crying is found in the early stages of multiple sclerosis.

False: Pathological laughing and crying occurs in 10% of multiple sclerosis sufferers. It is associated with longer duration and progressive course of the illness, more physical disabilities, greater intellectual impairment and more extensive brain involvement (Feinstein 1999, p. 72).

18. Narcolepsy is associated with sudden onset REM sleep.

True: Narcolepsy is characterized by the tetrad of excessive daytime sleepiness, cataplexy, sleep paralysis and hypnagogic hallucinations. Narcolepsy is an REM sleep intrusion syndrome, possibly resulting from dysfunction in the REM sleep generator gating mechanisms. REM sleep occurs soon after sleep onset, both at night and during daytime naps (Mitchell 2004, p. 224; Yudofsky & Hales 2002, p. 715).

19. Neglect is a characteristic feature of right-sided parietal lobe lesion.

True: In patients with extensive non-dominant (right) hemisphere damage, there is often ‘anosodiaphoria’, i.e. indifference about left-sided weakness. Occasionally there may be ‘anosognosia’, i.e. complete denial that any impairment exists (Lindsay & Bone 2004, p. 111; Mitchell 2004, p. 85).

20. The planum temporale is located close to the auditory cortex.

True: The planum temporale is a part of the superior temporal cortex. It is located close to the primary auditory cortex. It is associated with receptive language functions. It is larger in the left hemisphere than the right. Reversed asymmetry, i.e. larger planum temporale on the right, has been associated with dyslexia (Sadock & Sadock 2005, p. 15).

21. If there is a left-sided hemiplegia, there is increased likelihood of a reading disorder.

False: Reading, writing and language are localized dominant, i.e. left hemisphere, functions in most people. Reading disorders are called dyslexias.

Pure alexia (alexia without agraphia) is associated with left occipital lesions.

In surface dyslexias the patient relies on decoding words letter by letter. Errors are made in reading irregular words where the normal letter sound is replaced by another (e.g. mauve). Surface dyslexias occur in left temporo-parietal strokes and dementias.

Extensive left hemisphere damage results in deep dyslexia where the patient reads by recognizing whole words and their meaning – they are unable to read non-words such as ‘gorth’.

Though dyslexia may also result from neglect (not reading one half of a word) in right parietal lesions, the majority of dyslexias result from left hemispheric lesions. If these lesions were large enough to also include the motor cortex then they would result in contralateral (right) hemiplegia, not left-sided hemiplegia (Hodges 1994, pp. 44, 61).

22. Serotonin inhibits REM sleep.

True: Acetylcholine promotes REM sleep. Serotonergic input from the dorsal raphé nuclei has an inhibitory effect on the cholinergic neurons. Thus, serotonin inhibits REM sleep (Yudofsky & Hales 2002, p. 60).

23. Obstructive sleep apnoea is more common in ages 40–60 years.

True: The prevalence of obstructive sleep apnoea increases during adult life, reaching a peak at around 40–60 years. Thereafter it becomes less common, probably because of the reduction in chest wall muscle activity during sleep which lessens the negative intrapharyngeal pressure (Schneerson 2000, p. 195).

24. Depression may present with similar features to hyperthyroidism.

True: Both hyperthyroidism and depression share symptoms such as anxiety, fatigue, insomnia, lability, dysphoria, poor attention span and weight loss. Moreover, up to a third of hyperthyroid patients would meet the criteria for a diagnosis of major depressive episode (Lishman 1997, p. 508; Sadock & Sadock 2005, p. 2154).

25. Pantothenic acid deficiency causes dementia.

False: Sensory neuropathy is the only neurological or psychiatric disorder that has been attributed to pantothenic acid deficiency (Lishman 1997, p. 571).

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